Ask Pinkbike: Over-Forking, Missing Bolts & Anti-Squat Energy

Apr 28, 2020
by Dan Roberts  

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.







Over-Forking Geometry Changes

Question: @lyfcycles asks in the All Mountain, Enduro & Cross-Country Forum: Are there any hard numbers on what over forking a bike by 10mm does to the geometry, HA, BB height, STA etc? I'm looking at picking up a 2020 Top Fuel 8 but immediately replacing the fork. Trek says the frame is designed to be able to take a 130 and since I'm buying a fork anyway I thought maybe I'd get a 34 and just have the air springs for 120 and 130. Just trying to get an idea on how much it is going to slack out the HA and STA mostly.


bigquotesLong forking is brilliant. More party up front and potentially more aggressive geometry come from it. But it really depends on the bike's standard geometry as to whether it will work and how much it would change the geometry by.

Taking a standard 2020 Trek Top Fuel 8, there's a Rock Shox Recon Gold RL fork with 46mm offset. This is actually a little different in dimensions as to what Trek state in their geometry of the bike. They quote a 44mm offset, which points at the bike being designed around a Fox fork.

Rock Shox and Fox don't always have the same dimensions for forks with the same travel, and in the case of the 120mm forks the Rock Shox is a shorter axle to crown with a longer offset. So, truth be told, the geometry on your bike as you got it is ever so slightly different to that quoted. That's nitpicking, though, and only makes the head and seat angles 0.1 degrees steeper and changes the rear, stack, bottom bracket height and wheelbase by a single millimeter.

Adding in the 130mm travel 34 changes things a bit more, and guessing that you'd be buying a standard 34, rather than the Step Cast version, which isn't available in 130mm travel, you'd actually have a fairly efficient packaging of 130mm travel in a small axle to crown.

Statically, no rider on the bike, comparing your exact bike spec to a 130mm travel Fox 34 your head and seat angles would slacken half a degree, your BB would raise by 4mm, your reach would get 6mm shorter and your stack would increase 5mm.

For setup, if you took the same 15% fork sag between 120mm and 130mm travel you'd lose 1mm more due to it, but the extra 8mm of fork is still big enough to give a geometry change.

Those are all relatively small changes, but if you're in-tune with your bike then they could be something that you might pick up. Over the top of 10mm more party that is.

Long fork geometry adjust 2D drawing
Long-forking bikes is a common scenario, although, depending on the bike, the geometry changes that arise from it can be good or bad.







Bolts and Stuff

Question: @recklessrye asks in the Downhill Forum: Does anyone out there have any clues as to where to find those specific bolts for older bike, without having to call every local bike shop. In particular, I need a rear pivot bolt for a 2006 Norco B-Line. It’s sad because otherwise the bike is in good shape and would be great to save for my youngest son.

bigquotesBrands would normally have to keep a bunch of spares for bikes that were produced within the last five years. But, given that your bike is from 2006 it's pretty far out of that period. You mentioned not wanting to call every local bike shop, but I'd still recommend trying the Norco dealer closest to you. If they don't have the part in stock, it's possible they could order it in for you, or at least provide you with the exact dimensions.

Failing that, if it's the rear pivot bolt that you're after, you could take the bolt out from the other side down to a machine shop and either see about an existing standard bolt that could fit for the length, diameter, thread and head. Worst case, I imagine they could machine up a new bolt, although it would be the most expensive option.

Once upon a time, while out on holiday in France, the same bolt fell out of my Intense M1, and myself and a bunch of friends managed to find a standard bolt that fit like a dream. It came from the back of a road sign of all places. So, there might be a standard option out there for you.

Failing that, perhaps one of the Pinkbike readers out there has exactly what you need?


2006 Norco B-line for sale
Keeping old bikes like this 2006 Norco B-line going is a worthy endeavor, but getting hold of specific parts or hardware can be really tricky with these older generation bikes.







Anti-Squat & Waste of Energy

Question: @Will-narayan asks in the Mechanic's Lounge Forum: Is having anti-squat as much a waste of energy as pedal bob?


bigquotesWill-narayan asked, in a pretty extensive post, about the idea that if energy is lost to heat in the damper due to pedal bob, then wouldn't the forces of anti-squat also rob the same energy and make it harder to pedal. It's a really interesting question. One that can get very deep into physics quickly and to have a definitive answer needs a good dose of calculation, and assumption, to come out with numbers behind the answer.

Rather than have the idea that with anti-squat a bike would be harder to pedal, let's say that the amount of energy input into the bike system is fixed, and look at where it could be lost to instead of what you really want, the bike going forwards.

A bike with a lot of pedal bob, potentially because of very low anti-squat levels, would indeed have some of the rider input energy lost in compressing the shock when you try to accelerate forwards. While the acceleration might be the same as a bike with higher anti-squat, the reaction of the system due to the acceleration and ensuing load transfer would be very different.

A bike with enough anti-squat to counteract the tendency to squat due to the load transfer would also need some energy taken from the rider to have this. The load transfer due to the acceleration still happens, just that it results in less or no squat. The response from the bike due to the acceleration is then very different to a bike with lots of pedal bob.

Physically quantifying how much energy is taken from the rider in each case is something I haven't done, unfortunately. I'd need the assistance from some of the bigger minds in the bike industry to have accurate numbers and so a good comparison.

But overall, it's more favourable to have a bike that doesn't bob excessively when we pedal. Having had the chance to ride bikes with removable idlers, and so have the exact same bike and setup just with altered chain lines and anti-squat amounts, I can say with complete confidence that it was a lot more exhausting riding around on the bike with drastically reduced anti-squat. So much of the energy invested in the system was spent in squashing the suspension rather than going in the direction I wanted to go.

We've already looked a lot at anti-squat in our Enginerding article, and there will be more in the future on different topics. But your comparison of the two scenarios and energy lost is something that we'll look at calculating and definitively commenting on.


Anti-squat is one way of combating the effects of load transfer when we accelerate, but it does need some energy to do it. But how much energy compared to that lost in suspension bob on a bike with low levels of anti-squat?







110 Comments

  • 55 0
 The bolts and stuff reminds me of my brother, he broke a lower pivot bolt on his 2015 Diamondback DB8, messaged Diamondback, got told shit all and that his bike isn't supported anymore, so he went to Home Depot, found a monster of a bolt that fits in the width, greased it up and stuck it in with a load of washers, the bike runs like new again.
  • 23 0
 Snapped a shock mount bolt on my old Kona Process a day before a race. I thought I was screwed and started driving home. Saw an Ace Hardware store and just for the hell of it stopped to see if I could rig something up and sure enough they had a metric bolt that worked, stainless steel too! Ran that bolt for years.
  • 3 0
 Totally did the same with my DH bike. Random bolt in the garage worked wonders on the shock.
  • 55 0
 Wow - not supporting a 2015? Thats pretty pathetic by Diamondback.
  • 16 0
 I was building up a GT gravel bike and needed some hardware, only to be told by Doral to essentially go piss up a rope. And this was for a frame model they currently sold, not some long dead model. Some brands really freaking suck when it comes to getting spares, and it's definitely a factor when I consider switching brands.
  • 4 1
 @ratedgg13: They only produced the bike for 2 years. This was also after Diamondback had been bought out by Regent LP, which may have been most of the reason why it was not supported. Not 100% sure of the details, and it isn't an excuse. it is pretty pathetic they wouldn't carry something like that though.
  • 8 0
 @matadorCE: Big companies have big supply chains and the amount of effort for them to chase down, order, receive, ship and charge you is not worth it to them. Plus you probably talked to some minimum wage call center person that probably doesn't even know what a gravel bike is.

It's poor customer service for sure but that's the business they are in.

In my experience, the best way to get something small (like hardware) from some of this big brands is to find the regional sales rep or the brand marketing person. They tend to be riders and are usually willing to help out within reason.
  • 2 0
 @Paddock22: I tried reaching out on my own and also going through a LBS a lot of GTs at the time, same result with both. I needed a bracket to mount the front derailleur and the frame cable guides. I ended up taking my dremel to a bracket from a Giant and lucked out in finding some cable guides on ebay.
  • 12 1
 @Paddock22: That's why I really like smaller companies like Knolly. They sell all of the hardware for their bikes on their web site and will help support you any way they can.
  • 10 0
 Take your bolt to a local fastenal store. They’ll get you an exact replacement often in a better grade....
  • 1 0
 Yeah at least it was just a steel shock bolt. Imagine trying to find a hollow alloy pivot bolt off a 2006 vintage frame made by a company that's changed hands eleventeen times since. Then you would be SOL.
  • 3 3
 It seems fairly common for each brand of bike to have their own custom bolts (commonly found thread pitch sizes just custom machined lengths/designs/materials). Even knowing someone with access to a lathe and some basic machining skills could help if you aren't able to find a replacement fastner in a hardware store. I'd be more worried about riding an old aluminum frame and the fatigue life left in it. There's a reason why there are so many old lugged steel frame 10 speeds on craigslist, they last a long time!
  • 2 1
 @coyotecycleworks: you trying to plug your frames here????
  • 3 0
 www.mcmaster.com these guys in the US have the mother load of selection of fasteners
  • 4 0
 @gaffney92: them and msc direct. fastenal shops are all across North America in most medium sized cities.
  • 1 0
 @scotttherider: I second Fastenal. They are all over the place and their physical locations let you walk in and buy/pick something up pretty easily.
  • 1 0
 @Paddock22: you can’t go into the locations right now but they will come outside and go get you the bolts you need.
  • 1 0
 @supertack: I have saved many parts like that, just gotta look for it!!!
  • 2 0
 @scotttherider: We use common fasteners (mostly allen drive cap screws) for this very reason. I'll plug all steel frame manufacturers here, it's just a better all around material to make frames out of. The reason many bike companies use aluminum (or aluminium depending on your region of the world) is it's cheaper to form/machine so it's easier to do mass production. Aluminum will eventually fail pure and simple. A great example in a critical application would be the amount of take-off and landing cycles a particular type of airliner can do before the airframe needs to be retired. The cost of manufacturing/efficiency/weight savings are worth having to cycle out after x-amount of use, but at the end of the day it gets retired/replaced. Now the stakes are nowhere near as high on a bicycle but I wouldn't want to be going through a rowdy rock section on a 15 year old frame and have my head tube snap would you?
  • 1 0
 It works because no one hs a 15 year old frame, innit. They are consumable toys at the end of the day. My dad would go all right on a steel frame. He's the only person I know who would want to keep a bike for that long.
  • 1 0
 @coyotecycleworks: On the other had, only the pros are hucking to flat every single day and riding AL frames so I don't think the average rider will get even close to the life cycle limit .
  • 1 0
 @coyotecycleworks: I’m well aware of material fatigue. I’m a certified welding inspector on top of having been a welder for coming up on 20 years this September. I also once upon a time from 04-06 welded bike frames at SAPA Inc on SC frames, Turner, Ellsworth, Cervelo and Knolly at the end. I was just flicking you shit. I’ve always wanted to weld and build my own frame but have never had the time to do so.
  • 1 0
 @scotttherider: Hey I'm a CWI as well! Small world I've been working as a fabricator/welder/weld inspector for the aerospace industry the last 15 years. What industry do you work for?
  • 1 0
 @coyotecycleworks: check out my pics and videos. I work in the hydroelectric Field. What code did you do your CWI with? I did D1.1!
  • 1 0
 @scotttherider: Nice will do. I got mine in D17.1, I have a copy of D1.1 and I'm glad I didn't have to test with that!
  • 1 0
 @coyotecycleworks: it’s not that bad. Less questions in the code section.
  • 25 0
 If you had a magic bike that always had the perfect amount of anti-squat to prevent any pedal bob, you would not be able to perceive any difference between riding that bike up a paved road or riding a hardtail up that same road. Your body and the bike would remain in exactly the same position whether you're riding the hardtail or the magic perfect anti-squat bike. Since the movement is exactly the same, the amount work and therefore the amount of energy required is exactly the same. That said, even on the magic bike you'll still lose some energy to the damper and friction if the suspension has to absorb any bumps.
  • 13 1
 absolutely,
No movement + no heat = no energy
  • 7 3
 @faul: Heat is energy, movement is not.

Energy/Work = Force x Displacement along the acting line.
  • 5 3
 Canfield Balance Formula comes about as close to this as we could hope. It does feel remarkably similar to pedaling my rack-laden commuter bike on pavement.
  • 17 2
 That`s why I say: get a hardtail, bordel de merde.
  • 7 0
 @Loche: Yes, but, energy/work=Force x 0, if there is no movement. so energy=0. No energy.
It's a simplification easier to understand, for those fearing their high antisquat bikes are somewhat less efficient.
  • 41 10
 The recent anti squat talking really amuses me. If I had a son in his early 20s who came to me and asked me: Dad? How much Anti squat does my bike have? - I’d tell him to shut the hell up and ride his bike, bring me some PR , show me some sideways action or I’ll sell his bike.
  • 11 2
 We also shouldn't disregard how much energy is wasted on a hardtail traveling over sharp edges like roots, rocks, and small trees. They can suck up your momentum pretty quickly and occasionally bring you almost to a stop.
Hopping over them may be simple, but that takes even more energy to do. I still think my hardtail was the most efficient bike I had as a whole, but some rooty extended climbs on trails near me are much easier and take much less energy on my short travel DW-link bike.

My hardtail was also a 26"...Im sure that made a difference too. It wasa very playful bike and a blast to ride. I will likely build another hardtail in the future with bigger wheels.
  • 2 1
 @Warburrito: Exactly this. I've got so used to mushy Enduro's that I ride a bike with a lockout or high anti-squat and I feel more tired going over little bumps and just generally pedaling. I often wonder if it's because the shock movement softens the power stroke slightly.
I'd like to know how efficient the high anti squat is pedaling over small bumps versus a couch like my coil shock Enduro. A bike with high anti squat means you have the bike and the rider having to be lifted over the bump.
  • 9 3
 @WAKIdesigns: an early 20s son trying to have a substantive conversation with his father about a hobby they both (seemingly) love....and you’d tell him to stfu. Good on ya.
  • 3 4
 @nvranka: sensitive much?
  • 1 0
 Does running a more sensitive, open compression shock with more sag better match with a high-anti-squat design? I think it's interesting that a lot of XC bikes don't have tons of anti-squat.
  • 1 0
 @PHeller: I think that can be accurate. My DW-link setup seems to fit that description. Lower compression, low shock pressure, high sag, more anti-squat. Nice small bump compliance without bobbing.
  • 7 0
 @WAKIdesigns: What if you had a son in his early 20s who came to you and asked you: Dad? How much bloody time do you waste trying to look clever writing comments on PB? Dad why don’t you shut the hell up and ride your bike, bring me some PR , show me some sideways action or I’ll delete your login (and send you to an old people’s home).

Ho hum, only kidding Waki...
  • 3 0
 @aps62: The PB comments section has a strong undercurrent of aggressive close-mindedness. I would imagine that a group of the loudest voices here in the PB comments section come here with the goal of being heard as a commanding voice that will influence others towards their opinions. Waki's offhand comment about a parent crushing curiosity and establishing dominance fits in perfectly with the ethos of the PB comment section, in fact, I'd say it is really the perfect comment to encapsulate the attitude of the PB comments section. Not everyone on here is here with such goals of course. There are some great discussions and some very open questions that motivate people to think.
(this is not an attack on WAKI- the guy has lots of good and bad contributions to PB and I often like reading his comments)
  • 4 2
 @WheelNut: Crushing curiosity?! Pardon me but in 99% of cases (save people who actually will be or are engineers working in related field) being overly interested in suspension kinematic of bikes in 2020 is not a sign of curiosity but riding impotence and raging cluelessness. The single best thing about guys I ride with lately on dirt jumps is that unlike majority of MTB nerds, they don’t give a shit about some silly tech, their thinking is rather simple: the only way to be better and faster is to practice and build environment for practice. They just fkng ride. Being around them is strikingly refreshing. Their simple yet filled with hard work way of life is rejuvenating. I cannot express how MTB community is ravaged by paralysis by analysis. Hence, I would do my utter best to tell my offspring to focus on riding in order to get better at riding instead of looking at some dumb sht only bike engineers, mechanics and an army of losers find attractive. Sorry...
  • 5 0
 @WAKIdesigns: some people are interested in physics and kinematics...I may not be one of them, but I don’t understand why you would hope your son is a ‘bro’ ready to full send rather than a thinker.

I have friends who just ride, I have friends who like to tinker and talk tech...some are good and some bad on both sides.

You’re right that the majority of rippers don’t get bogged down with the details, but that doesn’t mean there’s anything wrong with the details or taking interest in them...
  • 6 0
 @WAKIdesigns: No need to apologize. Just want to impress upon you that the "Shut up and ride. No math!" is actually discouraging to some people, because for some of us we find the mechanics of the bike fascinating and learning how everything works is quite fulfilling. Mountain biking is a hobby after all- the whole point is personal enjoyment. There are lots of different types of people out there. Some love to tinker, investigate, and take things apart and some don't give a shit about knowing that stuff and just want to ride the bike. No harm in being interested in how things work and equally there is no harm in just wanting to shred. Telling someone else what they should value in mountain biking is like shouting at a brick wall. It won't change anything.
  • 4 0
 @WAKIdesigns: Some of us just enjoy nerding out on this stuff regardless of whether it will improve our riding or not.
  • 19 1
 What's the optimum fork offset for the Grim Donut? ....Or was it the Glum Danish...been so long...
  • 22 0
 The Melancholy Trifle is designed around a 3mm offset but no-one makes one until 2042 so Levey's unborn child will do the full review.
  • 2 1
 Gash doberge?
  • 9 0
 44mm, but you install it backwards.
  • 1 0
 @conoat: 36" UBERBOOST
  • 2 0
 @conoat: So basically every fork installed on a Walmart bike?
  • 3 0
 @ninjatarian: lol i remeber seeing manitou forks installed backwards lololololol
  • 17 1
 Brain hurts. Must ride...
  • 11 0
 Taking the main pivot bolt out of my Titus el guapo to replace bearings and the hollow ally bolt snapped, leaving the threaded half of it in the opposite chainstay, and no stock worldwide for the aluminium bolt and a conundrum to get what was left of it it out of the frame; local machine shop got the broken threaded part out, rechased the now stripped thread for me in a larger thread and fabricated a solid steel pivot bolt with a 17mm hex head rather than the stupid 6mm allen key on the original. Still going strong after 2 years and 3 bearing changes, cost me the grand total of £50. Otherwise would have been throwing away a perfectly good frame.

Think it's broken? Ask your local machine shop, they know what they're doing and it might save you hundreds....
  • 11 0
 McMaster-Carr is a great place for weird bolts if you live in the USA. Would be the first place i'd check.
  • 1 0
 McMaster has a HUGE supply of everything fastener related. I'd be surprised if they couldn't supply some sort of solution. NOW I'm sure there are a few instances where they can't help as there are always the exceptions, but for the most part they are my goto.
  • 8 2
 I used to overfork bikes when I didn’t really understand or notice the negatives it causes. Namely a higher BB negatively impacts cornering and centre of gravity, gives you a slacker seat angle which may cause problems with you knees and back on some already slack seat angled frames, and when climbing up steeps its harder to keep the front end down.

There are usually much better ways to create a more confident bike:
Namely an angleset or maybe even offset bushings.

And if you just want more travel without affecting geo too much then look a a fork with a shorter a-c measurement like mrp’s offerings. 10mm free vs rockshox
  • 2 0
 Agree...I've done it on several bikes and beyond 10 or 20mm it gets to be too much. Offset bushings can bring your BB down to compensate, but then your SA is way off and your pedals are too far forward. You can move your seat forward, but then your reach feels significantly decreased. I've had luck with small changes, but past a certain point things get too weird quickly.
  • 2 0
 Angleset + overfork ftw. Even offset bushings to go that step further. All dependant if your frame allows for these changes.
  • 8 0
 The French Police Nationale want that bolt back...
  • 2 0
 You mean the Gendarmerie?
  • 3 0
 @nozes: Oh, is that the proper name? I did try to find out what the current title was, but there were several different kinds of police, and I am not sure the military kind would be the ones to handle this matter. But thank You for the correction.
  • 2 0
 @rosemarywheel: that would prolly be a job for either the police municipal or the gendarmerie. Gendarmes have indeed a military statute but it’s not exactly NCIS lol
  • 1 0
 @rosemarywheel: basically, the police nationale is working in cities whereas the gendarmerie is working in small cities and countryside. So you might be right!
  • 1 0
 @lecriquet: Well, hopefully they wont take him away...if it were me, I would use it as an excuse to take a holiday to France and replace the bolt (I am sure it has already been done) lucky it fit, though
  • 5 1
 "Over-Forking" allows you to run with a little more sag, and a plusher ride. I've heard in many posts on many threads, in many forums that over forking potentially voids your warranty, and the frame will break because "it wasn't designed" to run that much travel. Seriously... has anyone snapped their frame because they ran too much travel?
  • 3 0
 Depends on the manufacturer. Many brands design their frames to accept +/- 10 or 20 mm of travel. Throwing a 180mm fork on an XC bike obviously will present problems, but bumping from 130 to 140mm on most bike is no issue. If you're concerned, just email the brand.
  • 2 0
 Quite. I used to have a Corsair Konig (designed for 130mm) with a Totem Dual Position air on it - 150/180mm travel. Yes, I used to run it in 180mm mode on downhills. We won't talk about the handling but yes, it worked and no, it never broke.
  • 1 0
 I developed a crack at the downtube/headtube intersection using a 150mm fork on a bike designed for 120-130mm. It was an adjustable travel fork (Fox Talus); rode at 120/140 for a couple years without an issue, bumped it up to 130/150 and the crack appeared... That said, it was a "light trail" bike, and I probably abused it in ways it wasn't designed for.
  • 5 1
 Went from a good hardtail to an old Full sus. I've started breaking all my records on strava by a significant margin.
The anti-squat is good, but not perfect on a triple chainring on a 2011 way overforked (130/100mm) xc bike.
My take is that you preserve so much energy just letting your bike take the small bumps instead of easying the bum out of the saddle.
  • 1 0
 Sounds stupid, but I threw a suspension post on my last hardtail and liked it. It helped some and didn't seem to make it less efficient.
  • 1 1
 If you're surprised at what a swap from an ht to a 130ish bike does for your times/speed/comfort/confidence, wait till u go to a 160 travel rig with up to date geometry. Feels like the world opens up.
  • 5 0
 @ranke: he’s talking about climbing

160travel is not the important part either, it’s solely the geo.
  • 2 3
 @nvranka: why would anyone cares about their climbing times?
Smile
  • 3 0
 @ranke: I care about saving energy on the climbs so I can smash the descents....

I realize the OP referenced beating strava times, but the point stands regardless.

I’ve never experienced a version of myself that could attack on the dh bike but was a slug on my AM loops, fitness and shredding go hand in hand imo.

If you just want to get sideways at the park I get it, but I don’t leave close to one Frown
  • 2 0
 @Warburrito: It doesn't sound stupid. Stupid is road tires on a downhill course! The efficiency, in my opinion, is related to the pedals, not the seat. Cheers!
  • 1 0
 @ranke: Oh boy, its a 100mm frame with 130mm fork and 26" wheels. My dream is a 29er with 150mm frame 170mm fork! Everything we ride here is either backroads or extreme junk that rain water has digged, with lots of rocks.
  • 1 0
 @nvranka: Geo will make a HUGE improovement if I get my hands on a recent ish bike. Since prices are crazy here, it will take some years...
  • 2 0
 A rule-of-thumb I've found accurate for over shocking is 20mm more travel slackens the headtube angle about a degree. Bottom bracket height increases about 10mm. These vary with different wheelbase and chainstay lengths. What I would like to find are more alternative suspension knuckles to modify rear wheel travel and BB height. There are a few out there. It would be nice if manufacturers had options for ride adjustment. Raise the BB and add travel for rocky terrain, lower the BB for fast, flowy loam.
  • 7 1
 Those thing exists.
Rocky mountain have the "ride 9" or something like that.
It's useful the firts 4 rides, when you play with the adjustments. then it becomes boring , you put it in the most "aggressive" position and you don't touch it anymore.
  • 2 1
 @faul: I think the best thing about flip chips is it allows a company to sell a more aggressive bike without losing sales to those that are afraid of more aggressive geometry. I’ve been pretty much over forking my bikes for 20 years by 10-20mm to get the ride feel I want. Unfortunately, that often took a too slack SA and made it slacker, but I’d just slam the seat forward to compensate. The only bike I think I didn’t over fork was the OG Intense Tracer because it had a second shock mount to slacken the HA from 71 to 69. Anglesets work to help this but only the Works ones from Britain are worth a damn and aren’t the easiest to get stateside.
  • 2 0
 us.misumi-ec.com is a fantastic resource for affordable custom Metric hardware.
most fasteners are offered in a few different materials and you can even find funky stuff like shouldered bolts with low heads.
The best part about Misumi is that you can order singles of bolts without paying OTA.
I think someone else already mentioned McMaster for Standard hardware; pricey, but whatever gets you rolling!
  • 2 0
 I could be wrong, but I don't think preventing squat (anti-squat) necessarily consumes energy as you are suggesting.

Let's imagine the simplest system. To get rid of rider movements and weight transfers like legs flailing around we replace the rider with an electric motor on the crank. The bike has 100% anti squat. When we turn the motor on, the bike goes forward and has no vertical motion. If there is no vertical motion then no work is done. If no work was done in that axis then no power was consumed. It just zeroes out. Now imagine a bike with 200% antisquat. The bike goes from sag, to less than sag when we turn the motor on. Work was definitely done in that period (some of which converts to heat in the suspension). Now imagine it's a meatbag pedaling. You are like the worlds shittiest electric motor, you output a sinusoidal power form. The suspension anti-bobs you up as you push down on the pedal, then as you go past 12-6 o'clock the suspension goes back to sag and then you repeat that 180 times a second for a cadence of 90. On flat ground your vertical axis would look like a pogo stick. That's a lot of work you are doing which doesn't make you go any faster!

0% antisquat is the same thing but in reverse (this is harder to imagine, which is why I started with the 200% example). A lot of bikes have more than 100% antisquat (at least in certain gear/travel combinations).

So while there is such a thing as too little anti-squat. There is also, definitely, such a thing as too much.

"But my bike has 100% antisquat and I still see my shock moving!" Yes, cause there is more going on than just your pedal force input. You are literally flailing around on top of the bike, so that causes shock movement too as you are changing the center of gravity of the system etc. This is why we should all ride rigid bikes and enduro is dumb. QED

Now is that everything going on? No, but I think it's a pretty quick and simple explanation of a lot that is happening.
  • 1 0
 I like the meatbag flailing around description. A bit easier to envisage than my previous description of a quarter-horsepower engine moving violently all over the place. Totally right though, there is too much and too little. It's all about finding the balance, which is harder than it sounds when you factor in all the other elements that need balancing!
  • 2 0
 "your reach would get 6mm shorter and your stack would increase 5mm"

How is reach going to affected more than stack? Head tube angles are still above 45, so an increase in the fork axle-to-crown (hypotenuse of the triangle) is going to increase the height of the top of the head tube (stack, "opposite" side of the triangle) more than it pushes the top of the head tube back (part of reach, "adjacent" side of the triangle).
  • 8 2
 Get a hardtail.
  • 4 3
 170mm hardtail Lolz. "I'm and math, sciense enginerrrrrrrr so". I find the key is lots of beers, drugs, and you find the answer is BIG suspensions. Here's my thesis. "I tried to ride a bike, but the suspensions were too small." Grade A++ 105% because of bonus marks.
  • 11 1
 Did you just have a stroke? Do we need to call someone for you?
  • 1 2
 @lyfcycles: No it was a joke stroke.
  • 4 2
 Or a stroke joke. Even better.
  • 2 0
 @Kramz: moar suspensions
  • 1 0
 If anti-squat is 100% (and assuming a well-designed suspension system) then the suspension shouldn't move due to force applied to the pedals.
Since:
work = force x distance
and, power = work / time
if suspension movement is zero then work done on the suspension is zero, therefore power (watts) lost to the suspension is zero.

You could argue this doesn't really illustrate the situation for humans however since holding up a weight (zero movement, therefore, zero work) still takes energy from you. A bike isn't static though, the energy you put into the pedals has to go somewhere. Since the chain tension trying to extend the suspension is balanced by your weight moving back onto the rear suspension the forces cancel out. The energy isn't converted into heat in the damper as it would if the bike was experiencing pedal-bob and it can't just disappear so it must be going into accelerating you.

Looking at it another way you are putting the same pedaling forces into a hardtail frame and they are trying to flex the frame (just like they are trying to make your suspension move). The hardtail frame doesn't flex (much) though and the energy goes into moving you forward.
  • 1 0
 This, my MTB friends, is measuring with a micrometer and cutting with the "axe" that most MTB'ers (especially moi at age 73) ride with. :-)

Do we really think that most of us PB readers would notice such tiny differences? Especially after we haven't been riding at our "full potential" for several weeks if not months/years?

And while the old 40-years-ago "hot stove league" of discussions during the winter months in baseball was always intellectually stimulating, it was really a way to keep us hoping to generate discussion and readership. PB: take the cue!!!!!

Wouldn't a good 30-minute strength/mobility/range of motion session be more productive and beneficial? :-)
  • 2 0
 there are millions of fastners and ways to improvise, when your super stuck ask your machinest friend and quote in BEQ's (Beer Equivalent's)
  • 1 1
 "Rather than have the idea that with anti-squat a bike would be harder to pedal, let's say that the amount of energy input into the bike system is fixed, and look at where it could be lost to instead of what you really want, the bike going forwards."

So, all things being equal with the riders energy input, if you have too little antisquat, some rider energy will go into compressing the shock where some of the energy is dissipated in the damper and lost as heat.

What if you have too much antisquat? Wouldn't some of the rider's energy go into extending the shock (up from sag) where some of the energy is dissipated in the damper and lost as heat?

EDIT: A bike with too little AS might go from sag through to 100% compression due to accelarating forces. A bike with too much AS might go from sag to 0% compression. I can imagine that the damping forces and heat lost to too little AS plowing you through to 100% compression are much larger than the damping forces and heat loss that come from too much AS pogoing you from sag to 0% compression.
  • 1 1
 I'll tell ya, I rode an old nomad for a few years. On rough climbs I could feel each cobble or large root at the pedals and it sapped alot of energy over long hauls. If you like that snappy feel and your climbs are usually pretty smooth, or short and sprinty, then that suspension is for you. I like it rough and gruelling and for that a more active suspension has better traction and seems more efficient in trying to keep the bike moving at the limit of one's will when all there is, is pain. Depends on what you like. I still keep a blur around for smooth townie trails and that hard tail feel for trials moves, again, in the city.
  • 2 0
 I had the exact same experience. I went from a cheapy alloy horst link bike to a Nomad C and was blown away by how the VPP pretty much stopped working when pedalling hard over bumps. I also used that bike for training on the road, and when I started using my wife's hardtail with road tyres instead, I found that I was actually buncing the rear wheel off the ground as I sat and pedalled the HT. I think that was muscle memory from my body in some way compensating for the VPP's weird suspension characteristics under the same seated pedalling on the road.
  • 1 0
 where to find an easy software to deal with geometry changes? like : i enter the current geometry of my bike, i can see the sketch and the data. I change one parameter (like fork height) and I get the new geometry?
  • 1 0
 I’ve concluded that geometry numbers and wheel sizes are just ones opinions....I hear you, but at the end of the day I’m still riding what I started with, my 26in bike!
  • 1 0
 This site calculates the change in head angle, reach, etc with a different fork or angleset. The calculator appear to be accurate.
bikegeo.muha.cc
  • 1 0
 Maybe a bit dated but for over forking under forking go here bikegeo.muha.cc for what changes in geometry etc.
  • 1 0
 "It came from the back of a road sign of all places"
So now there's a road sign missing a bolt?
  • 1 0
 @DanRoberts what bikes were those that you’re riding with removable/adjustable idlers?
  • 1 0
 A friend had an idler made to fit inside the main pivot of an older Scott Gambler. Made it really easy to try with and without an idler and without any other changes to the bike.
  • 2 0
 All this anti squat stuff makes my head hurt and want to huck to flat.
  • 1 0
 Overforked Hell yeah . 20mm over with a 1.5deg angleset = much funnier trail bike.
  • 1 0
 Stop yelling!,
  • 1 4
 ...especially for metric bolts that are common on bikes. Most hardware stores only sell inch sizes.

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