Going to 165 from 175mm Cranks + Bike Fit

I just got back from beautiful sunshine in Crete… Wow… Nice… Missed my gravel race because of it but had so much fun with the family it was more than worth it.

In most cases I agree with you Dave although I do know it is possible to get your protocol so tight with MAF/AeT tests that you could differentiate between these. 1% drift and basically 0% are actually a noticeable difference in drift. So if you know your protocol is extremely consistent (which it can be with an AeT test) then it does mean you lost a little, but that would surprise me in this case.

But still I agree with everyones comments these are very good results and can easily (for most people) mean nothing negative as Dave pointed out.

I need to get back to consistent cycling after vacation. My motivation his very high. On vacation ChatGPT helped convince me I need 165mm cranks :slight_smile: so have them showing up on Monday. I am 188cm tall so this is on the short side but the reason is comfort and health/safety not performance (sounds good right?).

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Nice Results, Blacktek. It shows that time away from the bike, doing different training, can keep good form.

@Alex: Has ChatGPT also told you about the totally different bike position with shorter cranks? The reason why most pros choose shorter cranks is that the total position on the bike changes to a more aggressive one.

My position is already quite aggressive for an amateur of my age, so I’m still not convinced. On the other hand, I have never been the early adopter type.

What reasons did ChatGPT give you that changed your mind?

The core idea is as we age we lose mobility. Now if you are consistent enough or doing enough mobility stuff you can slow that down obviously but regardless it will eventually happen. So for you at your age the value might be much lower than it is for me and my mobility at my age. The biggest take away that I see is more that their are not many down sides to going shorter. Obviously in MTB or hard very short sprints their can be but this is not my concern.

I have hamstring soreness on 80-100km rides (I just need to stand every 10 minutes for a bit or stretch it out to make it acceptable) and tried lots of different positional stuff. Generally GPT feels the agreement is that shorter cranks will reduce the amount of extension required and very likely to help.

Here are a couple comments from GPT for example.

Improved circulation: Less compression at the top of the stroke can improve blood flow, particularly helpful for older or heavier riders.

Reduced joint strain: Shorter cranks decrease the hip and knee flexion angle at the top of the pedal stroke, helping:

  • Those with hip impingement or arthritis
  • Riders with limited hamstring or lower back flexibility

Lower risk of pedal strikes: Useful on gravel bikes or during cornering.

So again this is more for me and my specifics than a general improvement for all. My guess is for you the cost vs value is not worth it at this time. I doubt you will get any noticeable benefit unless you have specific issues you are trying to resolve. If you regularly ride around at 50kph then you might get some aero benefits :slight_smile:

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So the more aggressive benefits pros are using it for means more aero, theoretically the same level of negative implications on your body, but again this has nothing to do with my reasons. It is possible you could keep the same aggressive/aero posture and reduce strains/discomforts… but I have no idea it if makes sense for you. I think it’s mostly just for problem solving, not performance for most of us.

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I’m very curious about your findings. Please keep me posted.

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I have 172.5 on road bike (were actually 170 originally, but replacement by warranty only had longer ones left on stock) and 165 on gravel. I feel no difference at all. Had to adjust saddle height though, but that’s expected.

Cool, yes I don’t think I will notice either other than moving the seat up which will cause me to be more bent over, soon I need to get those redshift riser bars :slight_smile: I think unless you are regularly riding a gravel bike with big uphill single track then 165 makes total sense to me. Overall in my case I am just trying to solve a specific hamstring problem other than that I would stay with 175. I am adding spindle power meter which is essentially dual sided which is cool. I use spacers to widen my pedals (could say bigger Q-factor even though technically that is the wrong term in this case) so that seems to throw off my single sided pedal power… So hopefully solving 2 problems at once.

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You will only feel difference if you are in very aggressive aero position (low torso) and/or have a hip flexibility problem.
Shorter cranks allow you to raise your seat and if you raise your bars the same amount (as it should), your torso is in the same angle. That creates more room in between your upper leg and your torso because your upper leg rises less with the shorter cranks.
If you have no problem with hip flexibility and already ride a fairly aero position, there’s no reason to get shorter cranks. It’s once again one of those ‘hypes’ but it can help people who have to adopt a very upright position because of hip problems.

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Exactly. I agree completely. It might give 0.5% to pros (including slightly more aerodynamic leg length which might be measurable at 50kph+) but for me it’s just the hip flexibility problem. I am not very aero now and still believe this might improve my issue.

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Raising bars, tilting brake levers a bit and slightly put your seat a bit more forward can help to free-up more room in the hip sector. If that’s not enough, get shorter cranks, but that is normally only needed on road bikes. MTB should have more then enough room to play with, unless the sizing is completely off.
165 iso 175 on a road bike will also massively improve hip function. If bars are raised with the seat, you get 20mm more space which is huge.

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Yes, I did all that and many more tests but still have hamstring pain/tightness that does not seem to be related to muscle utilization. I also believe their is a small chance it’s “healthier” or slightly safer to have shorter cranks but that’s based on theory that is likely un-verifiable.

It’s interesting that lowering seat reduces the stretching of your hamstrings but also increases the reliance on them to turning the pedals… I am not super optimistic that 165 will magically fix my issue but it’s worth the test for me. Really it’s not so bad unless I want to do 150k+ days. But I prefer to feel “perfect,” rather than having moments of slight amounts of discomfort for brief periods if it’s possible.

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Do you have a huge increase in hrs / Km this year? If I recall you weren’t riding much before.

How has the ramp up to 150 Km gone?

I’m much more interested in athletic development than crank size :slight_smile:

Dave

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:slight_smile: My wife scheduled vacation for last 2 weeks when the 150km race was so I had to miss it. It was not great weather and I would have been suffering. I did do like 105km prep ride… Funny after 2 weeks away from the bike and today first day back it feels like I am starting over.

Yes for sure I was not riding much and progressed to 100km rides in 2 months and 10+ hour weeks end of last season and again the same this season. I am really very zone 2 focused for now until I have a base and solve my comfort issues.

For sure training is much more relevant to this group and more fun in general but while I believe my comfort issues might only be volume increase related to me it feels like I can keep working on improving bike fit myself (not convinced on single Retul provider here, will wait until I am desperate) and improve this faster than just waiting for my body to catch up. In my bike fit discussions with experts and chatGPT, and research in general I just realize that the standard advice I see is not very accurate or beneficial at least for me.

There is 180km gravel race here in a month but I have decided I need to get more comfortable on 100km before I tackle anything longer. Sept is another 150km so that would be the target unless I can resolve all my comfort issues sooner.

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I can say I just love riding bikes right now… So fun just to be out there. I feel like where I live is so perfect for those lonely paved roads with a bit of gravel and single connecting them.

I am also very excited about (minimalist) weight training, but even though I always tend to do a bit of something every time I get back into something more seriously I feel I need to go through a longer base phase to be safe. So base phase of weight training as well.

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We could just start a new topic for both of us to provide updates :slight_smile: We both have similar goals get comfortable and minimal recovery after 100km rides… And a bit more speed/power with that as well.

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Were you a long distance guy from years back or is this new for you? I’m impressed with your progress!

Dave

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We’ve really embraced just going slower this year, stop and smell the flowers and that kind of stuff. I ride mostly with my wife. I’m stronger so I always pull and she can draft.

We went on a road route on Sunday with a lot of rollers, but they aren’t steep. We tried to set a target of 130 bpm and I ended up at 132 bpm versus a max of 190 so just under 70%. We went about 42 miles in just slightly over 3 hours, avg speed was 13.8, but I’m not trying to impress anyone.

She did great finishing with 132 bpm also.

We had a ton of fun and felt great after the ride.

I used to have a never less than 15 mph avg speed fixation and 50+ mile rides over hillier terrain would leave me very tired.

Dave

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I did my first 2 day back to back US Centuries when I was 15… I used to ride BMX for 20-30km :slight_smile: semi-regularly. But my real ultra stuff was 15-28 hour days mountain climbing… I did a lot of long days in the mounts Some long snowshoe days… I ran R2R grand canyon once (well run / walk on the way up)… It was 105F at the bottom and we were running around down there… Did a marathon once… did a lot of 50km days on bike both MTB and “road” and a few other 100 milers but never raced anything and never highly consistent multiple times per week at any single sport for more than a year or two… but always have been doing something other than brief breaks or transitions from one sport to another. I was a surfer in Hawaii for 2 years… I have a long list :slight_smile:

That sounds great!!! I love it. Even Andrea thinks pros should take this approach a little more.

As you are aware, I like to put fun at the front of any training, so when going hard is fun I do it, you often get to points where it is super fun but when it stops aligning with my life goals then I back off and just have fun. I am not saying just because one day a specific workout is not super exciting to skip it, I am just saying overall align your goals with your training.

I have slowly grown to realize that consistency is the only thing that matters (besides fun/pleasure)… So until you can master that no reason to work on anything else unless it is fun. Following specific training plans and workouts can be super fun and add to consistency as well so it’s great. The obsession of data can be motivational.

Ok first 1 hour ride with 165mm and I can say it seems like my hamstring pain/irritation… is gone. This is exciting if so… Also I can feel the difference in how the torque / length feel but really makes no difference and I won’t notice it at all very soon.

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