Ask Pinkbike: Tire Pressure, Hip Packs, Dehydration, and 'Le Systeme'

Oct 10, 2018 at 10:32
by Pinkbike Staff  

Here at Pinkbike, we get inundated with all kinds of questions, ranging from the basic "Can I have stickers" to more in-depth, soul-searching types of queries like if you should pop the question or what to name your first child. Ask Pinkbike is an occasional column where we'll be hand-picking and answering questions that have been keeping readers up at night, although we'll likely steer clear of those last two and keep it more tech oriented.




Why Can't I Run Lower Tire Pressure?

Question: Thegb1212 asks in the All-Mountain/Cross-Country Forum: I have a 30mm inner width rim and [Maxxis] 2.4 EXO casing WT tires mounted up tubeless. If I even think about running lower than 27psi, my tires will start to fold over and squirm all over the place. I am not burping at those pressures, but the squirm is not confidence inspiring. I am also only 165lb. It doesn't make sense to me how folks can run pressures in the low 20s with a 'standard' tubeless set up. I am talking about non-fatbike, no Plus, just plain old 2.2 to 2.6" tires. So tell me, how can RC comfortably run 24/22 psi on 2.3" ? What am I missing? Don't get me wrong, I love the minimal flats, lower weight, and less fuss I have had with tubeless, but lower pressures aren't one benefit that I have found is possible.


bigquotesGood question. Tubeless tire pressures in the 22 to 25 psi range are not considered low, even by aggressive riders. The pressures I use are representative of most of us here at PB and the top guns I associate with on my home trails. Your combination of a 2.4-inch Maxxis WT tire with an EXO casing on a 30-millimeter rim should be plenty stiff above 25 psi, but that does not mean that you are wrong if you need more pressure to keep your tires stabilized on your rims.

Every tire and rim combination has a pressure sweet spot where the lines intersect for casing stability, traction, and suppleness. Physics dictates that larger volume tires require less pressure to achieve the same casing stiffness, and that wider rims improve lateral stability, but riding and pedaling style can trump that science.

I also weigh 165 pounds, but my riding style is such that I don't exaggerate my lean angles in the corners or put much lateral force into the frame. Some riders do, which requires stiffer casings and higher pressures to counter that off-center tire loading. You are not burping air, but still feeling tire squirm with your present rim and tire combo which suggests that you are one of them.

Before you consider purchasing new tires with thicker casings, however, be sure that your tire gauge is reading correctly. One of my floor pumps reads over four psi high, which indicates that I am running pressures around 27 to 30 psi. Now I use a Schwalbe digital air gauge to ensure accuracy. Borrow a good gauge and verify your pressures first.
RC

Topeak Shuttle Gauge Digital review
An accurate digital tire gauge, like this Topeak Shuttle, should be in every rider's tool box.




Best Hip Pack for Shorter Rides?

Question: @jkelm asks in the Bikes, Parts, and Gear forum: Looking for a hip pack to take on 1-2 hour rides. Ideally it will hold a water bottle, with enough room for my phone, keys, multi-tool and misc small items. I've looked at the Dakine Hot Laps, best curious if there are any smaller or better options out there?

bigquotesHip packs are most definitely back in fashion – just ask Lil' Wayne. He's been making the talk show rounds in support of his new album while wearing one, although its contents might be a little different than what you'd want to bring on a long ride...or maybe not.

In any case, Bontrager's Rapid Pack remains my favorite method of carrying a few tools, snacks, and a water bottle. It doesn't shift around, there are internal dividers that help with organization, and the water bottle holder is where it should be, in the center, rather than off to one side. If you already have a bottle on your bike, that center pocket is the perfect spot to stash a lightweight jacket or glasses / goggles. The fabric is fairly light, but after over a year of regular use my pack is still going strong. I'd highly recommend checking one out.
Mike Kazimer

Bontrager Rapid Pack review
Bontrager's Rapid Pack is one of the best options on the market for carrying the items needed on a short ride.




Michelin Le Systeme?

Question: @ORTOGONAL555 asks in the Downhill Forum: Hello everybody. I've recently discovered that Michelin developed a run flat setup called "Le Systeme" for DH racing at the end of the 90s~early 2000s. I'm just curious about it and I can't find more about it on the internet. If anyone has info please chime in, thanks.

bigquotes
There's a good reason why you cannot find out any information about 'Le Systeme,' and that's because it was one of the most secretive things in downhill racing, ever. Fables of riders and mechanics signing non-disclosure agreements and never being allowed to look inside, Michelin mechanics delivering the wheelsets fitted with tires and inflated to racers the morning of the race, and taking them away as soon as they were back in the pits, have circulated for years.

From the rumors I heard, there were three possibilities, one was that it was some kind of inner tube wrapped in foam, similar to things we have seen come back on the market recently: Tannus and Vittoria launched their 'Armour' system last week, and earlier this year, Mr. Wolf launched their SmartMousse. Both use a similar concept, the Tannus version uses a larger inner tube with a small volume of foam for protection, and the Mr. Wolf version uses a small diameter tube to adjust the feel and density of a larger volume foam - mostly aimed at eMTB riders, partly due to its 500g+ weight.

The second possibility is that Michelin used some kind of run-flat foam/mousse (mousse is the French word), like they used on rally cars. The foam was mounted on to the wheels and compressed when the tires were inflated to keep the characteristics of the tire the same as there was no material touching the carcass of the tire. If air was lost from the tire, the reduction in pressure allowed the foam expand, filling the tire, supporting the weight of the car, and keeping the tire on.

The third throws an extra spanner, or valve, into the works. Some people claim to have spotted an extra valve on the wheels, and there was talk of a tubular tire being placed inside the main tire, which was protected by foam. A similar idea to Schwalbe's ProCore System that that does a great job of locking the tire bead on to the rim even if the external chamber loses air, and protecting the rim from damage with its high pressure 'inner tire'.

I reached out to Michelin, and Mavic, who played a part in the project with their DeeMax wheels, and even though it's been well over a decade since it was last rumored to be in use, they still replied with a strict "no comment."


Paul Aston

Armor hybrid tire liner
The 'Armour' tube from Tannus and Vittoria could be a modern-day version of the Le Systeme from Michelin.
Smartmousse
Mr. Wolf's SmartMousse is a similar concept, but with a larger volume of foam/mousse and a smaller tube to fine tune the ride feeling.



Combating Feelings of Dehydration on Rides

Question: @zachinblack asks in the Fitness, Training and Health Forum:I am one of those guys who can never have too much water on a ride. I drink water constantly, and always feel like I need more. I know I am drinking enough, as I don't cramp up on rides, nor is my urine bright yellow, but the feeling, sensation remains. My question is this: Is there a product that will help me retain more water and hopefully diminish this feeling of constantly needing more fluids? At this point, I'd love to just be less reliant on water and make less go further, so I can forego a hydration pack and just use my on bike bottle, and at most, my hip pack's small reservoir. Am I SOL, or is there something that could help?


bigquotesI reached out to my good friend Colin Izzard, who is a coach with Carmichael Training Systems. Colin works with a lot of different athletes, including World Cup DH racers like Neko Mulally, and he suggests making sure that your everyday hydration is up to par. Starting a ride already "in the hole" is the quickest way to run yourself further into the ground. A minimum of two liters a day is recommended. If it's hot out and you're going to be doing a longer ride, increase your hydration beforehand and consider adding something that has some sodium to your water to help increase absorption.

While riding, you still have to drink water, so your idea of being less reliant on water may not be the best. You want to down 1-2 bottles an hour, and more during hot weather. When it's cold, don't forget to drink because it's still important. Ensuring you're getting 400-900mg of sodium/hour is also important to help keep you feeling good.

After riding, continue to drink water in order to replenish what you've lost. Keep up with the sodium, and a carbohydrate drink will help recovery too. Nutrition is equally important in combating feeling off, and you should always have a solid meal before riding, and try to get 200-300 calories/hour while riding.

That's a few hydration tips in short and it's certainly person and situational dependent but hopefully it helps. One thing that I've found helps me to keep hydrated when I don't want to carry a lot of supplies on a ride and there is water nearby is to bring a water filter, such as Sawyer's Mini, and stop every hour or two to filter more water. I then supplement it with a sodium/electrolyte tablet. I've successfully done quite a few longer rides with this method.

As with any other health issue, if you're not sure or consistently feeling off, check with your doctor or dietician.
Daniel Sapp

Thule Vital Hydration Pack 3L
Hydration pack can carry lots of water, but not everyone wants to ride with all that weight on their back.
Small enough to fit in your pocket and allows you to ride 'til you run out of food without having to carry gallons of water.


Must Read This Week

141 Comments

  • + 73
 Clearly asked the wrong people about "Le Systeme". Randy can hook you up with some airtight facts.
  • + 20
 You must mean Randy's French cousin, Monsieur Excité
  • + 1
 Never thought about it before till he mentioned it, drill an extra presta hole in the rim and throw an old worn out tubular tire in there, cheap and easy!
  • + 6
 @raditude: At some point we have to get Randy's birth certificate.
  • + 1
 @gordon2456: there are people who have done that, it's called ghetto procore. I've tried a variation of that with a skinny tire and tube, but I must fiddle with it some more. On youtube there is a nice video made by @andrextr and there are some tutorials by others on this site.
  • + 2
 Big shit poppin lil shit stopping
  • + 1
 @gordon2456: I always did a tube sliced down the middle as the "tape" and then left it long so i could seat the tire and use gorilla glue to attach the remaining flap to the outside of the tire. Super ghetto tubeless. She doesn't roll though.
  • + 1
 @HsawAknow: I can testify ghetto tubeless is awesome
  • + 26
 Apparently "Le Systeme" is biking's Area 51.
  • + 11
 I also don't trust reviews when they talk about normal tire/rim sizes at under 25 psi. Unless they are just surfing in organic trails it's a give-away that they are not getting above 1-2g in the corners. RC admitted as much when he talked about not exaggerating lean angles. It's good to have reviewers that see things from that average joe perspective, just gotta take it with a grain of salt.
  • + 11
 Lol... what gets me is the people (mostly in the comments) who run tubeless DH tires at low pressures... then complain about rolling resistance. Big Grin
  • + 131
 @spacemanspiff06, tire pressures are going to vary based on terrain, rider weight, and the tire's construction. To try and judge someone's riding ability based solely on the pressure they run is very strange. You want to tell Jesse Melamed that his riding is somehow suspect because he runs 19psi in the front and 21 in the rear?

There seems to be this idea floating around that higher tire pressures somehow mean that you're a better rider, something along the lines of, "I'm such a badass that I have to ride 40 psi on DH casing tires." Running unnecessarily high tire pressures is just silly - you're missing out on traction and comfort.

Find what works for you and go with it, but there's no sense in trying to put down someone's riding ability just because they have less air in their tires than you do.
  • + 134
 @mikekazimer: Yeah, but with the exchange rate, Jesse's Canadian pressures are ~25/28 psi, so it all works out...
  • - 3
 I run 19 psi front and 26 psi rear on a stock intense carbine 29er maxxis dhr2 front and rear no issue with no tire insert and no issues racing enduro over rocks. i also run 35 psi front 40 psi rear on days where its more climbing and less grip needed so like the mod says its going to vary for everyone but its totally possible depending on how and where you ride and how you distribute weight. I ride more to the back of the bike so 19psi in the front works good for me and doesn't bother me on climbs, i still leave my fork on the open setting all the time.
  • + 21
 Found the badass.
  • + 13
 @mikekazimer: Melamed is running Cush Core though isn't he? I don't know his weight but he does seem like he's on the lighter end of rider weight for EWS pros. So CC combined with DH casing and lighter rider weight but still world class and yeah I can see those tire pressures.

Rider weight and riding style are some of the biggest factors.
  • + 9
 @mikekazimer: I've always thought many riders fail to understand how suspension and tires work together. Run too high of pressure or too much compression in your fork and shock, and your tires need to compress more before the fork and shock start moving into their travel. All these people claiming to need 35 psi to prevent rim dings and the like probably just saw the article on how Richie Rude sets up his suspension a few years back, and followed suit....
  • + 12
 I wonder if it is sometimes a case of some riders just don't like the feeling of a tyre deforming and finding grip so it's not that low pressures don't work, rather they just don't like them. However if you're just riding bikeparks with high G corners then you are likely to need a bit more pressure.
  • + 5
 @mikekazimer @spacemanspiff06 I would look at the type of tire someone is running before listening to anything they have to say really. Jesse is running a 29er with 2.4 (2.5 maybe?) Dh tires and most likely cush core or something so obvs lower pressures are good to go. I would listen to his recommendations in a second cause he knows a thing or two, but if buddy riding up Fromme on single ply tires says he can run 20PSI I will probably get a second opinion. Personally I do 28-30 front and 30-32 rear so feel free to tell me if that is good or not!
  • - 4
flag mkotowski1 (Oct 23, 2018 at 14:16) (Below Threshold)
 I ride a hardtail so 19 In the rear and 18 in the front. Sure I will hit rim if I plow a rock garden without really checking my line and sometimes I do anyway but I bang out berms and hard corners and my tires don’t roll over on the rim at all at those pressures. I give up some rim
Protection for the 90 percent of the ride I don’t need it
  • - 1
 Yes, I'm sure you're a much better rider than RC... Get outta here
  • + 3
 @keeqan: definitely not good!
  • + 3
 Standard pressure starts at rider weight in pounds divided by 7. You can the add or subtract a psi or two to make the rear 2-3psi more than the front. This works for a light xc tyres or burly DH tires. However, it is too low for those of you crushing big berms at the park and it is too high for fat bikes.
  • + 26
 It's absolutely pointless to post your tire pressures without also stating your weight, tire make, model, and casing, inserts or not, rim ID, bike travel and astrological sign.
  • + 3
 @iamamodel: is that birthday suit weigh or...
  • + 1
 Sam hill says he runs 28 rear and something like 23 front. I run about the same and could probably go lower in the front but 28 PSI in the back keeps me from flatting on rides which is worth a bit of lost traction.
  • + 2
 @iamamodel: What? That puts me at only 16 psi on 26" 2.35 tires. I'm only 115 lbs, but have settled on 22-23 front, 23-26 rear depending on the trail (assuming my floor pump is accurate). Anything less and even at my featherweight status, I get more dings and feel like I'm sluggish on the bike.
  • + 10
 @mikekazimer: You really should listen to your readers, rather than the greatest riders in the world. They sound like they really know what they're talking about!
  • + 4
 I m not Randy but i run at 49 psi. Soooo fast on DH tire ( n-1 rule )
  • + 17
 @Rubberelli: zactly! All those pro's are sponsored by the air pressure cartel, and they get those PSI for free. Also they have personal mechanics that tune every PSI so they need less to do more. Then when it comes to these readers they up the price and the pressure needed. Pinkbike probably get's their PSI for free too, and @mikekazimer is just trying to stick it too these poor guys!
  • + 1
 @mikekazimer: yah modern tubeless tires are amazing allowing us to tune our tire psi’s to our weight and terrain rather than worry about blowing tubes
  • + 1
 @tgent: spacemanspiff06 most certainly rides better than RC, at least when it comes to dh and slalom.
  • + 10
 Actually, RC nailed this one. I bet that 99% of riders are looking at a crap gauge on a $30 pump with a 110 PSI range & are eyeballing 22 vs 26PSI. Get a good gauge folks.
  • + 4
 I'm running solid tires with no air, so I'm a SB (super badass).
  • + 2
 Low pressure is cool but I need air in my tires because I case jumps.
  • + 6
 @FatTonyNJ: what about just picking a pressure that you like and being a dick about it?
  • + 1
 @FatTonyNJ: yes and I am included in that... the thing is no matter what the psi reading is it still has to work for you the rider on the trail so even a consistently inaccurate gauge is fine for reference purposes...
  • + 6
 I'm 200+ lbs and was running between 37 front 39 rear all summer with tubeless DH casing. Anything less I was breaking rims. I snapped a Spank Spike Race 33 at whistler (not joking)..and blew up two other wheel sets. Had to make a choice...learn to deal with higher PSI and the sacrifices that come with it.. or keep destroying wheels. Being that I'm not I dont have the funds to continue buying new rims i chose the former. Then again there's the old saying..

"If it isn't square it isn't a DH rim"

Not even sure if that's an old saying.. anyways.. Cheers!
  • + 1
 @iamamodel: That's a nice formula! Never heard about.
So for the «old» metric world: Weight in kg divides by Pi.
  • + 1
 I run 13psi on the front and 15psi on the back for general trail riding and up it to 15psi/16psi when riding at the bikepark or on rocky terrain.
I weigh 60kg (132lbs). Front tire is a singleply Magic Mary 23x2.35 with Schwalbe procore system. The back is a a Muddy Mary 22x2.5 with DH casing and normal tube setup.
  • + 1
 @SintraFreeride: Yeah, I'm running ProCore too with about 6 bar in the tube (though I don't know how much it really matters). I run about 0.9 bar in the front tire, 1.1 bar in the rear so that's similar to what you are running. 26x2.4" in the front, 26x2.35" in the rear, also relatively light tires. I don't know how much such low pressures would add to rolling resistance really but I suppose the contribution to rolling resistance is in the amount of energy it takes to deform the tire this much. These more supple tires deform more easily so this much deformation from these takes as much energy as less deformation of a tougher tire, does it? Or is there more to it (aside from puncture resistance, of course)?
  • + 1
 @vinay: Singleply tire deform more easily than dualply. If a tire conforms to terrain then it rolls over it better instead of bouncing about.This is why the idea of running high pressure makes you roll fast is incorrect in an offroad scenario. Sure there is a point where a tire can become too soft and cause a lot of drag. I personally think knob height and shape play a more important part on rolling resistance. I recently replaced my rear tyre (used to a new) and immediately noticed the increased rolling resistance. However, I do get less spinning on the climbs and more grip on the descents. Run a semi slick back or short knob back tyre and your bike will roll much faster eg Schwalbe Razor Rock.
As for the Procore pressure I find that so long as you run it above 4.5bar it works fine.
Personally I value grip over rolling resistance because where I live you are either climbing up long steep stuff or going down long steep terrain and not much flat stuff. If I want to go faster downhill I just release the brakes!
  • + 1
 @mikekazimer: Pick a pressure and be a dick about it!
  • + 11
 On the first question, it's your gauge. I've met a ton of people who "can't ride less than 30 PSI." You measure their tires with a real pressure gauge and turns out they're running maybe 25 usually 20-25, and they just take their pump at face value. I'm 200lbs kitted and run 20 PSI front 25 PSI rear on Minnion WT's and haven't gotten flat in years here in rocky Utah. My nice parktool pump gauge reads ~30psi when the tires are actually at about 20 per my digital gauge.
  • + 5
 totally! I thought I was running 22/24psi based on my floor pump, which sounded about right (150lb rider). Now I have a good pressure gauge, it reads 17/19psi. I haven't flatted, dinged my rims, rolled tyres etc etc and I ride pretty aggressively. Get a gauge or just stick to one pump (for consistency, even if the reading is wrong). And, work out your optimal tyre pressure by trial (try different pressure on the same track repeatedly) rather than copy what the pros do.
  • + 2
 I'm 180, no gear and run similar pressures (19frt/24rr) with 2.4 tires and narrow 24mm rims. It's real rocky here and haven't flatted in over a year tubeless and even with tubes, only rarely. Funny enough, I ran lower pressures with tubes, as low as mid teens. It all depends on the terrain. If constantly doing technical climbs, on loose rock, low pressure help immensely. Best to try the extremes, both high and low and work up or down until it feels right for you, not another rider.
I would say one thing, a lot of riders are much too worried about getting flats and over compensate!
  • + 3
 I've grown to trust only my "hand-o-meter".
It's calibrated by 29 years of pumping and feeling tires without gauges.
  • + 1
 @nozes: best thing ever. I don't understand why people are obsessed with the psi thing. Hand o meter and sag o meter for me is enough.
  • + 10
 "the water bottle holder is where it should be, in the center, rather than off to one side"

I ride with a bladdered hip pack, so my opinion might not matter, but putting the bottle in the middle has always scared me a little - potential spine injury if you fall on it, or something like that. Can anyone credible confirm (or deny) that this is cause for concern?
  • + 38
 I fell backwards doing a manual (in front of about 50 people in a busy parking area) before a ride directly onto my hip pack water bottle. The bottle caved in with seemingly no resistance to the force exerted by my fat ass. Unless you're carrying a nalgene or stainless bottle for some reason, it will give before your spine does.
  • + 3
 @charmiller: Same here, but wheelie loop-out. Broke my Camelbak Podium water bottle, and did not feel good landing on it, but no injuries from it.

I may get a Poland Spring bottle, one of the Sport Cap kind, and use that instead. This way it will surely crush instead of injure your spine.
  • + 5
 I'll add my comment at well... I ride with a bottle in a central jersey pocket (so truly against my spine). I have fallen my fair share of times and I honestly have never even noticed the bottle when I crash. I agree with what was said prior to me and if you are going down, you are likely not going down parallel to your spine, ie. not landing directly on the bottle with your spine stacked above it so the bottle is likely to be pushed slightly out of the way anyways. For me, it is not a source of concern.
  • + 1
 do you even ride if you've never front flipped over your bars?
  • - 1
 @LOLWTF: LOL I wish I had a vid of the time I did that... oh wait, no... that would be so embarrassing lol.
  • + 1
 @charmiller: Same here. I've been riding with the Rapid Pack for the whole season. Don't mind sacrificing a few plastic bottles now and again. Never had a problem with the center location.
  • + 2
 You do realize its a plastic squeeze bottle? how could that ever hurt you?
  • + 5
 @ryanbpoquette: Not worried about the squeezable part - more about the lid, which is a hard disc and quite stiff in the plane perpendicular to the vertebrae. Again, it isn't relevant to me personally - I was just curious about other people's experiences.
  • + 2
 I don't typically ride with a bladder in my dakine hip bag, but they can still be very dangerous. I went otb at Snow Summit a few weeks back. Landed on my bag, broke my lower back. Keys, phone, wallet, multitool and some medical supplies were the only things in there. Keep that in mind if you're really pushing your luck with any type of hip bag.
  • + 2
 @Bluefire: I understand what you are saying. My experience is related to having it in a bib pocket, so if I ever land on the bottle, it's in a stretchy pocket that allows the bottle to move a bit more than I imagine a pack would.
  • + 1
 @Trevorjones109: Medical supplies - ironic. Sorry to hear about that, dude, and I wish you a speedy and complete recovery. I use the Dakine too. I'll try to stay rubber side up myself.
  • + 10
 Dakine Hot Laps is great. You can yank the bladder for little rides too, and just keep essentials in it. Frame bottle & the bladder is good enough for 5000 foot days, but you have to be a little thirsty the whole time...
  • + 8
 And without the bladder it fits two 12oz beers.
  • + 1
 The smaller 2L hot laps is great too. No bladder, but nice size with an option to hold a bottle off to one side (or not). It fits one tallboy with an assortment of tools, or maybe two 12oz beers if you start taping stuff to your bike. For longer rides, I bring my beeracuda.
  • + 1
 +1. The only thing I don't like is that the bladder isn't unzippable like other Hydrapak models are, so it doesn't turn inside out and dry as easily - but it's still doable. It bounces, but in a rolling manner that isn't noticeable even when fully loaded.
  • + 1
 @honda50r: p sure I can fit 3, no big deal
  • + 2
 @kmg0 - Plus it doesn't put your bottle right into the path of all the muck splashing up from the rear wheel. It surprised me that PB is always on about how bottle cages should be I side the front triangle (rather than below) to avoid splatter, and here Mike shoes us his pack with the bottle square in the giardia target zone...
  • + 2
 @g-42, this is the setup I run if a bike I'm on can't hold a water bottle, or if I'm out for a longer ride where I need more than one bottle. On super sloppy days I'll run the pack under my jersey, keeping the bottle mud free.
  • + 12
 Did anyone ask how much water that dude drinks everyday? Sounds like he needs to up his daily more so than during riding.
  • + 3
 Agreed.
  • + 2
 Or maybe get checked out for diabetes. Sodium intake during the day? Big dry or salty meals before riding?
  • + 1
 I used to always end rides on hot days with a headache, regardless of how much I drank. I am not that good in the heat I think...
I tried lots of things before settling on having a hydration tablet before a ride on a hot day. They taste gross (they are salt) but help with water retention and my headaches have gone. Obviously water intake is massive, and if you aren't drinking enough you will suffer, but if the original poster is drinking enough, it may be that he's not enough salts (or other imbalance) preventing the body from using that water efficiently?
  • + 3
 Also, the advice to eat a meal before a ride is a BAD IDEA unless it's longer than two hours before. You can eat something easily digestible and small, but not a meal, unless of course you want your legs and gut to feel like they've got lead in them.
  • + 11
 Next month please answer the question “when will you interview Randy?”
  • + 36
 Omg. When is this annoying Randy phenomenon going to end? Move on. Joke is dead
  • + 9
 @NoahsbuddyRandy: #randyaintdead
  • - 2
 is Randy Chazz'es alternate ego?
  • + 1
 The whole reason I check this site every day is to see if there's an article about Randy. I want to know how much sag he runs on his suspension.
  • + 1
 @NoahsbuddyRandy: I still don't know what the hell it's about. A tribute to freeride legend Randy Spangler I assume?
  • + 2
 @NoahsbuddyRandy: Fake Randy! Randy is no joke. Dude can send it. Comes from another planet. Turned Chuck Norris into a foam insert. Watch your back fake randy, before he turns you into his head set.
  • + 2
 @tremeer023: m.pinkbike.com/news/racing-rumors-2019-and-beyond.html
Read the top comment to see where Randy was born.
  • + 2
 I came to pinkbike for bike porn, stayed for Randy references.
  • + 1
 @casman86: ah, cheers. Missed that one.
  • + 6
 Schwalbe digital gauge is the worst gauge I have. Push it on and off the valve 10 times in a row and the readings are all over the place, higher (yes sometimes 5 psi higher than previous attempt) and 10 psi lower but then going higher than average on next attempt, and no consistency with thumb test
Schwalbe analogue gauge on my floor pump is very consistent and corresponds with thumb test
Meisner Accu-gauge (big analogue dial 0-30psi range) is very consistent and typically reads 3 psi lower than my Schwalbe floor pump
  • + 7
 Good point. Just because a gauge or pump displays high *precision* (0.1 psi, for example) does not mean it's *accurate*. Similarly, just because a gauge is digital does not mean it's accurate. It could have a really crappy pressure transducer.

I would take any new gauge I get, analog or digital, and compare it to a known-good gauge (a very high quality shop gauge for example) before trusting it.
  • + 4
 @taprider I found that you need to open/unscrew the presta valve at the max to get a good accuracy. My main problem with the schwalbe digital gauge is that somehow it uses all its battery in a month even if I use it 2 times a month…
So it stopped using it and I use roots or stones (I stop over a stone and I compress my suspensions/tyres) to estimate if the tyre is too easy too compress or too hard .
  • + 5
 Bewildering quasi-scientific info on thirst and dehydration. Noone has that high a need for sodium for short duration exercise (5hrs).
Alot more people die from overhydration than degydration in ultra-endurance events.

The short answer to your question is that you either live in Utah where it us really hot, you have diabetes, siADH, or most probably you are thirsty because uou drink too much water. Your kidneys are adapted to a high fluid intake. This happens at a molecular level in your renal tubuli. Start drinking less when you are not training 2-2.5l/day, on short rides 1.5hrs don’t bring any water an fill up when
you get home.

www.bmj.com/content/345/bmj.e4737
  • + 4
 Wrt dehydration there is a book called 'waterlogged' that dispels myths I learned in school. I used to require lots of water, generally 1.25 liters/hour. Which is too much when youre climbing in the desert. After reading the book I relaxed and waited for consequences and there were none. Now I am comfortable at 2.5-3liters over 5 hours. Turns out there is thirsty as in 'omg I can drink more' and another which is 'damn I sure would like some waters.

Also there is no evidence cramping is caused by dehydration or even electrolytes, is a 200 year old myth.
  • + 1
 I wish the jury wasn't still out on what causes cramping. I ride a ton and still hit some kind of wall at about 18-20 miles of singletrack where both legs will cramp up. I've ended up hobbling through the darkness in pain because of a 3 hour ride turning into 5 and running out of light, on multiple occasions.
  • + 4
 I still don't understand how some of these pro riders are running sub 25 psi considering some of their hucks and their speed through chunder. Granted, I am 200 lbs, but if run less than 30 psi in the rear (2.3" tubeless DH casing DHR on a 30 mm rim), as an average rider (never been on a podium) I WILL ding my rim and get a pinch flat any time I ride aggressively.
  • + 22
 Pros are smooth. They know where both their front and rear wheels are at all times and don’t smash trails like average riders do.
  • + 20
 @caradock: They also have a plentiful supply of free rims.
  • + 15
 Most of the pros aren't 200lbs. They're usually anywhere in the range of 150 to 170... those that are higher use more PSI. A 30 to 50 lb difference in weight can have a large impact on PSI. You're also running 2.3 Maxxis tires. Most pros are running 2.4 and 2.5 Maxxis or other brands that measure true or wider like a Magic Mary. Then, lots are using inserts that allow an even lower drop. Even just that small volume change has a big impact on PSI. So if you give each aspect 2 to 3 PSI, it would mean... if you could somehow lose 40lbs, increase your tire volume and add an insert...you could be easily be using sub 25 pressures in the rear. Also the role weight plays in PSI is very personal... someone like you who weighs 200 lbs and runs 30 psi will be getting around the same traction as someone who weighs 150 lbs and runs 25 psi.


It's why talking about PSI and comparing set-ups is basically totally fruitless. It changes so much based on weight, rim width, tire maker, tire width, tire volume, local terrain, a riders speed and a riders personal attitudes towards how squirmy a tire they can handle or like.

Also, unless you're spending big bucks on a gauge... from gauge to gauge, pressure readings can vary from 1 to 3 psi or more as I discovered before I bought a "better" digital gauge and realized my cheap floor pump gauge was off by 8 to 10 psi... haha!
  • + 0
 Most aren't. If u watch the details its usually a bit higher than us mortals.
  • + 1
 I have you by 40lbs and a 2.6 on a 30 ID and hucks i've gone as low as 18psi in the rear. 16 in front. Tire casing is huge for me and the goodyear and wtb 2.6 stuff is awesome. just heavy, lots of rubber in even a light 2.6
  • + 1
 @islandforlife: Yup spot on. Look at Richie who is ~210pounds...running 28ish with Cush core if I remember right.
  • + 2
 @islandforlife: All other factors being equal, a 200 lb rider running 30 psi is actually equivalent to a 150 lb rider running around 22 psi (150/200*30 = 22.5, then round down since the casing will also be a bit firmer relative to the lighter rider). These pressures should result in roughly the same size contact patch for both riders.
  • + 1
 Actually, I forgot to account for the weight of the bike. Let's assume it's a 30 lb bike, so 180/230*30 = ~23.5. So 23 psi would probably be a closer equivalent pressure. But still, I feel like most people massively underestimate the effect rider weight has on tire pressure.
  • + 1
 It is all due to rider style and preference. You look at some pros and see that they are running around 20psi and others who are running 32psi.
  • + 2
 Good tire question! Not all tires, rims and rider styles the same. Everyone has a preference. I have a 35mm rim with 2.5” rubber and I still run my pressure at 25 and 27 psi. I’ve tried to go lower but for my weight and riding style the tire just gets to squirmy
  • + 2
 So I reached out to some "coach" from CTS who told me about the real "System". There are 2 components to the "System":

1) Pay CTS for coaching.....waaaaay too much money.

2) This is the important part of the "System"-use some octane booster. EPO, HGH, even some old school anabolics if you won't get tested. It's what Chris Carmichael did to get his results, as well as that Lance Johnson guy. This "System" works, and if you get results and don't get caught, you might even build an overpriced coaching business based on the results of other dopers (even if THEY get caught eventually).
  • + 2
 Id love for someone to expand the hydration topic to that of headaches. I dont get thirsty on rides, but whether I drink gallons before a ride or not, if its hot and Im pushing, Im going to get a headache. The only way to avoid this has been too much salt, or pre-gaming with ibuprofen, which isnt great either. Oddly enough, when I ride during the winter, no headaches. I cant ride naked, so how does one convince the body to “chill out” when Im practically suffering with accute heat stroke on every summer ride?
  • + 2
 can't or won't? Wink
  • + 1
 @rrolly: haha my Doc actually just suggested I try to taking Magnesium supplements before rides.
  • + 2
 Yes 22F and 25R and after some km got to take some air on them cause they inflate by them selfs a phew psi ,like who the hell is inflating my tires ,it’s strange but it’s real they gain air after some km ,and yes tire pressure makes a lot but a lot difference in a ride it’s almost like magic ,I can deal with a not so perfect suspension balance but with over or under pressure tires no thanks
  • + 1
 I like hip packs. I use the Race face Rip strip and it's great ! I just don't get the concept of putting water on the hip pack. The whole point of the process is to free your back of as much weight as possible, not adding an extra 500g. Put the water bottle on the bike, let it carry the load. Having a pocket for tucking in your jacket is more useful in my opinion (Evoc's 1L hip pack looks great for that).
  • + 1
 I'm a bit confused about this: "Physics dictates that larger volume tires require less pressure to achieve the same casing stiffness, and that wider rims improve lateral stability, but riding and pedaling style can trump that science."

In my mind, a 2.6 inch tire will need equal or more pressure than a 2.3 on the same rim, to provide the same lateral stiffness. Or is only referring to vertical impact i.e. rim protection?
  • + 5
 Pressure is per unit of area. Think about it in terms of air volume.
  • + 3
 If you consider the tire to be a pressure vessel, the stress in the tire casing will be roughly pressureXtireradius/tirethickness. Sigma=pr/t. The large the tire radius, the more stress in the casing, which resists deformation.

This is an odd analogy, but if you blow up a balloon, the air inside it is all at the same pressure. It is somewhat hard to deform the main balloon if you poke it, but it is very easy to deform that little thing (stem?) that hangs off the main balloon where you blow it up. The radius of the balloon at the stem is small, so the stress in the balloon rubber is also small, so it is easy to deform. Bigger tire radius results in a harder to deform casing, all else equal.
  • + 1
 The bigger volume tires have more air for the same pressure... you're thinking the same air... not pressure. If the same tires are at the same pressure, width will be practically irrelevant. (right? Did I miss something?)
  • + 2
 @mtbikeaddict: yes you did. For example:, a 23mm road tire at 100psi will still deflect fairly easily under a rider's weight because that pressure is only acting upon about 50 millimeters of casing. A 2.35-inch tire at 100psi (if you could achieve that without bending the rim flanges open) would not compress noticeably under the same weight and would ride like solid oak. The same pressure reacting against roughly four times the casing area creates much more tension.
  • + 1
 @RichardCunningham: Facepalm I think my train of thought started going that direction in the beginning... But then I wasn't quite sure what I was saying... I totally missed that, thanks for pointing it out and making it easy to understand. Big Grin
  • + 4
 Oh wow my question got into a pinkbike article. Thanks for the answer @paulaston and pinkbike, this was very nice.
  • + 2
 Drink water until it's almost uncomfortable right before leaving for your ride. For me that puts one bottle in my system, so with one on my bike, that's a 2-3 hour ride, no problem.
  • + 43
 And you can piss it all out as ballast if you're about to case a jump?
  • + 1
 @Bluefire: Comment Of the Day
  • + 1
 @Thegb1212 get a new tyre pressure gauge.

They get clogged up with sealant and start giving messed up readings. I'm 210# (93kg) and run my EXOs at 21F and 24R on 29 internal rims without any problems. Granted it isn't rocky where I ride but I certainly don't have any sidewall squirm.
  • + 1
 What drinks are a good supplement for water and gatorade? I like the idea of replacing lost electrolytes, but dislike the high sugar content of gatorade or vitamin water. Is there an electrolyte-rich drink out there without tons of sugar?
  • + 2
 I'm right there with you and my wife recently turned me on to Nuun tablets. I drop one into water after any big ride (and after other sports) and they recharge me very well without all the sugar I hated. I'll note that I did experiment with them pre-ride and during and they didn't do as much for me, but YMMV.

I also recommend pickle or olive juice. As a bonus, I eat the pickles or olives that get in the way.
  • + 1
 I'm not sure of the sugar content, but I really do like Skratch labs. Other companies that make electrolyte tablets include SIS, GU, and as mentioned below, Nuun. There are a bunch of other brands as well, but those stick out to me. Another option is something like an isotonic gel (such as those made by SIS), but those are also fairly sweet.

If you really want low sugar, Coconut water (Potassium rich) and a pinch of salt (sodium rich). The advantage of this is you get more potassium, which is often minimal in electrolyte tablets, powders, or gels
  • + 1
 NUUN is great stuff, very helpful. Bananas are helpful too I find.
  • + 1
 There is no win bro, average short ride is at least 2 hours, that small water bottle is gone in two gulps.The Evoc 2 liter hipster is pretty good, and looks far better than a back pack.
  • + 1
 This may well be the best hip pack out there. Compact, lightweight, comfortable, roomy enough.

labaustere.com/collections/frontpage/products/minimize-hydration-lumbar-pack
  • + 1
 For the dehydrated guy, I'm not sure if this is really right for you but this stuff does claim to do what you are asking for: osmonutrition.com/product/preload-hydration-for-men
  • + 3
 I'm so glad fanny packs are back in style. The one I've been using since 1987 was getting a bit ragged around the edges.
  • + 1
 Coming from moto - I'm always surprised there's no full mousse system available for MTB right now. One that's competitive to other systems. We exclusively ran mousses for moto - flats were then impossible.
  • + 2
 Am I the only one who drinks beer on rides, runs 40 psi, and doesn't use tire inserts?
  • + 1
 +1 for the Rapid Pack. Holds just enough for 1-2 hour rides, and the build quality is great. Has a key clip inside, too, which is really useful.
  • + 1
 For the water/thirst issue, I've found that chewing gum makes me drink less water. I still drink more than I need but it helps!
  • + 4
 Not sure if serious...Gum just triggers your gustatory reflex. You're not hydrating yourself with your own saliva. You know that, right?
  • + 1
 @sngltrkmnd: not truly hydration, but the illusion helps. Hence why back in the day in the West people would suck on a pebble or something...
  • + 1
 Judging from the dirt on that fanny pack looks like he took a digger in the dirt. Must feel great to land with your lumbar onto a water bottle.
  • + 0
 tire squirm is usually an issue with anything larger than 2.4 and non DH casing , tried several things , too much air rides like crap , there is a fine line that is easy to cross
  • + 2
 Don't be a slave to numbers, ditch the tyre pressure gauge and go by feel.
  • + 1
 Fanny pack mousse inflation ? I Think I’m a little Randy , I’ll be right back
  • + 1
 Spesh butcher 2.6
Stan’s sentry 32
Fox 36 160
165 lbs
17 psi
Happy
  • + 1
 Nice way to present ads))))))
  • + 1
 I like Ass Bag.
  • + 1
 Gatorade powder.
  • - 3
 Best Hip Pack for Shorter Rides?

There is no best hip pack because they are all bro.

(waits for down votes)

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