I’m 5’9ish and really like my 51cm P3c. I’d always had a 175mm crank on the bike, and decided to see what a shorter crank would be like. I’d read that I could raise the saddle, get a bit lower (drop), and my knee clearance to my torso would be better. Since I’m already on a pretty small bike, and feeling like I could use more knee clearance, I figured the shorter crank would be a good fit.
So on Sunday, I installed the new Redtegra 6600 165mm FrankenCrank:
I’ve been riding my road bike since December, so I haven’t been riding this bike, or aero for at least 3 months. Also, the road bike has 172.5mm cranks, so in actuality I went from 175 on the TT bike to 172.5 on the road bike, and now to 165mm on the TT bike. Probably not the best scenario for subjective testing, but whatever. Here is what I’ve observed after 4 rides.
My power output is somewhere around 10 watts less at the same RPE when sitting up (which is the position I’m most used to right now).Because of this, my cadence has gone up to accommodate wattage targets. Not sure if this is a positive or negative.Power when riding aero is about the same, maybe a little less since I’ve been riding upright roadie style lately.At first I totally forgot I had shorter cranks until about 4-5 minutes when I looked down. It’s not instantly noticeable.
Climbing is way different with shorter cranks. Way different.I seem to get a lot more clearance between my knees and belly. Maybe my elbows too?Overall I like having a shorter crank than 175s, but I think for me, 165 is a little too short. I’m going to give it some more time, but I’d be interested in hearing others’ experiences going shorter. I might eventually look to make a trade for 170’s.
I went from 172.5 to 165. I liked them for flat courses but for climbing, not at all. And the overall impression was that it just seemed like too much spinning to me and I’m a high-cadence kind of guy already. But I might try again, just to be sure, next season.
In the end, I backed off to 170 (kind of copying a friend who did it as well) and that seems to have been the right choice.
Edited to note that I am 6’ 0" tall and use a compact crank on all my bikes, if it matters
I’m 5’9" too, and went to 165s midway through last season… At first, I definitely noticed them on the hills too. But after a while, I just got used to it - after longer rides, my knees did feel better on the shorter cranks, and I was overall much more comfortable in aero. I don’t have any power toys (gasp!), so I can’t comment on wattage won or lost. Yep, cadence had to come up and some other tweaks, but I just get used to it over time.
Every now & then, I consider swapping back to my 172.5s or trying a 170, but I’m just too damn lazy to switch. Meh. I’m comfortable now, so why mess with it…
The more I think about this crank-length brouhaha, the more it’s like the never-ending “what type of shoe is better?” debates - just pick something comfortable that works for you, and roll with it!
I’m 5’5"…I went from 170mm to 165mm. Lots of formulas and calculators say I should go even shorter…between 152mm and 162mm, depending on the formula/calculator. But, it’s not easy to get cranks that short so I went with SRAM Red 165’s.
5mm shorter…I basically did not notice any difference at first. Didn’t feel different…didn’t notice the slight saddle raise, didn’t notice the extra clearance between my knee and torso…didn’t notice the slightly more aero position. Everything felt the same. But…then I got to a hill…and the hill I usually go up felt a bit harder to get up. Feeling remained through repeated trips around this particular loop. Then I loaded up all my Garmin data…and my top speed and average speed for the loop had gone down.
I think maybe I’m not spinning any faster…I’m pretty sure I have to work on my cadence.
5’10" here, and went from 175 to 165 on tri bike. Not sure why you care what the sitting up position nets you, as that is not how you ride a tri bike. I love how my hip angle is opened up, and I feel a lot less stress there on on my knees. No power toys here, just a million miles of riding those 175’s waaay too long. I have not noticed any reduction in speed, and I can stay aero longer and more comfortable. I went to FSA compacts for my switch, and probably will go down even further once I can get similar cranks in 160 to 155. I also have short legs for my height, which is also a consideration, built for swimming…
5’10" here, and went from 175 to 165 on tri bike. Not sure why you care what the sitting up position nets you, as that is not how you ride a tri bike. I love how my hip angle is opened up, and I feel a lot less stress there on on my knees. No power toys here, just a million miles of riding those 175’s waaay too long. I have not noticed any reduction in speed, and I can stay aero longer and more comfortable. I went to FSA compacts for my switch, and probably will go down even further once I can get similar cranks in 160 to 155. I also have short legs for my height, which is also a consideration, built for swimming…
hey monty, thanks for your feedback. Sitting up is definitely not how I’m supposed to ride this bike. However, I’ve been riding the road bike for 3 months, so I wanted the comparison to be as equal as possible. (I’m also working my way back down slowly.) Since I seem to be losing some power, I wanted to be sure the variable that changed was the crank, and not my riding position. Of course this is a different bike, and my test is not perfect. I’m glad to hear you’re built similarly, and like the shorter cranks. It gives me a bode of confidence to keep pressing forward.
Climbing is way different with shorter cranks. Way different.Did you put on lower gearing at the same time? If not, then you’re basically climbing in a “bigger gear” than you were before…
Climbing is way different with shorter cranks. Way different.Did you put on lower gearing at the same time? If not, then you’re basically climbing in a “bigger gear” than you were before…
Same cassette and matching 53/39 rings. Same wheelset.
Climbing is way different with shorter cranks. Way different.Did you put on lower gearing at the same time? If not, then you’re basically climbing in a “bigger gear” than you were before…
Same cassette and matching 53/39 rings. Same wheelset.
There you go…you changed the “gain” between your pedal and the road. You need lower gearing.
I went to 165’s and compact cranks. I’ve got some odd issue that when I put heavy load on my hamstrings (like a weighted squat or hard intervals), my biceps femoris starts rubbing/clicking on my fibula head. First ride outside was different, but good. I’ve done a few CT rides over 2 hours and my legs feel amazing now. I wouldn’t have survived the 172.5’s 53/39 I was riding any more.
Crank length is part of the “gearing system.” You shorten your lever arm for applying tension to the chain, and in order to keep the same mechanical advantage (ie gear ration) you need a longer lever arm at the rear wheel (ie a bigger cog).
Tom A and jpb are correct - in my earlier post, I should’ve mentioned that I lowered my gears accordingly to account for the shorter cranks. That is definitely important to consider. I suppose I adjusted my cockpit too, but that was due more to slapping on a new saddle around that same time. If all you change in the go-go equation is crank length alone, it’s likely going to be a disappointing experience.
When I made the switch, I wasn’t concerned about losing speed or power, and I didn’t have any illusions about seeing any dramatic gains there (immediate or long-term). For me, it was all about trying to get more comfortable while in aero and a bit of knee relief. And that has worked out nicely.
does this account for any imaginary gain from having a better lever arm applying the force to the cranks? ie, when sitting upright, i lose power as i slide back in the saddle(hip angle factor minimum) i have more power climbing from sliding to the front of the saddle(nose) i have proportionately short femurs(hip angle in aero)
i said imaginary as i have not tested it “rigorously”
i have a nice climbing TT late May to see how they climb
It’s not so much that I run out of gears, as I realize 39/23 with 165mm cranks will be more difficult than it was with 175mm cranks. From my very limited experience on 165’s, it seems like since the lever is shorter, I get less oomph when I stand up and mash down. The shorter arms seem to want me to spin, rather than grind.
