I’m pretty satisfied with my TT position but would like to go to shorter cranks to open up my hip angle since I’m riding with a good deal of drop and have a flat back (0 deg). Currently riding with 175mm cranks (56cm P3). Is there a rule of thumb like at least 5mm less?
There isn’t really any algorithm for it. Are your hips actually bothering you? Do you make less power in aero than you do on a road bike?
If not, you don’t need to change anything.
Otherwise, if you are going to experiment, you might start with small changes and see if anything improves.
Not picking on you but I just don’t see how 5mm can make anyone’s fit any different than dropping their heal 5mm. (which in my opinion a very small movement)
jaretj
I don’t think there’s a rule of thumb, but I doubt you’ll notice much different with just 5mm less. Better to go to 170’s or 167.5mm.
That being said, If you have Shimano 10 speed, I could sell you my old 172.5 mm cranks pretty cheap. I went to 165mm and am very happy with the change. I thought about putting them on my road bike some day and upgrading it to 10 speed. But I have a feeling it won’t happen anytime soon.
Keep in mind that when you go with shorter cranks you have to lower your seat by the same amount, so you’ll lose some effective drop on the front end. So you might plan on removing a spacer, or going with an different stem at the same time.
Honestly since TT’s and Tri’s in particular are about sustained power not sprinting or accelerating or climbing hard out of the saddle, I don’t think there’s much risk or negatives with going short, and plenty of benefit to opening your hip angle. There’s plenty of average height riders going down to even 160 or 155mm.
You can get Shimano 105 10 speed 165mm crank for like $140-150. That’s a pretty cheap experiment, since you could resell them for at least $100-120 at least.
Keep in mind that when you go with shorter cranks you have to lower your seat by the same amount, so you’ll lose some effective drop on the front end. So you might plan on removing a spacer, or going with an different stem at the same time.
Actually you need to raise your saddle with shorter cranks rather than lower it so your drop is even greater.
Hugh
Thank you, that’s what i thought (raise your saddle by the corresponding length change in smaller crankarms).
Well there is the peer pressure of ST - everyone is going to smaller cranks. But my hips feel like then are pinching when at top dead center and my run is pretty sucky for the first 1/2 mile (I only do sprints, Olys and TTs due to my crappy swim). I dont have a power meter on my P3 (blasphemy I know). Here’s a picture of my position although the camera angle is not very good and I have my eyes closed : ).
that does look pretty pinched, and you are getting some quad-stomach interaction =)
Give 170s a try. OR, perhaps moving the saddle forward if your effective seat tube angle is shallow (it doesn’t look like it is, given that I think I see an adamo, in the forward seat hole)
Well there is the peer pressure of ST - everyone is going to smaller cranks. But my hips feel like then are pinching when at top dead center and my run is pretty sucky for the first 1/2 mile (I only do sprints, Olys and TTs due to my crappy swim). I dont have a power meter on my P3 (blasphemy I know). Here’s a picture of my position although the camera angle is not very good and I have my eyes closed : ).
Yea that’s a pretty acute hip angle.
This was mine before I switched to 165’s from 172.5’s. I am really happy about the way it feels now (hip angle wise) and power production seems to have increased in the aero position.
The quad / stomach interaction is mostly belly breathing (exhale) plus a loose fitting kit plus camera angle = ) (I’m not a fatty =)
Yes its an Adamo in the forward hole. Seat is pretty far forward although I do have a long torso so I dont like being way over the front end. I’m leaning towards a 165mm Rotor aero crankset. Thanks for the replies.
I went from 170s to 150s and have a set of 145s I will try. I used Bikesmith who cut the arms and it was an inexpensive experiment other than my Quarq was no longer useable. I did have some hip issues due to other health issues but it was at the point I was unable to ride on any incline. It was amazing how different I felt on my bike and hip opening up was more significant than I expected. I did get another fit by Todd Kenyon at TTbike.com with the change.
I would suggest considering going bigger change than 175 to 167.5 to see if it helps with position and hip angle.
I’d suggest getting a fit with new cranks.
Go Bay State!
I dropped 22mm from my TT crank length. It wasn’t hard to get used to… and I mostly ride the road bike which has long cranks. I don’t see a lot of point unless you make it a significant change.
The cheap way to try short is to run BMX cranks… though if you have a non-standard (BSA) BB that might not work.
Keep in mind that when you go with shorter cranks you have to lower your seat by the same amount, so you’ll lose some effective drop on the front end. So you might plan on removing a spacer, or going with an different stem at the same time.
Actually you need to raise your saddle with shorter cranks rather than lower it so your drop is even greater.
Hugh
Woops sorry, mixed that one up. I’m blaming it on running withdrawal… 10 days without running for that 5 minutes straight.
Kudos for the stickerless wheels. OK, back to the topic at hand.