I recently did a wholesale swap of my tri and road bikes. I put a 175 crank on my road bike. I had a 172.5 on my last bike and sold it rather quickly because of that and a couple of other issues I had with it. My new tri bike came this week and it has 172.5 cranks on it, when I thought it had 175s. My initial thought is that it's a bad choice to have two differing crank lengths. I had it before with tri being 175 and road being 172.5, and hated the feel of the 172.5 whenever I got on the road bike, but I'm wondering if it will be that noticeable on a tri bike. I am going to make the decision on cranks before I ride it just so I can sell the crank new if I decide to swap, but thought I'd see if anyone has any experience with this to help me make a decision. I know there are advantages to shorter cranks on a tri bike, but not sure if the negatives of two crank sizes outweighs that. Any thoughts are appreciated, thanks.
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Re: Different crank lengths between bikes [ko21]
[ In reply to ]
First, several folks have different crank lengths on different bikes. I don't know why it'd be a negative. It's a big positive for me.
2nd, I wonder if Q factor (width), geometry, or fit, and not crank length, was the issue with your last setup.
And finally, if you can tell a 2.5 mm difference, then you're more attuned/sensitive than most. i wouldn't personally change cranks for that, but why not slap it on a trainer and see?
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2nd, I wonder if Q factor (width), geometry, or fit, and not crank length, was the issue with your last setup.
And finally, if you can tell a 2.5 mm difference, then you're more attuned/sensitive than most. i wouldn't personally change cranks for that, but why not slap it on a trainer and see?
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Life is tough. But it's tougher when you're stupid. -John Wayne
Re: Different crank lengths between bikes [ko21]
[ In reply to ]
Most people can't feel a 5mm difference.
Re: Different crank lengths between bikes [ko21]
[ In reply to ]
I've got:
172.5mm on CX bike
175 on road and mtb
165 on tri.
No issues. Go with the best fit.
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Any run that doesn't include pooping in someone's front yard is a win.
172.5mm on CX bike
175 on road and mtb
165 on tri.
No issues. Go with the best fit.
------------------------------------------------------------
Any run that doesn't include pooping in someone's front yard is a win.
Re: Different crank lengths between bikes [ko21]
[ In reply to ]
I haven't noticed any issues between my disparate crank lengths:
170mm Road bike
170mm Mtn Bike
155mm TT bike
and I ride at least 2 of the 3 every week. Each bike has differing positions, and the crank lengths reflect those positional differences.
I personally don't feel a 2.5mm difference when I happily ride a 15mm difference (TT to road or Mtn) on back to back days all the time.
170mm Road bike
170mm Mtn Bike
155mm TT bike
and I ride at least 2 of the 3 every week. Each bike has differing positions, and the crank lengths reflect those positional differences.
I personally don't feel a 2.5mm difference when I happily ride a 15mm difference (TT to road or Mtn) on back to back days all the time.
Re: Different crank lengths between bikes [ko21]
[ In reply to ]
It's quite typical for a TT/Tri bike to have shorter cranks than a road bike for the same sized rider. I have 175's on my road bike, and 170's on my tri bike. I've never "felt" anything strange going back and forth between the two. If anything, I feel like I could go shorter on the tri bike.
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Re: Different crank lengths between bikes [gary p]
[ In reply to ]
gary p wrote:
It's quite typical for a TT/Tri bike to have shorter cranks than a road bike for the same sized rider. I have 175's on my road bike, and 170's on my tri bike. .I have the same set up.
I have knee cartilage problems. Because of accelerations and hard pulls, the road bike sees a lot more watts than the tri bike. The longer cranks on the road bike, so my theory goes, reduces the pressure on the cartilage during those peak efforts. For example, I pretty much have to stay in the saddle. If I get out of the saddle to climb, I'll pay for it later.
I don't like 175s on the tri bike tho. Makes it harder to get low.
Neither feels foreign. I greet both like an old friend.
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Last edited by:
RangerGress: Jun 5, 17 5:42
Re: Different crank lengths between bikes [ko21]
[ In reply to ]
Thanks for the replies. I didn't like the fit on either bike before, so that may have been more the issue. I am not super sensitive to small variances and didn't think I would feel a difference between the crank lengths, so there must have been other factors at play with those bikes. I'll just go with the shorter cranks on the TT bike, that makes it a whole lot easier.
Re: Different crank lengths between bikes [ko21]
[ In reply to ]
I have 170s on my roadie and 165s on my TT bike and I honestly cant tell the difference between the two bikes! if you set them up properly there shouldn't be much of a issue except maybe the slightest difference in cadence but im talking about 1-3 revs higher so marginal difference.
recently I have been almost matching my TT cadence avg on my roadie so I am either better suited for 170s or 165s tire me out/overspin.
Speed kills unless you have speed skills!!!
recently I have been almost matching my TT cadence avg on my roadie so I am either better suited for 170s or 165s tire me out/overspin.
Speed kills unless you have speed skills!!!
Re: Different crank lengths between bikes [ko21]
[ In reply to ]
Sometimes I run different crank lengths on the same bike at the same time. I have a 170mm stages arm that I sometimes like to use on a a couple bikes that have 175mm cranks. I cant tell the difference between having two different crank arm lengths on one bike at the same time, let alone having different lengths between bikes.
Re: Different crank lengths between bikes [jimatbeyond]
[ In reply to ]
jimatbeyond wrote:
Most people can't feel a 5mm difference.A couple of things:
- They can't feel the difference, but they will subconsciously change their cadence for the same power/perceived effort
- If you put them on 2 bike with identical fit coordinates for downstroke and hip angle and make them switch back and forth, they will probably tell you there is something different, but they still won't likely know what it was.
Re: Different crank lengths between bikes [ko21]
[ In reply to ]
ko21 wrote:
I recently did a wholesale swap of my tri and road bikes. I put a 175 crank on my road bike. I had a 172.5 on my last bike and sold it rather quickly because of that and a couple of other issues I had with it. My new tri bike came this week and it has 172.5 cranks on it, when I thought it had 175s. My initial thought is that it's a bad choice to have two differing crank lengths. I had it before with tri being 175 and road being 172.5, and hated the feel of the 172.5 whenever I got on the road bike, but I'm wondering if it will be that noticeable on a tri bike. I am going to make the decision on cranks before I ride it just so I can sell the crank new if I decide to swap, but thought I'd see if anyone has any experience with this to help me make a decision. I know there are advantages to shorter cranks on a tri bike, but not sure if the negatives of two crank sizes outweighs that. Any thoughts are appreciated, thanks.I train on 172.5 and race on 165mm I feel huge difference.
Re: Different crank lengths between bikes [sebo2000]
[ In reply to ]
sebo2000 wrote:
ko21 wrote:
I recently did a wholesale swap of my tri and road bikes. I put a 175 crank on my road bike. I had a 172.5 on my last bike and sold it rather quickly because of that and a couple of other issues I had with it. My new tri bike came this week and it has 172.5 cranks on it, when I thought it had 175s. My initial thought is that it's a bad choice to have two differing crank lengths. I had it before with tri being 175 and road being 172.5, and hated the feel of the 172.5 whenever I got on the road bike, but I'm wondering if it will be that noticeable on a tri bike. I am going to make the decision on cranks before I ride it just so I can sell the crank new if I decide to swap, but thought I'd see if anyone has any experience with this to help me make a decision. I know there are advantages to shorter cranks on a tri bike, but not sure if the negatives of two crank sizes outweighs that. Any thoughts are appreciated, thanks.I train on 172.5 and race on 165mm I feel huge difference.
This post you made does not give us enough colour. The huge difference is it in power output generation? Or is it in comfort at the same power levels, and is this applicable both sitting up and in the drops or in the aero (which leads to another question, what type of a bike are we talking about)....and the final question would be around your body size...are you 5 feet tall with a 26 inch inseam, 5 feet tall with a 38 inch inseam, or a 6feet 6 with a 27 inch inseam, or 6 feet 6 wtih a 38 inch inseam (picked some extreme examples there but hopefully you can get that some more specifics would be useful).
I'm about 5'9''-5'10'', 71kg (161-ish lbs), and 33in inseam (longish legs). Riding a 172.5 on road bike (Specialized tarmac) and 165 on tri bike (speed concept gen 2).
I do notice a pretty big difference on cadence, but power output seems similar. The 165's spin up easier and I'm probably around 95 rpm most of the time. It feels easier to keep a consistent power output throughout the pedal stroke when I'm in the tri bars. Also, it seems easier to stay in aero position at higher power outputs (at least indoors).
On the road bike, I usually spin lower depending on the course, but noticed I am usually spinning lower most of the time. If I'm in a pack of riders, I noticed I spin higher b/c I'm trying to keep up and take the front (on occasion).
No issues with legs, etc... so far. I was on 170's on the SC until earlier this year, will see how the 165's work through an IM in August! :) Bike fitter said I made the "right decision" with the crank length...who knows!
Sorry, can't see a pic...tinypic doesn't seem to work!
I do notice a pretty big difference on cadence, but power output seems similar. The 165's spin up easier and I'm probably around 95 rpm most of the time. It feels easier to keep a consistent power output throughout the pedal stroke when I'm in the tri bars. Also, it seems easier to stay in aero position at higher power outputs (at least indoors).
On the road bike, I usually spin lower depending on the course, but noticed I am usually spinning lower most of the time. If I'm in a pack of riders, I noticed I spin higher b/c I'm trying to keep up and take the front (on occasion).
No issues with legs, etc... so far. I was on 170's on the SC until earlier this year, will see how the 165's work through an IM in August! :) Bike fitter said I made the "right decision" with the crank length...who knows!
Sorry, can't see a pic...tinypic doesn't seem to work!
Last edited by:
tri@thlete: Jun 5, 17 9:34