8 XC Racer Set Up Tricks

Mar 9, 2020
by James Smurthwaite  
We recently listed some tricks and hacks World Cup downhill mechanics use to eke out milliseconds of time on the race track, but what about on the XC side of things? While the downhill mechanics go for precision tuning, for cross country riders, it's much more about weight. Most of the tricks in this list are aimed at jettisoning as much weight as possible so the riders' power is focused on forward momentum. Whether those few grams actually matter is hard to say but if a racer believes they have the fastest bike, it goes a long way in their mind being set on the best result possible. Let's take a look at how they shave those all-important grams.



Custom dropper remotes


With gears, suspension lockouts, and now dropper post remotes all vying for space on XC racers' handlebars, sometimes mechanics have to get creative with controls to help their riders out in the race. This custom Reverb remote belongs to Kate Courtney who has had a remote rewired to fit underneath her grips. Kate has small hands so it means she has to move them less to operate the post and a squeeze of her fingers is all she needs to get her saddle where she wants it. Kate's Scott teammate Andri Frischknecht has taken this one step further. When Mike checked out his bike while filming for Humbled, he noticed that Andri has a button in both grips - one for shifting up, one for shifting down. Both buttons pushed together operate the dropper.



Removing Rotor Bolts

Minus two bolts. Minor gains but many of them.

What does a rotor bolt weigh? Ten grams, maybe. For XC racers, that's ten grams too many and we've seen them taking out a couple of bolts in a pound-pinching bid for milliseconds on the track. While we wouldn't recommend you do this on your own bike, three or four bolts out of six are probably enough to secure a rotor over the course of a 75-minute race.

Removing dust caps on headsets

No dust cap spacer overt he headset bearing in an attempt to keep it real low up the climbs.

Speaking of weight saving, how about dust caps? Some of us probably take them off (or just lose them) on a tyre valve, but some XC racers will take them off their headsets too. One of the perks of being in a pro team is you get plenty of spares so if you do get your headset contaminated you can swap it out from race to race.

Taking the dust cap off also had an added benefit for Manuel Fumic, allowing him to slam his stem even lower than normal so he could get well over the front on the climbs aboard a retro-inspired Cannondale FSi.



Negative rise stems

Steep climbs mean even steeper stems.
Stems and stems. A scary looking Scalpel means business.

Anyone who has been watching the track World Championships in Berlin at the moment will have seen the aero benefits of a low riding position but in XC it's far more about getting your weight over the front wheel to maintain traction on steep climbs. Some riders have specially built stems and others simply mount a riser stem upside down. we've even seen riders mount bars upside down to get a few millimeters lower on the front end.

Enve M5 carbon bars mounted upside down for more low.
Enve bars mounted upside down for more low.



Thumb rests

Cool thumb rests spotted. the idea here is to have some stability while resting your hand on the bars when climbing. Your thumbs come up over the bar and not under like a traditional grip.

On longer climbs, riders like to switch their hand position to give their hands a rest. To give riders another option, TOGS (Thumb Over Grips System) allow them to bring their thumb above the bar, shift their weight, and still retain some control. Think of them as an alternative to bar ends but you can still use all your controls and you don't have to shift between hand positions.



Foam grips


Rather than the rubber lock-ons we see many racers use in downhill or enduro, a good number of cross country riders use foam grips as their main contact point. Like most things on this list, there are weight savings on offer here but for some riders, it's simply a comfort preference as they ride for over an hour each race over rough terrain on bikes that have far less suspension than your average trail bike.



Mud blocking foam

Foam seals the headset.

Any recess in a bike is an area mud can gather and bring with it some extra weight to have to lug around for the next hour of racing. To combat that, mechanics will fit foam in any area the mud can gather to keep it at bay. Yes, it's not pretty but can make a difference if you end up with a race such as Albstadt last year that ended up being sloppier than an explosion in an ice cream factory. The foam also keeps mud out of pivots and critical areas to keep suspension performing at its best.



No sealant in tyres


Sometimes riders will run tubeless setups with very little or no sealant in another effort to save weight. It's a gamble for riders as a single thorn could see you limping round to the tech zone for a wheel change and losing time but if you get lucky, especially on a course where punctures are unlikely, the time savings could be significant.


287 Comments

  • 284 1
 Someone do all 8 to their daily and then report back please
  • 181 1
 I have and KOM'd all the climbs. I'm ready for UCI and Olympics now. From Joe to Pro.
  • 32 1
 Pretty sure I've done the no sealant in the tire one, other than that though...
  • 26 4
 Using less sealant makes sense. It's rotational mass which is the biggest killer. It's a risk but probably worth it for the advantage.
I even do it on my bike only because I'm too lazy to check my sealant and keep it topped up (60ml bottle of Stans in the hip pack sorts the problem)
  • 46 105
flag landscapeben (Mar 9, 2020 at 1:58) (Below Threshold)
 @fartymarty: me too, I ride without sealant all the time, completing dry. I use tubes, they're awesome so much less messy and lighter! And my side walls don't grow mould in the winter Beer
  • 7 1
 Tbf, the togs are something I wad already interested in, there's plenty of times I'll put my thumb over the top of the bars/grip to let my hands rest on a climb or road, but it is sketchy if you hit a pot hole ????
  • 7 3
 @fartymarty: If the course doesn't have thorns or cacti, running sealant is probably optional at the highest levels of XC racing. It won't seal a pinch flat on its own anyway, so why use it?
  • 29 291
flag RoadStain (Mar 9, 2020 at 4:07) (Below Threshold)
 @landscapeben: What is this thing you speak of? "Winter"? Since I moved to FL I have not seen such a thing....plus, with all of the destruction that humans have done (according to a 12 year old Special Needs girl)...I thought winter and snow were all but extinct.
  • 25 41
flag joshdodd (Mar 9, 2020 at 4:29) (Below Threshold)
 Does sealant add to rotational weight? Just a thought. It doesn’t actually rotate with the wheel, it sits in the bottom of the tyre? Or does centrifugal force overcome that and spread it around the inside of the tyre evenly?
  • 132 2
 @RoadStain: reinforcing that “Florida Man” is a thing...
  • 16 0
 @joshdodd: it gets flung out to the outer carcass when moving.
  • 13 0
 @RoadStain: We just have the muddy season and the really muddy season.
  • 4 10
flag MichaelBagby (Mar 9, 2020 at 5:27) (Below Threshold)
 Finally, an actually funny comment
  • 15 14
 @ocnlogan: I pretty sure I don't have sealant. I think it's because I have a tube
  • 7 0
 @RoadStain: According to Jon Snow winter is definitely coming
  • 1 0
 @inked-up-metalhead: nah it’s fine on impacts. I won’t stop using them now that I started.
  • 7 0
 That 3 grams saved made me ride like I did yesterday.
  • 10 0
 @DaFreerider44: You should go tubeless...yesterday my brother got 4 thorns in his tire and it sealed right up. Tubeless is especially good if you're lazy like me and don't want to fix your tubes every other ride Smile
  • 3 2
 @ocnlogan: UST Tires don't need sealant anyway.
  • 14 1
 I have already had my headset come loose, got a flat tire, and fell over the front of the bike and I haven't even left the driveway yet. Good news is the seat was convenient to put down without moving my thumb the extra 6 mm away to push the standard button and I don't have mud coming through my headtube. (;
  • 4 1
 @joshdodd: it does spread around evenly, otherwise it would not be able to close any holes in the tyre
  • 3 2
 @ReformedRoadie: there used to be a game where you could google your bday and man arrested in Florida. Hilarious!
  • 9 1
 @joshdodd: I believe it would be centripetal force in this case and yes, it does spin with the tire. My buddy showed me a demo with a clear “tire” (just a clear tube around a rim) and as it spun, the sealant was evenly distributed once it got going quickly. Diff sealants take more or less rotational speed to get even depending on viscosity. Science!!!!
  • 1 0
 @joshdodd: It spreads evenly while riding.
  • 1 0
 @Acidlegs:
I'd ride that.
  • 2 0
 @JodyLeeJr: the question marks were accidental, pink bike didn't like my phone auto correcting haha into an emoji. I was saying doing it without the togs is kinda sketchy, which is why I want some.
  • 1 0
 @inked-up-metalhead: yes its sketchy.

I have had my hands come off nuts on top tube one foot off the pedal still rolling and trying to save it.
  • 15 5
 @RoadStain: lucky for us you'll be one of the first under water.

Don't move bro stay there in the water and keep telling yourself that its all a left wing conspiracy led by a teenage girl.
  • 1 0
 @fartymarty:

Completely agree. For racing, it could totally be worth the gamble.

I'll just mention that in my case it has not been intentional. I just have gone too long between checking sealant at times...
  • 2 1
 I used to run 3 ti rotor bolts on my DH bike. Still run 3 bolts in all my rotors. Not for weight, I'm just lazy when it comes to installing rotors and after years of running them on a DH bike, I know I can get away with it on my trail bike.
  • 1 0
 @RoadStain: All for the low low price of $10,000!
  • 2 0
 @landscapeben: I recently did tubeless conversion and saved 400gm on a 275 wheelset with 90ml sealant in each wheel. Had similar results on conversions on two other bikes with 26 wheels.
  • 2 0
 @inked-up-metalhead: ive been running togs for awhile now and they are a favourite bit of kit. I ride with my thumbs over the bars all the time, not just sometimes - i feel ham fisted and poor feel with thumb under bar. As long as brake levers set up nice and high as they should be so that heel of hand is pressing into bars on descents, Ive never had an issue with grip or feeling that bars may slip out of hand.
  • 2 0
 @reverend27: you forgot to tell him to take deep breaths as the water gets higher
  • 1 0
 @reverend27: I've had it where one hand went forwards, the other still on the bar, so it was kinda a half superman plank while trying not to crush my nuts or ride into traffic. 10/10 would not recommend.
  • 2 0
 @inked-up-metalhead: I've used Togs for quite a while now and like them. I mainly use them when climbing. Not sketchy at all even on techy climbs. I really like how I can use them as leverage on steep climbs. They are even hinged so they go on without removing the grips.
  • 1 0
 @vjunior21: This had me rolling. Lol.
  • 1 0
 @fartymarty: Her mother was a mudder!!
  • 1 0
 @Ritgut: Must have switched from DH tubes? Standard tubes are only ~200g each.
  • 1 0
 @Maestroman87: I think he meant total for two wheels.
  • 1 0
 @fabwizard: Yup, that's how I read it. 400 grams saved is the weight of the tubes. Add valves and sealant and I cant see a 400g savings unless he was switching from heavier DH tubes. I am inquisitive because I switched to tubeless and didnt really save any weight at all... but I was using 120-140mL of sealant.
  • 89 0
 How about removing the fork protector on the lefty? Prob more weight saved than a rotor bolt
  • 335 9
 They already removed one fork leg, give them a break
  • 20 3
 I heard the rotor bolt is to change rotors faster, not for weight saving.
  • 19 0
 @WAKIdesigns: Hey Waki, did you just moved to Fiji from Sweden?
  • 35 9
 @brcz: Yes. Mentally. I identify as a Fiji:an.
  • 4 0
 @Loris123: Drillium your Centrelocks if you ride Shimano
  • 2 2
 @WAKIdesigns: I do that at least 3times a week!
  • 2 2
 @Loris123: I think you are right, otherwise they would be using 6 Ti rotor bolts. 4 standard bolts = 18 gr. 6 Ti bolts = 12 gr.
  • 1 1
 @PinkyScar: SRAM makes centerlocks too. CenterLine X Rotor
  • 8 1
 @MikeAzBS: 3 ti bolts = 6g
  • 11 0
 @Loris123: Why would they change a rotor out during an XC race?
  • 1 0
 @Loris123: correct
  • 8 0
 @tacklingdummy: Totally. You have spare wheels, you don't stand there getting yer torx out looking for the rotors you brought.
  • 4 1
 @Loris123:

Whoever you heard that from doesn’t watch XC racing, they change out entire wheels not rotors. It’s way faster to remove an axle and slap a new wheel in than it is to remove the wheel, change the rotor and put the wheel back in.
  • 4 2
 @Maverick18T: But now the spare wheels have a knackered rotor. Toss a new rotor on before your rider makes it back 'round! Yes they'll swap wheels but fix it to maintain spares.
  • 3 3
 @AverageAdventurer:
Wheel swaps are almost never because a rotor went bad. Regardless even if that was the reason having 3 or 4 bolts instead of 6 would save you something like 10 seconds tops, as you should be using a drill motor to do that work quick.
  • 4 0
 @MikeAzBS: why use 6 ti bolts when you could use 4?
  • 2 2
 @tacklingdummy: they wouldn’t change it, but if they were far away from a technical assistance zone they could take off a bent rotor. Saves having to run up to 6 km.
  • 1 0
 @KiwiXC: I've had the same thought when considering 6-bolt vs centerlock, but more in the context of backcountry rides or touring rather than xc-racing. I still prefer 6-bolt, but in the event of a bent rotor, you can remove the caliper and zip-tie it to the fork lowers or handlebar, so it's not really an issue.
  • 47 7
 I’m thinking, “why not take a shot of espresso and loosen the pipes up a bit?” Seems like dropping a load would drop more than 30 grams per wheel ????. But on a more serious note, Nico Vouilloz used to run 3 bolts per wheel on DH races—proving XC racers aren’t the only weight weenies out there.
  • 24 6
 Swedish Tobacco “Snus” is much better at pushing the load. I am surprised it is not the part of their pre race protocol.
  • 7 7
 I'd be tempted to add more weight for DH, get gravity to help me a bit Smile
  • 32 6
 @Jacquers: uhh that's not how gravity works
  • 6 2
 @WAKIdesigns: that's part of every alpine ski racer protocol, from local fis races to world cups
  • 12 6
 @crashtor: I'd be interested to see some science behind these positions. I've been on several rides where mates who are heavier than me and out of shape have greater speed and momentum going downhill than I do and I struggle to keep up with them. Then things are reversed on the climb. Modern downhill requires more athleticism than it used to do, being lighter fitter and stronger are benefits, but if you straight roll down a slope it seems to me that there is an advantage to more weight.
  • 23 4
 @landscapeben: Maybe they're just faster because of their massive, heavy balls
  • 3 3
 @landscapeben: when skill is equal it would be interesting to see the impact of weight in gravity racing. I’ve spent a bit of time at karting tracks and bigger drivers who know how to corner can hold a lot of momentum and win races when you’d think the power:weight would hold them back.
  • 20 11
 @landscapeben: Take two balls, same dimensions and different weight. Find a reasonably high place and let them go at the same time and see which one lands first. Let me know. It's called gravity

What you are experiencing on the downhills is a different amount of momentum, which is a result of the speed AND the mass of an object. It means that even if you're going at the same speed as your heavier friends the same impact (for example hitting a root) is going to slow you down a little bit more than them. And that applies to basically anything, from car accidents to orogeny.


Spoiler: the balls land at the exact same time
  • 8 0
 Or you could remove rotor bolts AND have some coffee
  • 4 11
flag RoadStain (Mar 9, 2020 at 4:10) (Below Threshold)
 Some years ago I was part of a study (at IronMan) where there was some grad student trying to figure out the physiology and human process of "big potty" before a big event. Seemed that with or with out coffee, somehow the body knows "hey, it is time to go" about 45 minutes or so before we got into the water....crazy how intuitive the human body is, even when we do not know it is being intuitive.
  • 9 5
 @crashtor: yeah, it's all interesting but the reality is that pros run relatively heavy bikes because they focus on something that works rather than what seems hypothetically feasible. It is not that hard to build a sub 14kg DH bike, but you are highly unlikely to find a bike lighter than 15kg on WC circuit.

Their bikes need to survive a week of practice with minor swaps (so that they lose as little practice time as possible, don't spend the day to carry the bike down the hill) - this is not the reality of an overcashed wanker who can't ride so instead of learning to, he finds it as a point of honor to build a sub 13.5kg Dh bike.

Back to momentum, the steeper the track the less it matters. Unlike XC, the acceleration is in abundance, 1kg out of total 85kg+ rider+bike will not make any bigger difference. What folks do on World Champs has more to do with superstition than practicality. Pros say it themselves.
  • 14 1
 Have you considered the possibility of taking a dump pre-race AND getting your mechanic to lighten your bike?
  • 17 4
 @landscapeben: Increasing the weight will make you slightly faster downhill, especially at high speeds, as the gravitational force accelerating you increase more than the aerodynamic drag. That is if you do not pedal. This is due to gravity being roughly proportional to your size cubed while drag is roughly proportional to your size squared.
However assuming the gained weight is non-productive (fat for example) you will be slower under powered accelerations (pedaling), roughly proportional to the weight gained as a fraction of total system mass (including bike and kit)
All this though is assuming you are riding a smooth surface, which you most likely is not. There are pros and cons to to being heavy over bumps, but being heavier here will most likely be an advantage since the suspension will work better when the undamped mass is a smaller fraction of total mass.
So from a mechanical perspective you'll most likely be better off being heavier when going downhill if there is little to no powered accelerations or the extra mass is productive (muscle and circulatory system), however carrying extra mass will put an added strain on the rider. Try imagine landing a huge drop with a heavy backpack. The extra work done by carrying the additional weight will also make the rider fatigue more which will also be a factor if significant rider input is needed.
  • 4 1
 @crashtor: Two different balls won't land at the exact same time wherever you do the experiment on earth, that's why Galileo had to think about two balls linked with a string to prove his point.

@landscapeben I don't know if someone published some datas about mountain bikes, but there is many thing about the subject. there is weight limits in some winter sports for this reason.
there is two things you need to know
"where does the energy come from"
and
"where does the energy goes" (or more often "what part of the world is hotter now)
And then do the maths. kinetic energy, aerodynamic losses, tires losses, kinetic energy lost on roots,...
On a rough track, #1 loss of kinetic energy is from impacts with "square bumps" Rider weight does have some effect on it, but suspensions settings (including tire ans tire pressure in it) is the first thing to look at.
When climbing, your weight add up to the potential energy, and energy only comes from the rider input. But track isn't super smooth so there is still plenty of energy lost to the ground.
  • 5 4
 @faul: nothing to yyou, general comment about paralysis by analysis. - one can just watch World Cup race and see that people of different physique on different bicycles come in very close time intervals to each other, and order tend to change depending on the race. If anything, pondering whether a ball of Iron falls down faster or slower than equally sized ball made of aluminium alloy and how does it affect riding a bike down the hill greatly reduces your chance to improve your descending times as well as being even slightly succesful at other thigns like finding a female willing to shag you. Even in physics, nobody wastes time wondering whether heavier DH bike is potentially faster or slower than a lighter one. The human skill and fitness factor, as well as ability to setup the bicycle are grossly predominant. Just saying... Smile
  • 1 2
 @crashtor: "It means that even if you're going at the same speed as your heavier friends the same impact (for example hitting a root) is going to slow you down a little bit more than them."

I see what you are saying but there is more to it than that I think. Perhaps greater rolling weight builds momentum faster overcoming friction more easily? I've seen the same thing happen with mates on smooth tarmac, they just seem to accelerate faster with less effort initially.
  • 2 2
 @Sylesej: Thank you this is a sound answer that makes good sense! Beer
  • 3 2
 @WAKIdesigns:
If you want to put the odds in your favour, you may want to understand what do what. Rider's skill is a huge factor, but it's not the only huge factor in the equation. You can't go faster than your brakes (or tires, or bike fit, or...) allow, no matter how much you're skilled.
If you want to adjust your time on track or predict who will win, Physics knows but doesn't help: there is a chaotic system so the best model you can run is "luck". There is still some trends you can guess but it stops here.
  • 2 1
 @meagerdude Just taking a dump is so amateur. XC racers already calculate ahead to not have a heavy load in the UPPER digestive system less than 3 hours before a race.
  • 1 0
 @WAKIdesigns: but what about a ball of commercially pure aluminum vs a ball of aluminum alloy?
  • 1 0
 Vouilloz was probably thinking about braking and changing direction rather than straight line speed
  • 2 1
 @RoadStain: my body is the exact opposite of this. Without without coffee, 45 minutes after I've started whatever activity I'm doing is more like it...
  • 4 0
 @Jacquers: the lighter the bike is, the quicker you can get back up to speed pedaling out of the corners.
  • 2 1
 Race day breakfast: Prune Juice, Raisin Bran, and Espresso.
  • 2 1
 @j-t-g: And some Ex Lax chocolate for dessert.
  • 3 0
 @meagerdude: the lighter the bike is. the less momentum it carries through rock gardens and flatter sections....its all a balance.
  • 1 1
 @crashtor: hey semantic Galileo, chill dude.
  • 1 1
 @crashtor: hey semantic Galileo, chill dude
  • 1 4
 @faul: you do realize that Amaury’s bike is almost a full kg heavier than Loics?
  • 3 1
 @alexhyland: I hit the window somewhere between "once I get all my gear on" and "a point just inconvenient enough from the trailhead to not turn around".
  • 3 0
 @Connerv6: yep. Always pack tissues haha
  • 3 1
 @WAKIdesigns: I don't know. And how does this fact prove me wrong?
  • 6 4
 @crashtor: uh, no they don't land at the same time. What you describe only works in a vacuum. Air resistance my friend.
  • 1 5
flag WAKIdesigns (Mar 9, 2020 at 10:43) (Below Threshold)
 @faul: it depends on the perspective. From Perspective of a racer it doesn’t matter at all. From perspective of a bloke who requires to have minimum knowledge from a particular discipline in order to get faster on a bike - it doesn’t matter. From perspective of a world cup mechanic it makes very little sense. From Perspective of an engineer improving particular part of the bike it makes some sense. From perspective of a hobbyist interested in a particular subject it makes unlimited sense. In general Skill will override such details. Every songle time.
  • 4 0
 Perhaps a valid comment for us Joe Schmoes with dad bods but I think it’s safe to say that a WC XC racer whose full time job is going fast on a bike has figured out down to the second when to take the pre-race dump.
  • 4 2
 @pinkbiker3000: That's why he said "same dimensions".
  • 6 1
 @Dethphist:
He said same dimensions but different weight. So given the same aero drag the heavier one lands first, when experiment is conducted in air. In a vacuum they land at the same time.
  • 1 0
 It's probably not a weight weenie thing, it's probably more that the team mechanics get tired of removing the rotor bolts over and over when they service the bikes.
  • 3 4
 @landscapeben: Freefall=Vo-(9.8m/s)(time)
The force vector on an inclined plane is f=mass*9.8m/s^2*sin(angle of slope)
So yes, if friction and drag are ignored a heavier rider will accelerate faster.
  • 5 2
 @clink83: look at your equation. F=maSin(x) where x is the angle of the plane. I don’t care how much more something weighs, the acceleration in that direction is still 9.8sin(x). Your reasoning is circular reasoning. More mass -> more force ; therefore, more acceleration? No, more like more force because of more mass, but same acceleration.
  • 2 1
 @clink83: also look at your equation regarding free fall, do you see mass anywhere in it? That should be your first clue that your conclusion that heavier items accelerate quicker is incorrect.
  • 1 4
 Holy shit... Pinkbike is transforming...
  • 3 2
 @Austink: you have a complete and fundamental misunderstanding of physics. T
There is no circular reasoning.
www.studyphysics.ca/newnotes/20/unit01_kinematicsdynamics/chp06_vectors/lesson25.htm
  • 3 1
 Uh, force of gravity is m*g. Not m^3*g. You have it wrong, at higher speeds drag increases far MORE than other forces in play. Which is why aerodynamics only matter when you go fast. More importantly, as others have pointed out, acceleration due to gravity doesn’t even depend on mass at all. As others have also pointed out, momentum does increase with mass, so heavier riders can bash into things and slow down less. @Sylesej:
  • 2 0
 @clink83: dude, you’re so wrong. The F in F = m*g is the force accelerating the object in a gravitational field, which does scale with mass (obviously), but the acceleration does not change. Doesn’t matter if you’re on a slope. The little video you posted is hilarious; two objects with different surface areas touching the slope means they’ll have very different friction.
The fundamental fact that acceleration due to gravity is mass independent, and only depends on friction forces (air drag, rolling drag, etc) is so basic that it’s famous. You are quick to call people out on not knowing physics for knowing it so poorly yourself.

There’s a whole section in this wiki explaining why, it’s pretty simple once you see it written:
simple.m.wikipedia.org/wiki/Acceleration_due_to_gravity
  • 4 0
 To be clear, heavier bikes/riders will accelerate downhill faster. It is because for bikes, and to a slightly lesser extent humans, drag forces (aerodynamic, rolling, bearing drag, all of the drag forces added together) don’t scale exactly with mass. So the force due to gravity increases but the counteracting forces of drag don’t increase as much. You could call this “friction density” although I’m sure there is an appropriate term for it that I don’t know.

So, F = Fg + Fd
also F = m * a, or a = F/m
Fg = m * a, so Fg scales linearly with mass
Fd doesn’t scale linearly with mass, and in this example we’ll say it doesn’t change at all between two identical bikes (4N for simplicity, in reality it would be some function of surface area, frontal area, tire pressure and contact patch, bearing friction, speed, wind...) one with a lead-filled down tube (12 kg vs 10 kg without the lead)
F for the normal bike = (10 kg * 9.8 m/s^2) + (-4 N) = 94 N
And the acceleration is then 94 N/ 10 kg = 9.40 m/s^2
F for the lead-laden bike = (12 kg * 9.8 m/s^2) + (-4 N) = 113.6 N
And the acceleration is then 113.6 N / 12 kg = 9.47 m/s^2
  • 2 0
 @dmclemens: thank you. It seriously makes my blood boil seeing people argue that mass affects gravitational acceleration and act like they can back this up with some equation they clearly misunderstood in high school.

@clink83: I literally have a masters degree in physics and taught university labs in physics (including Newtonian mechanics)........ feel free to educate me with your expertise!
  • 2 0
 ..
  • 1 0
 @Austink: what's the actual answer to this riddle then in layman's terms. Why does my chunky mate out accelerate me on a smooth slope downhill without pedaling?
  • 2 0
 @clink83: that video is completely laughable. The reason two things go down the slope at different speeds is due to their frictional force interacting normal to the plane. His wet paper towel in no way eliminates friction, and that “experiment” wouldn’t even be fit for an elementary school science fair.
  • 5 0
 @landscapeben: the one word answer is inertia. An object in motion wants to maintain that straight line motion unless acted upon by outside forces. Your heavier friend carries more inertia than you; therefore, he is bound to maintain that inertia and be comparatively less affected by the stuff slowing you down (bumps etc). He isn’t accelerating any faster due to his mass(weight), you are just being slowed more because the external forces proportionally affect the body with less inertia more.

You and your small dog are both running at 15km/h (note you are not accelerating at all in that direction) and there is a small fence in front of you. The dog will probably run into the fence and come to complete stop, the fence provided enough force to completely bring that moving body to rest. You on the other hand will probably plow right through that fence given your larger inertia wasn’t as affected by the small force of the fence.

When riding downhill there are many things acting upon you that are related to ones mass, but gravitational acceleration is not one of them. This is why the gravitational constant for earth’s gravitational pull (g) is a constant value and can be used to calculate all sorts of stuff independent of the mass it is acting on.
  • 1 0
 @landscapeben: I should add that it isn’t really a simple problem to apply basic physics to. Newtonian physics gets messy when trying to apply it to real world scenarios as there are many outside forces to keep track of. @dmclemens did a good job trying to pick apart some of the stuff in play.
  • 3 0
 @Austink: I appreciate you explaining it simply like this, as I have an inquisitive, but not very academic mind Beer
  • 2 1
 @Austink: although you are right, but.. In common conversation, the word acceleration is understood in a broader meaning, which already includes all the interacting forces and is a visible net result of them all, instead of just g=9.8. And as for a teacher, it is good to be midful of that distinction between a physical term and a conversational term. Well, maybe by the 1st year of uni students should already know that distinction themselves, but there may be some who don't.
  • 2 1
 @Austink:
www.math.utah.edu/~eyre/rsbfaq/physics.html
Tell me how the relevant equations in the "why heavier skiers accelerate faster" section is wrong then. note the A = g*sin(theta) - mu*g*cos(theta) - (Cd*Ap*rho*V^2)/(2*m)
  • 2 1
 @clink83: go read your older post: “if friction and drag are ignored a heavier rider will accelerate faster.”

Why are you posting an equation and link that has both kinetic friction and drag? As already discussed mass does affect both drag and friction, but when you eliminate those (as you stated) you are left with gSin(x), something mass independent. I already know those things affect sliding bodies in the real world, but that is not at all what you said earlier. Posting random equations you find on google is only further showing your lack of knowledge on the subject. FWIW a bike doesn’t even have that same kinetic frictional force because when a tire is rolling along the coefficient of static friction is high enough to prevent most sliding(this is why we like sticky tires).
  • 3 0
 @GZMS: I understand what you are saying and yes many people would have a different connotation of what acceleration actually means. The big take away is that the acceleration all bodies feel due to earth’s gravitational pull is independent of the objects mass. Where people may get tripped up is that doesn’t mean all objects in the real world will go downhill the same speed. But this is due to retarding forces interacting on the body, not it undergoing more gravitational acceleration due to mass.

This misconception largely is due to how people perceive motion in their reference frame. If a heavier rider is pulling away it looks like he is accelerating away from us. But from a 3rd party view (Who also has a reference for how quickly an uninterrupted body should go) I see the bigger rider going closer to the speed he should and the smaller rider actually slowing down. The smaller rider still has the same gravitational acceleration working on him, but he also has retarding forces that are working opposite of him in a manner that proportionally affects him more.

In a bike rolling along a smooth road (with similar tires, frontal area etc) the big one in play is just air drag.
  • 1 0
 @crashtor:

That would be accurate if you lived in a vacuum.
  • 3 0
 @clink83: that paper describes exactly what I described in my post w/ equations. They use a water bottle, I used two bikes with different masses. You are wrong that heavier things accelerate faster in gravity. They have more mass per drag though, and so do accelerate faster (as I explicitly state). Fact remains that you called people out on their physics knowledge while clearly not knowing what you’re taking about at all.
  • 2 0
 @landscapeben: See my above post. It's because as mass increases, drag increases less quickly, so heavier bikers/bikes have a larger mass per drag ration. Since the total force is the sum of gravity and drag, increasing mass without increasing drag results in more total force and therefore more acceleration.
  • 2 0
 @clink83: You have a knack for finding shitty examples, I'll give you that. This "paper" does exactly what I calculated for you in the equations above: if you increase mass and not drag, you'll accelerate down a hill faster. It's just not because of the reasons you said, and the reasons you put forth demonstrate a total lack of physics understanding, which is what you were accusing others of. So...go find yourself a crabby patty I guess.
  • 2 1
 @dmclemens: he is really good at finding examples that completely disprove what he is proclaiming.....
  • 1 2
 @Austink: this is not the only area he acts like this... try to talk to him about dropper posts in xc racing or how top racers train... he even argued for benefits of aluminium woo woo bricks reducing vibrations and most arguments end with something like “Pinkbikers know sht about XC athleticism, they just use lifts”.

It was a great read on physics but in reality of riding a bike down the hill depending on countless variables, riders and bikes mass matters very little. Skill and Bike setup override all of this, even fitness to a great degree. None of us, given on world’s best bike amd engineer support Stands any chance against overweight Or undernourished Sam Hill on 2010 Sunday...
  • 1 0
 Pretty sure Vouilloz only had brakes because he got sponsor money. Because I’m not sure he ever used them.
  • 1 0
 @gkeele: maybe even 3 balls
  • 28 0
 If one of your rotor bolts weighs 10 grams, you should swap the ones you have that are made out of depleted uranium or tungsten out for something lighter like steel. That way you could save almost 50g per wheel.
  • 3 0
 At 10g per bolt even I would be swamping them for Ti bolts. This coming from someone who wraps old innertubes on both chainstays and has steel braided hydraulic brake hoses.
  • 6 0
 Yup! Out of curiosity I weighed a couple of my plain old steel XT rotor bolts. 3 grams each. Figure Ti bolts probably weigh half that.
  • 7 0
 I feel weighing a rotor bolt for this article would not have been a hardship...
  • 16 0
 Another reason for this is probably world cup mechanics pride in their work. If your sole job is working on one or 2 bikes, and you are obviously at the top of your game, then trying to find ways to make the bike lighter would be a fun part of the trade.
  • 18 3
 @RoadStain: "12 year old Special Needs girl" Really? I mean REALLY?????? Just cos you don't agree with someone doesn't mean you have to be tw*t. Way to go big man.
  • 18 0
 In the US we have this subset of humans called "Florida Man". You should google it. They're everywhere and even PB won't be immune to them.
  • 8 0
 I remember we went through this gram saving phase in BMX in the early nineties when guys were drilling holes in their cranks to make them lighter and holes in their plastic saddles. It might not make any measurable difference but psychologically if it makes you feel faster then it's a positive thing. As long as the bike is safe to ride, shave away. Guys even striped all the paint off their frames to save weight. Whatever floats your boat.
  • 5 0
 Did the same some 20 years ago but in the prototype 3/4 tonne racing sailboat. Already built up to be light and completely empty from the inside. So we entered with some angle grinders, drills, gas masks and vacuum cleaner and exit 2 months later with 65 kilos of extra weight.
  • 1 0
 Individual changes don't matter, but the sum of small changes does. They have applied this philosophy to lighweight cars like miata to shave hundreds of lbs.
  • 7 0
 All pretty interesting stuff. Its relatively obvious in hindsight when your goals are aero, and weight savings, but still an interesting read.

I also feel pretty safe saying I will not be implementing any of these on my all-trailduro bike. Particularly the "4 bolt" rotors, yikes!
  • 1 0
 I feel like all the XC bikes should be homonlongated to a minimum weight. After all, racing exists to sell bikes, and none of us really care in making a bike perform well for one race only.
  • 8 0
 I bet they're all still running star nuts in forks and top caps. Given these are only required to hold it tight before you pinch up the stem these can also be removed.
  • 2 0
 I also would have thought star nuts and top caps would be optional, though I’ve seen enough World Cup racers knocking their bars back into alignment after a crash that I wonder if that sort of crash would also loosen the headset if there wasn’t a top cap
  • 1 0
 @something979: star nut isn't strong enough to hold your stem back or to put everything back in place if it moves when tightened. The nut will move or be destroyed with less effort than that.
  • 10 6
 The low front is not for more traction, but for more tension in the back and therefore a better power transfer from the arms to the legs. If you have not tension in the back, this is the weak link where you get pain if you put the hammer down. If you get backpain because of the low front, you have to little strength in your core.
  • 3 2
 Every time I see those negative rise stems on those XC bikes I wonder how long it takes before they finally develop a direct mount stem. So a stem that attaches directly to the (lower) fork crown. It much easier to set the bars straight and it is probably lighter too. I've been saying this for at least three or four years now so it should be any time now that a brand comes up with it and calls it innovative. Or someone calls me out explaining why it would be such a horrible idea. Obviously you're still going to need some kind a "dummy stem" to keep the fork in place but that's pretty much it.
  • 1 0
 @vinay: Sell, maybe some drop bar...
  • 1 0
 @vinay: A direct mount isn't low enough
  • 1 0
 I thought it was to better recruit the glute muscles.
  • 2 2
 Uh no. They have low stems to make the bike fit them, which keeps the front end low on climbs. 29ers have long forks and tall head tubes. If you ignore the stem and look at the saddle to bar drop they are about the same as a road bike.
  • 2 0
 @clink83: right and to me it really seems like it's only the shorter riders who have the extremely negative rise stems. The taller guys are all riding a much more normal stem setup.
  • 1 0
 @Thisisbenji90: yea on the bigger bikes the issue is often the head tubes are too short, so you end up with a pile of spacers under the stem with a normal position. I wish they would put more thought into the S and XL frame geometry.
  • 1 0
 I thought it was because Trek didn’t have a 27.5 and the 29ers a few years ago were too big for Anton Cooper.
  • 1 0
 Looks like both of those neg stems are Antons . @KiwiXC:
  • 7 1
 I will be removing my left crank later today to save some weight! I’ll report back later with results. Switching to light weight Spd crocs as well.
  • 4 0
 As long as you don’t have a left side only power meter you should be ok!!
  • 4 0
 Reducing the weight of bikes is fun and often provides a notable feel difference, but the key is choosing parts and still having 100% functionality and physical safety.

I'm certain these XC race rigs are perfect for their application considering how often they are looked after and the parts are replaced.
  • 4 0
 Had a friend who was running three rotor bolts and it failed by shearing all three mounts off the hub. So even if the three bolts might secure a rotor and take braking force, the hub itself might require all six. (This was mid 2000s american classic rear hub)
  • 2 0
 But, there were some crankbrothers and mavic hubs that could brake with all the 6 bolts in place, in the same era!
  • 3 0
 Surprised by anyone leaving out sealant... seems like the benefit of being able to avoid losing big time would far outweigh whatever small time loss the little extra weight could save, especially with the relative fragility of XC tires.
  • 5 0
 I can’t remember the last time I watched a World Cup XC race and watched anyone getting a bent rotor replaced.
  • 2 0
 I can't speak for XC, but in cross, sometimes a rotor starts rubbing, might not actually be bent. Racer comes through the pit and gets a wheel, so you wouldn't actually see anything with the rotor which is dealt with after the fact. I'm guessing it's the same in XC; a racer hears a rotor start to rub, hits the pit for a new wheel and is off again.
  • 2 0
 @pbayne29: But if the rotor isn’t bent and the brake starts rubbing, the rotor isn’t the issue, it’s the brake. Unless the rotor is loose maybe
  • 4 0
 Coming soon...the split head tube! Get those bars even lower by mounting them between the top tube and the downtube! Just don't tell them it'll weigh a bit more...
  • 4 1
 Yeah I worked in a bike shop for a few months and there was this weird weight weenie roadie dude, who punched out his star nut after attaching the stem, because of weight reduction. He also was of the thiccer kind so...
  • 20 0
 Punching out the star nut, that's gotta be some kind of euphemism.
  • 4 0
 If he had a lightweight road bike, it most likely had a carbon steerer, in which case he should have been using an expanding wedge, not a star nut. So, not quite as extreme as re-installing and then punching out a star nut every time you adjust your headset, but it's still some weird weight-weenie-ism.
  • 3 0
 Note: placement of those remaining three bolts may or may not be important. Best to try all possible configurations down a really steep slope.
  • 1 2
 It's just wheel balancing bro... Even at that kind of moment arm every gram counts!
  • 9 7
 4 bolts on rotors are not for weight saving but for the ease of changing a rotor wether it's bent. Bikes are checked over twice a day so for the sake of safety 4 is still enough.
  • 28 1
 If only Shimano could come with a "one bolt" solution to this... Oh wait!
  • 2 2
 @faul: Not every team has hubs with centerlock due to their sponsors, so that's how they get around it. Only privateers have the luxury of choosing everything they use
  • 43 0
 @SanitariuszMariusz: privateers have the luxury of being able to choose their parts. Now that is looking on the brightside
  • 12 0
 Doesn't make sense to me, the pro's would just change the wheel surely
  • 2 0
 Very good observation there which means it probably is for the weight saving @xrob:
  • 1 4
 @enduroNZ: if the wheels are that easily replaced on a pro team, they could probably get away with just roughing the surfaces and putting on a slip of epoxy. Glues can be engineered to such extremes these days.
  • 3 0
 When have you ever watched an XC pit crew change a rotor in a pit stop? They just change the entire wheel?
  • 1 0
 I use 3 ti bolts + 3 Trickstuff alu bolts per wheel for a few years on my XC bike without any problems.
I weight 70kg.
  • 5 1
 youtu.be/lsJuCHb5Rh4?t=161 This is a Cannondale mechanic explaining exactly this topic
  • 1 0
 I would argue DH is far more rough on rotors and changes them with much greater frequency. The 'faster rotor change' is BS is my humble opinion. As someone said earlier, the steel XT rotor bolts are like 3-4 grams. Most of the XC weight savings tricks are legit. The rotor bolt thing is bullshit honestly.
  • 1 1
 @lifeofloon: they rebuild the bikes constantly, and if you are travelling from race to race you aren't going to want to travel with the rotors attached.
  • 1 0
 @clink83: so it's laziness?
  • 5 0
 handlebars upside down, okay lets draw the fucking line somewhere.
  • 4 0
 Rotor bolt weight 10 grams? In my scale a stell rotor bolt weight 2 grams and I think a titanium one weight even less.
  • 3 1
 I've seen on Greg Minnaar's bike, they took out the rubber ring that seals the freehub to the hub body reducing drag for pedaling. Kinda like the headset top cap but much more effective. Kinda sketchy if you ask me though.
  • 1 0
 Removing the freehub body seal reduces drag while coasting. That’s more important in DH anyway.
  • 3 0
 That button for the dropper post is just a ruse to hide that she is actually riding an ebike!!! Quick grab the thermal imaging camera!
  • 4 0
 What on earth are those stems?
  • 9 0
 The consequence of 29" wheels and very short people.
  • 1 0
 The stems we've seen but upside down bars to get even lower is a new one on me.
  • 2 0
 @trails801:
There are actually some bars that are designed as + or - 5mm rise.

Like these: us.ritcheylogic.com/us_en/superlogic-flat-5-handlebar
  • 2 0
 Marin Bullfrog Trail 1994 or 5. Did most of this and one more. Primax E headset with the locknut cut off and just loctite. It survived the frame.
  • 2 0
 How about other "tricks" like 40T chain rings, cutting knobs for better rolling resistance, custom dropper posts, drilled saddles,...
  • 1 0
 Can't wait the the e-mtb version of this for their XC tips and tricks.

I have both a e-mtb (strictly for adventure and social rides) as well as an Enduro bike so I do get to add my piece to the e-mtb comment side. : - )
  • 3 2
 The lefties still exists? OMG, does the weight weenies think it's that much more beneficial to have one thick stanchion weighted on that one side? Is that to compensate for the small weenie on the right side?
  • 2 0
 i assume a lot of these things are done just for fun?
else, they'd shave their head for weight savings and stuff like that. wait, i gotta check some pics real fast...
  • 2 0
 if a pro xc racer say my xc race bike they would want to die or kill me 1. quad piston brakes 2. DH bars 3. no attempt at weight savings at all 4. flat pedals
  • 1 0
 What about removing the steerer compression bolt? Once yer pinch bolts are secured, the top cap doesn't even need to be there.. Weight weenies in the bmx world have been doing it for years. I'm surprised not to see it here.
  • 11 8
 XC Stems make me wanna puke.
  • 29 1
 Then better not eat them!
  • 4 1
 Dammit.....no wonder i cant get any KOM's
  • 3 0
 Togs on all my bikes. I love them.
  • 4 5
 How many times is somebody gonna post that the removed bolt is to speed up rotor changes, not for weight, which doesn't matter as much near the hub anyway. Those rotor changes are not during a race but during the days/week leading in. A team of three riders with 3 wheel sets per bike has lots of rotors. If a change is called for, like floating vs. solid, ice vs. non-ice, or a more solid pattern, it can speed up the change of 18 rotors. The rotors all need to match on race day so that the pit swaps are just for wheels. Also bent or otherwise damaged rotors during practice can be swapped faster. On the off chance that a mechanic has to change rotors on a backup wheel set during the race, it does speed that up too, although sometimes for race day, all the bolts are actually put in.
  • 4 0
 But if they are using proper tools, having all the bolts will slow down a rotor change by something like 10 seconds a wheel. Doesn't really seem worth the trouble of possibly fouling the threads in the hub with dirt.
  • 2 0
 Didn’t realize I was majoring in science by the time I got through the comment section...
  • 2 0
 What does a rotor bolt weigh? 2.095g including slightly used blue threadlocker it seems
  • 4 1
 The stem on the Cannondale, in few picures, is Leonardi.
  • 1 1
 @landscapeben:
Freefall=No-(9.8m/s)(time)
The force vector on an inclined plane is f=mass*9.8m/s^2*sin(angle of slope)
So yes, if friction and drag are ignored a heavier rider will accelerate faster.
  • 1 1
 I'm surprised there aren't XC race specific rotors and hubs with just 3 bolts. If all XC racers run 3 bolts only there's an indication of demand. Heck, OEMs can make the 3 bolt versions and probably sell it for MORE $$.
  • 3 1
 So does your top cap actually do anything to hold the stem on the steerer tube or is it just the clamping force of the stem?
  • 2 0
 If gives you the initial bearing preload to make sure the headset is free of play prior to tightening the stem. But once you torque the stem bolts, they take over that job and the top cap is no longer needed.
  • 1 0
 Been racing XC for 17 years and never used any of these weight saving tactics. In other unrelated news I've never won a big race, but I'm sure this is just coiincidental ;-)
  • 1 1
 I've folded a light weight ashima 200mm rotor when unintentionally only running 3 rotor bolts! Spits you over the bars like a stick in the spokes!
  • 1 0
 Why not use road bike handlebars in XC, that's what the affect that's the racers are going for anyway!
  • 2 0
 Too narrow for control
  • 1 0
 Its been done.

I believe there was a recent video post of this on PB (retro racing video).
  • 1 0
 Geoff ambush raced an XC raceand won last year on a drop bar XC bike.
  • 1 0
 @fabwizard: Yes. Johnny T used to smash races on his drop bar Yeti. And disc rear wheel. Current XC is bush league. (just kidding emoji)

Also, if half the rotor bolts are about time savings, XC better start mandating 2 pit stops per race. I wanna see where this actually matters. Plus, you could have all new content centred around Pit Crew Olympics.
  • 1 0
 I know that in DH it's banned, idk about XC though.
  • 1 1
 I was starting to get into the cross country scene (following the races, at least), but this makes me want to walk away from it forever
  • 1 0
 Random crazy Germans producing the one-piece integrated CF hub and brake rotor in 3, 2....
  • 1 0
 There is a lot of stuff they can do even further, but are probably limited by regulations/sponsor contracts. Once you start getting into the fringe stuff like using spectra thread for spokes, having a custom carbon blade spring fork with a carbon steerer, and custom deraillerus with bodys made from carbon fiber actuated by spectra cable, you can probably get the bikes weight down to 20 lbs.
  • 1 0
 On 2008 I was working for a mtb mag and took picture of Sam Hill's Iron Horse on Maribor. 3 Ti-bolts on rotors instead of 6.
  • 2 0
 One Rotor bolt weighs 10 Gram? Lmao
  • 1 0
 No grips! Just Hockey tape then grind off your callouses before every race...
  • 1 0
 I’d like to know what PEDs they are using, that’s the best trick of all!
  • 1 0
 that's right. when i removed the rotor bolts from my brother's bike, i was helping him save weight (rotating weight!).
  • 8 9
 “Getting your front end to maintain traction on steep”
English is not my first language so what does that mean? Rear wheel grip or handling?
  • 4 0
 Probably an effort to keep from looping out while climbing a steep ascent due to low cadence and high torque.
  • 2 5
 @seraph: I get that, I have my share of riding with tip of the saddle in my bum, I just don’t understand the use of word traction here
  • 5 3
 @WAKIdesigns: To keep the front tyre from lifting / wandering on steep climbs.
  • 2 1
 @Jacquers: May see handle bar droppers if not for extra weight it would add or fork lock out in compressed state for better climbing?
  • 4 3
 @WAKIdesigns: It's not your english, it's a questionable use of "traction."
  • 3 0
 @aljoburr: Marzocchi had a rebound lockout like you're describing, back in the early 2000s, called ECC (extension control cartridge)
  • 2 0
 @thegoodflow: I liked those things. You would lockout in the low position for climbing. Downside was that if you forgot to unlock, you were already at the bottom of the stroke with no blow-off threshold for a big hit. Seems like with remote lockouts on XC forks, that style could make a comeback.
  • 1 1
 Well, if you’re front wheel is in the air you’ll have no traction for cornering. This is very common on steep & twisty trails where the light front end pushes.
  • 3 6
 Recently saw the movie Courreur - about a belgian road racer and the shit shown there was just too much. If that's the truth about racing then bugger off. Never liked racing, never will. Mountain biking and biking as well must be for pleasure, not for destroying yourself.
  • 8 0
 There's more fun to be had than only riding your bike. Building a weightweenie bike is a extremely statisfying side of out sport for some people.
  • 3 2
 Good lord burn that stem!
  • 2 1
 Time to start trail running nude and barefoot?
  • 1 1
 They remove some of the bolts to make rotor changes quicker. Not to save weight lol
  • 3 3
 I bet the people that take rotor bolts and dust caps out are a real thrill at parties...
  • 3 5
 Yeah... every woman there be like: oh he must be up to the occasion in case I’d want a good time. Let’s send some signals and see how he responds:
- hi! Are you a racer? Would you show me some moves?
- Really? What bike do you have?
- ehm... a mountain bike?
- pfff what are you stupid? What sort?
- it’s red, you know what I just, I think I...
- it’s fine! Sorry, I can show you some moves, we’ll look at your rotors first
- what does that mean?!
- I remove 2 bolts per rotor...
- Bye
- I haven’t even... bitch... she probably rubs ceterlock. Ridiculous
  • 1 1
 Jesus. After reading this post, that's the only thing that could really save them.
  • 1 0
 Excellent article. I always love reading about the pros tricks.
  • 1 0
 No sealant seems like such a risky move.. not worth it!
  • 2 0
 UST Tires designed to not need sealant. I did La Ruta, 24 hour racing, XC with this set up and never had issues. Plus very easy to change tires mess free for conditions.
  • 1 0
 More likely it is just very little sealant.
  • 2 0
 @fabwizard: On any given ride in my area you will get 5 - 10 goathead thorns in your tire, definitely wouldn't work for me haha
  • 2 0
 @Trouterspace: UST Tires (maxxis for sure) have a very thin layer on inside designed to help seal.

I finished an xc race a few years back in Kamloops looked down at my front tire and it was covered in cactus thorns. Could not believe my tire had held air.

I used that tire for the rest of the season without issues( other than a bloody hand when i removed the tire as many of the thorns were still poking through on the inside of the tire).

Note UST tires need a UST rim to seat properly etc.. and they are slightly heavier than a TR tire due to the sealing layer inside the tire.
  • 3 0
 @fabwizard: UST w/ no sealant. Is it 2004 again?
  • 2 0
 I do love my foam grips.
  • 1 0
 Maybe they should go back to elastomers?
  • 1 0
 For real though, that pesky oil in their suspension is weighing them down!
  • 3 0
 @mtbgeartech: they could choose a lighter weight oil...
  • 2 1
 No speed holes?
  • 3 3
 What's old and dumb is now new and dumb.
  • 1 0
 upside down bars FTW
  • 6 8
 I hope they also weight themselves with this 10g accuracy ... Sorry, but this is a mountain biking's hell ...
  • 9 0
 They probably weight their food with this accuracy, so...
  • 3 2
 They do. Probably multiple times a day.
  • 1 1
 Those stems looks awful.
  • 1 3
 Removing rotor bolts is to decrease the time it takes to replace a rotor if one were to get bent not to save weight
  • 5 6
 How to make XC suck more than it already does.
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