tonski 

I use 165s on track and all road bikes, I'm 5'9" with 33" inseam. What was the +- tolerance % on the power testing?

McBTC

Yes- 6'3" and improved performance on a recumbent trainer going to shorter cranks down to 89 mm.

Baby Puke

I believe it was within the margin for error, so, negligible. It's in that article I posted, I think.

skysurfer

Yes, somebody else said it I wasn't going to. Jumping between extremes I notice negligible difference 165 to 175. But changing from 165 to 167.5 nothing, but I'm not a fussy person either so long as the drive train isn't making horrible noises I'm good.

spectastic

absolutely, according to steve hogg's website, there's a guideline where you take a person's inseam in inches and multiply by 5.48 to get the ideal crank length in mm. My 32" inseam multiplied by that puts me right at 175 or so. For you, it's more like 155 to 160. there are several of those methods, so take it with a grain of salt.

carleton

Steve Hogg has probably never been on on a velodrome. He's a road TT person.

That's like a marathon runner making shoe recommendations for 100M runners.

When you understand the demands of the different track disciplines as well as take into account the pros and cons of different crank lengths (for the same rider) and how they help one meet (or not meet) the demands of a particular event, then you will realize that there isn't an "ideal crank length" based on a person's pant size.

So, I wouldn't even take Hogg's advice with a grain of salt. I wouldn't take it at all.

My advice? Try each crank length for a significant period of time. I've raced entire seasons on 165, 167, 170, and 172.5mm cranks EACH and can tell you the pros and cons that I experienced.

spectastic

what was your personal experience?

btw. I don't race track. I race in road categories. I was just curious to get some insights on track sprinting

carleton

The short version:

- The differences are significant.
- Cranks come in 2.5mm increments for a reason, and it's not just for different femur lengths.
- Ideally, each racer should try out different crank lengths and choose for themselves.
- They should use their height or inseam length only as a starting point, not as the final word when determining their ideal crank length.

I've seen +6ft world-level racers use 165mm cranks and 5.5ft world level racers use 175mm cranks, all of whom are faster than everyone in this website...actually, everyone in the world

spectastic

if/when I get to cat 1, and perhaps get sponsorship and coaching, when this type of stuff really matters, I'll use the resources available to figure out my ideal crank length. Right now, I don't feel like 175's are holding me back at all, so I'll stick to it for now.

bitingduck

I've banged 165s on a 43 degree track on a bike with a high bottom bracket.

Banking is a very good reason. You can hit a pedal going slow, and you can also hit a pedal when you're making a sharp right on the banking (I haven't done that, but I've seen it a few times)

carleton

I get it. I mean, we all don't have sponsors or a bike room with every part in various sizes.

My point is that:

1: In their search for getting the most speed/efficiency out of their given body, all types of cyclists wonder if their crank length is "right".
2: On both extremes, sports scientists and bloggers try to answer those questions.

The thing is, there is no formulaic answer. You just have to try as many as possible for a significant amount of time and evaluate for yourself.

Other similar questions from other sports:

- "What's the best soccer boot for me?"
- "What's the best tennis racquet for me?"
- "What's the best string for my racquet?"
- "What's the best baseball glove for me?"
- "What's the best running shoe for me?"
- "What's the best golf club for me?"

And there are millions of blog posts and scientific studies and everything in-between to tell an athlete what to do.

But the bottom line is that, to find your prince, you'll have to kiss a lot of frogs.

And to be honest, man, in the bike world crank arms are pretty low on the price scale.

If you are serious about the sport, I feel that you should take time to try different crank lengths. I mean, hell, they are directly related to how fast you ride and how efficiently you do so.

Changing crank lengths could have more of an affect on your performance than changing your saddle, handlebars, stem, seatpost, brakes, shifters, groupo, chain, tires, etc...for better or worse. Yet we spend lots of money swapping those things out all the time

dunderhi

I have three track bikes which I use for different functions:

Bike 1) Schwinn for training & small gear racing - 165mm
Bike 2) Pinarello for most racing -170mm
Bike 3) Argon18 for pursuiting - 172.5mm

I've selected these lengths based upon my expected rpms:

Bike 1) 95-115rpm for training & 115-145rpm for small gear racing
Bike 2) 95-135rpm for most racing
Bike 3) 95-105rpm for pursuiting

I don't have any power data or proof that this works, but I'm happy with these choices.

P.S. My road bikes have 172.5 & 175mm cranks for 90-110rpm riding.

queerpunk

on a steep track, using the shortest commonly-recommended cranks AND having a higher-than-usual bottom bracket, you still struck a pedal. the only way to prevent pedal strike on a steep track is to pay attention.

I've never heard somebody recommend narrow shoes, shorter pedal axles, or specific pedals that are narrower in order to prevent pedal strike - but those matter to pedal strike, too.

in my other comment, i was trying to point that since using short cranks doesn't solve the issue of pedal striking (as you pointed out), it may not be the reason that many people use short cranks (nor is it the reason that some people recommend them).

SprintzNKiloz

Man this forum spiced right up when the roadies showed up didn't it?

carleton

"Yew ain't from round here...are ya? I can tell cuz ya ask funny questions. Das a-ight. Ya don't know whatcha don't know. I'll learn ya."

I welcome the discussion

bitingduck

It is (or was for a long time) the main reason many people used them and recommended them. When the Blaine velodrome was built, there was a sign (that may or may not still be there) that said (among other things) "165 mm cranks only", though many people used longer cranks there, even in the early days. And I *have* taken pedal profile into consideration for the same reason. Feet you're stuck with- you could get narrower shoes, but its probably not worth the pain, since they're flexible. Most of the biomechanics related explanations seem to arisen with the growth of the internet.

Yes, on some tracks you can tap a 165 with a high bottom bracket. That doesn't mean that that isn't the reason people use them-- longer cranks *will* hit the banking sooner, either forcing riders to ride faster or causing them to crash more. That's just geometry. I saw Harvey Nitz go down on Blaine and destroy his homemade carbon fork (in the very earliest days of carbon) because he was riding long cranks and hit a pedal on the track during warmup. There were times on that track before I had my own track bike when I was using a one of the rentals that was a road bike conversion with 170s racing against people on real track bikes with short cranks and I *was* crank length limited when we went slow.

Carson is slipperier (and was more so when it was new) and I've never seen someone with 165s hit a pedal on the track before they started to slide-- you'll always slide first there if you have short cranks. I have seen people in team pursuits with long cranks make hard right turns in the exchange and hit a pedal, and I've had a few people unwilling to ride as slow as me on the banking because of their longer cranks. Lots of pursuiters ride long cranks there, some sprinters ride shorter cranks there, and some sprinters ride long ones - it depends a lot on their racing style. There was a guy who was riding custom 190s or something like that for a while, and it was sometimes scary to watch; he didn't die, but he sure looked sketchy in sprints sometimes.

queerpunk

heh, yup, that sign is still there in the tunnel at the NSC Velodrome in Blaine. And still widely ignored. with good tires, the stall speed is very slow especially compared to Carson, but pedal strike is really really rare.

bitingduck

I wasn't sure if it would still be readable- I think it was already fading in the mid 90s.

The grain of that wood seems to make a *huge* difference in both when you'll slide and how much warning you'll get. You don't really get warning at Carson, it's just a matter of how fast you can react to avoid going down. When they were doing a lot of x-games construction in the infield and the track was closed, we had some secret sessions that weren't really open. The track had a lot of really fine sawdust on it-- not visible unless you wiped with a finger. I had hard-ish clinchers on for some reason (I usually use tubulars) and was sliding all over the place. I didn't go down, but it felt like a drifting competition.

queerpunk

i heard a pretty good story about the Shakopee Velodrome, which was around for a short bit in the 1980s, owned by Cecil Behringer - it was a six-day track that was imported and the straights lengthened, I think. They built it, had a big 3-day event planned, sponsors, audience, prize money, the works... all the riders helped build and paint it, and when they were done and they test rode it, their tires were slipping all over the place when they did anything resembling a sprint. But there was no time to repaint it - so they decided to put on small gears, consider all of the racing neutral, split the prize money evenly, and just be safe with the whole thing - and immediately after that first meet, they repainted it with a textured surface.

bitingduck

That's the first time I've ever seen pictures of it- it looks much nicer than what little I'd ever heard about it. Mostly that the transitions were done badly and were like riding over a curb, but they don't look that bad.

Baby Puke

And then they should probably use the shortest cranks they can get.

carleton

Who is "they"? The sprinter or the pursuiter?

I think it can go either way for sprinters. I think they are using both long and short cranks at the world level (depending on the rider).

I think that it's kinda settled for pursuiters to go longer.

I think mass-start guys are either going short or "whatever's on my road bike".

But, I know it's not the shortest they can get. Sarah Hammer has been reported to ride 172.5 - 175mm. Jamie Staff 165mm.

EDIT:

I started with the "5mm shorter than your road bike" rule.

Then I thought, "A little shorter that -5mm is better. Go for 7.5mm shorter than your road cranks".

Then, "As short as you can get."

Then, "Use the longest cranks that you can spin at 140+ rpm."

Now, I'm at, "Try all of the above and use the ones that help you specialize in your event(s)." because I found that using each method had subtle pros and cons. Crank length choices affected gear choices and subsequently muscle firing rates.

With shorter cranks, you lose torque, so you gear down which requires you to spin even faster to keep up. But, it's easier to spin shorter cranks...it's like running on the pedals (great for mass start racing)...and starts pulling from a different energy system than...

If you use longer cranks which give you more torque which allow you to use bigger gears and lower cadences (modern sprinting) and thus longer muscle firing rates. That means longer micro-rests between pedal strokes so you can do anaerobic work longer (modern sprinting).

There's a lot more to it than that. The bottom line is that it depends on A LOT of things (not just leg length):

- Leg length
- Rider strength
- Rider endurance
- Muscle fiber type
- Rider style (spin vs mash)
- Event type (Man 1 Team Sprint, 15K Points Race, something in-between)
- Track length (to a lesser extent)


So, it's a lot like picking the right running shoe for a runner. There are a lot of factors...most of which don't matter in the beginning, but do matter when you are winning and losing by less than a second.

Baby Puke

Carleton, you should read that article I linked to before. it's going shorter even for roadies these days, so this may apply to pursuits as well. It seems like any rider whose primary obstacle is air resistance would be better served by going shorter. But, for all of us this as academic and just a hobby, so why not experiment.

carleton

When Nothstein was racing, a world-class sprint gear was 94". Now that's a warmup gear for world-class sprinters.

But, rider weight, strength, and power are generally the same. Today's sprinters aren't any more stronger than those of the 90s. What changed are the sprinting styles (in my opinion). In the 90s, the sprints started with around 250M to go (at the bell).


Now, it seems that sprints generally start 375-400M out. Watch in both of these how they are fully committed at around 400M:


Yes, the big gear does require more time and distance to wind up. But, you have to ask,

When Kenny beat Bauge in 2012 Olympics, the 200M splits were 10.2", 10.3"

When Fiedler beat Nothstein in the 96 Olympics the final 200M splits were 10.6", 11.0"


But, "2012 athletes are faster than 1996 athletes...duh." Not really.

Here are the qualifying times for the 1996 and 2012 Flying 200s.

Fiedler's 10.232" F200 would have qualified him 12th in the 2012 Olympics! He would have made the tournament! But...he would have gotten his doors blown off if his final sprints in comp were 10.6 and 11.0 (after a long tournament of racing). Notice how Kenny and Bauge (also after a long tournament of racing) are clocking low 10s in the final flying 200M in the finals. I think this probably has more to do with using bigger gears than fitness or raw speed. Maybe the bigger gears are less taxing throughout a tournament and/or the long sprints with the big windup will simply beat riders on smaller gears every time.

Baby Puke

Bigger gear does not necessarily mean longer cranks. No one is debating that folks ride bigger gears these days.