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I have a 50-32 crankset (165mm Crank arm length) and an 11-32 cassette. I'm having difficulty when I switch up to the 50. I do Sprint Triathlons as an age grouper (70-75).

Additional information: I am 70 years old, 5' 4" tall, and training for Sprint Triathlons. My goal is to be able to ride the highest watts I can (current FTP is 114 W) without too much knee pain. I have osteoarthritis, particularly in my right knee. I qualified for USTA Sprint Nationals for the first time this year and will hopefully be invited to the 2024 race. I am still learning to ride my TT bike, so I’m doing most of my training on a Tacx trainer indoors.

Your thoughts and suggestions are most welcome.

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    Welcome to the site - what is the difficulty you're having? Chain drops? Hard to get the chain up to the 50T chainring? Lack of power? Low crank RPMs? Knee pain?
    – Criggie
    Commented Dec 3, 2023 at 8:18
  • Welcome to Bicycles SE. as Criggie mentioned, some additional information is needed for the group here to work with. Please edit your question to add the pertinent details, and in this case the more detailed, the better.
    – Ted Hohl
    Commented Dec 3, 2023 at 12:52
  • These are issues for me: Lack of power? Low crank RPMs? Knee pain Commented Dec 4, 2023 at 1:24
  • Can you describe the issue in your riding and what the problems are that you are facing, respectively what kind of solution you are expecting? I don't want to be disrespectful, so we need more information to give constructive advice because we can't assess your current health and training status and I really don't want to be pretentious.
    – DoNuT
    Commented Dec 4, 2023 at 10:05
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    From what I can gather over the internet, osteoarthritis is no contraindication for cycling, at least recreational cycling is recommended as exercise, as well as swimming... Not sure on running. Consult a doctor - not being able to push hard gears on the big ring, with potentially pretty easy combinations on a compact crank with relatively wide range is something that shouldn't be tackled by internet advice.
    – DoNuT
    Commented Dec 5, 2023 at 7:42

1 Answer 1

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This is one of those questions where, no matter how specific you get, you are best served seeing a professional in person. The issues are still too vaguely described to offer specific advice.

I outlined some of my thinking in this answer. Briefly, I am not sure how much a medical doctor would help. Now, that said, the medical discipline physiatry deals with all issues related to physical medicine and rehabilitation, so if you see an MD it should definitely be a physiatrist. If you had something like a joint replacement or serious orthopedic injury, you should often get referred to one of these folks after the acute phase. They will often work with physical therapists. You can often go to a physical therapist directly, your insurance arrangements permitting (this includes your national insurance's policies, if you're in a country that uses that). I suspect many people don't know this, but this is a potentially productive route.

Most physical therapists won't have sport-specific training. So, they may miss some stuff related to how your bicycle fits you. That said, knee pain can stem from or be aggravated by muscular imbalance issues. PTs definitely can help you determine which muscles to train or stretch.

Bike fitters are not licensed like MDs and PTs. (Mostly not, but you may encounter occasional fitters who also have PT licenses.) They deal with how your bike fits you. Moreover, good bike fitters also know how to assess your flexibility and range of motion, and they too can recommend stretches and strengthening exercises. I'm not sure how common this type of crossover knowledge is among fitters, however.

Ideally, I'd start with a bike fitter who can also advise on physical issues. They might say this is beyond my capability and ask you to concurrently see a PT. You could find both a PT and a bike fitter separately, but try to keep them apprised of what the other is recommending.

As to component-specific issues, here are some possible comments. In general, triathlon favors shorter cranks like 165mm or shorter. At 5' 4", many road bikes come stock with 170mm or 165mm cranks. You're probably in the right size range, but shorter ones exist. If your threshold power is 114W, then in the 50t ring, you are probably at low cadence. In general, if you have osteoarthritis, I suspect you want to try to aim for higher cadence. You might be better off staying in the smaller ring. If you find the cadence in that ring to be too high, then you might be able to get aftermarket big rings that have 46t or so. That might be worth considering. It might be worth considering a sub-compact crankset, e.g. a GRX 600 46-30 crank, but those are made for gravel bike chainlines, and you might also need to change the front derailleur (but it's not guaranteed that you have to).

So, unfortunately, it does appear that you will have to throw some money at the problem - most of which should involve finding out exactly what the problem is. I mention component issues not to encourage you to change cranks, but to alert you that this is a possible issue.

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