Getting ready to start my third tri season I decided it was time to upgrade to a tri bike. Still feeling very much a novice, I took the advice so often given here and got a pre-purchase fitting. He gave me all my measurements and a list of recommended bikes in my price range. Of the many measurements he gave me, one he said was important was that the crank should be less than or equal to 170.
As fate would have it I found a great deal on a new 2011 Felt S22 which was both my top choice and the top recommendation of the fitter. The only problem is that it currently has a 172.5 crank not 170. How big a deal/difference is 2.5 mm? Everything else on this bike is perfect.
Honestly, you would probably never notice any difference. Besides, depending on what crank you are talking about, you might be able to pick up a set of arms (or a whole new crank) for pretty cheap and just swap it out. But honestly, going from 172.5 to 170 won’t change much…going from 175 to 165 is a different story.
You need to make sure the new cranks are compatible w/ the existing BB first. After that, whether or not it comes w/ rings (a full ‘crankset’) or if you want to swap over the chainrings you already have, then you need to match the bolt circle (standard vs compact); a 52-38 could be either.
Depends on your inseam length, but more on the way you pedal. If you normally push big gears, I would go with 170, if pedal with high cadence, I would go with 172.5
It will have a noticeable impact on comfort & efficiency depending on your fit; specifically if you want to have an aggressive position. Crank length is a hotly debated topic but the bottom line is that it does not affect power. It’s just another fitting tool to get you in the most aero/efficient position possible. There are plenty of studies that prove this and I can email them if you like. So as mentioned, it all depends on what you want to get out of YOUR particular position (your frame, flexibility, race distance, etc).
backwards and also begging the question on leg length and pedaling “style”. Both red herrings, a logical fallacy.
crank length should depend mostly on power output, especially triathletes, where running shorter cranks has ancillary benefits of helping with aero position and for me, helping to feel fresher when running off the bike. A corollary to that is the longer the race, the shorter cranks you should run.
If you’re a 300 watt guy for a half IM, sure by all means run 175s if you’re tall or 172.5s if you’re not. For the rest of us, consider shorter cranks. Look at Craig Alexander… running 167.5s, spinning at a high RPM, running very well off the bike.
Depends on your inseam length, but more on the way you pedal. If you normally push big gears, I would go with 170, if pedal with high cadence, I would go with 172.5
I think this is the wrong way around? Big Gears = slower cadence = longer cranks. Small gears = higher cadence = shorter cranks.
I’m w/ earthling here… If you’re a ‘masher’ then a longer lever is good for extra mashing force; whereas for a spinner, it’s easier to spin more fluidly in a smaller circle than a larger one at higher cadences. Think no further than MTBs, where 175s are standard for grinding up steeps, vs Track, where 165-167.5 is normal for even big dudes who have to ramp up to sick RPMs since you can’t pick too big a gear to start out with.
No, I’m a TT specialist and I have moved down from 172.5 to 170 just to get my revs up because I push big gears. That is an old euro thing to go with longer cranks for TT just like everyone rode 55 and 56cm frames if you were 5’10" and the saddle was on the top tube. All of the research leads to the fact there is no benefit to longer cranks. It comes into play with fore/aft/foot placement on the bike if you have weird body part lengths. The crank arm is not a static lever.