172.5 vs. 175mm crank - knee tendinitis - need help

Greetings to everyone:

In very early February I developed a case of patellar tendinitis in right knee during one of our training crits, due mainly to going too hard too fast after getting back into cycling last August. It happened on my old bike with 172.5MM cranks. Right after this I bought my new racing bike which came with 175 mm cranks and have been riding on them since. The new bike fits me perfectly in every way except for the cranks...172.5 is what is recommended for me.

I trained and raced throughout Feb and March, tried to manage soreness, then took first 3 weeks of April completely off the bike. Finally went to doctor during that three week period, who put me on Naprosyn, recommended icing, and light riding 3-4 times per week to build up collagen and strengthen tendon. He said physical therapy probably not needed.

Well, after about 2.5 weeks of light riding (strictly high cadence, low gear, Z1-2 riding), stiffness and pain is still there, though reduced, typically hours AFTER a ride (I really don't feel pain during the ride). So, I am going to seek physical therapy.

HOWEVER, I am interested in getting your opinion as to whether going back to 172.5MM would help with the recovery (less extension of leg)? For what it's worth, I've had three bike shops verify my bike fit, I had one shop install the LeMond wedges to correct slight pronation, and the bike fit RECOMMENDS 172.5mm crank for me. So my current crank is technically too big, though I am not sure it would really make a difference for the tendinistic issue...YOUR OPINIONS?

Money is not an issue. Also, the "advantages" of the longer crank (e.g., leverage for climbing and time trialing) aren't really that important for me here in Florida as we don't have climbs and I don't do lots of time trials. In fact, I think the smaller cranks would help with the sprints we have in these fast, flat crits.

Any thoughts/opinions as to whether to switch back to 172.5s?

Thanks in advance.

Mark

 

Mark
The 175 crank arms will place greater pressure to your patellar tendon at the top of the stroke due to increased knee flexion. The increase is actually two fold because at the bottom of the stroke your foot will be 2.5mm lower than with the 172.5s. Your saddle will have to be lowered 2.5mm just to keep your leg extension the same. Now, at the top of the stroke the 2.5mm longer arm places your foot 2.5 HIGHER relative to the shorter crank. Add in the 2.5mm that you lower your saddle, you will essentially have the same knee flexion at the top of your stroke as if you had lowered your saddle 5.0mm.
Get the 172.5s. With Patellar tendinitis knee flexion is the enemy. When you get fitted go for a knee extension angle closer to 160 instead of the usual 150-155.
And yes, you're absolutely correct. The shorter cranks are better suited to sprints and fast cadences.

 

Thanks Insane - your comments confirm what I was thinking. Although the shorter cranks won't "heal" the injury, once it is healed they will act to prevent further aggravation I think.

In another forum, a person who struggled with the same issues suggested, when I gave my height (5' 10.5") and inseam (84.1cm), suggested going with 170s.

I go to PT next Tuesday and will relay all this information there. I will also ask the bike shop about the crankset; i.e., whether 172.5 or 170 is the way to go given the type of riding and racing I do.

Thanks again, and I'll give an update.

Mark

 

I also have slight foot prognation. Is the wedge on the inside of your cleat? Can you tell they help? I have been dealing with patella femoral sydnrome and my prognation might be a part of my problem.

 

FYI - I use LeWedge with Speedplay pedals. Before using the wedge, my feet would try to "wander a lot on the pedals" looking for the right position. With the use of three wedges to compensate for my pronation, I find my feet much more stable in the pedals. From this, I have to conclude that they help.

 

**UPDATE**

Just wanted to let everyone know what happened at PT. PTist took a lot of time to move my legs in every direction possible to test flexibility, and also did some minor strength tests. She confirmed the physician's diagnosis of patella tendinitis, and said she felt nothing structurally wrong with the knee. She said the kneecap is floating a little bit, but that's probably due to the fluid build-up. Her ideas as to what is contributing to knee pain are:

1. My right quads are less flexible and slightly less strong than my left leg (where there isn't any knee pain).
2. My hamstrings are very flexible (I do stretch these quite a bit), but comparatively weak.
3. My calves are comparatively weak.
4. She does not think it's chondromalacia, as there does not seem to be abnormal imbalances between the strength of the three quad muscles.

Interestingly, my knee was more sore this morning, which I attribute to all the twisting and stretching she did of my leg yesterday. In short, she thinks strength and flexibility imbalances between different muscle groups on my right leg could be contributing to the pain. She doesn't think it's serious, as there is just a little bit of fluid, but has cautioned that I should not go hard until the pain has subsided. She has prescribed...

1. 2x daily stretching of the specific quad muscles that are tight, before and after riding/exercise.
2. Ice knee post ride ( I actually do this several x per day)
3. Continue with Naprosyn
4. PT 2x per week (stretching, ultrasound), for 3 weeks.
5. After three weeks of stretching to increase range of motion, she will then focus on several weeks of strengthening the specific muscles that could be contributing to this. She doesn't want to do this now as she thinks the 1 hour of cycling I do 4x per week is enough strength training for now, and she wants to focus on flexibility first.

Personally, the skeptic in me can't see how some extra stretching exercises are going to all of a sudden make the pain go away, but I will give it a try.

Oh, she saw the logic behind getting smaller cranks, but doesn't think at this point that's a step that will help in recovery and therapy. She wants to try the above first before making structural changes to bike. She also recommended I stick with floating cleats rather than fixed. Given all the positive feedback on Speedplay pedals and how they help relieve knee pain, I will need to look into those as I move forward. I'll still probably get smaller cranks once I do gear things back up.

Thanks for all the help and comments, even if you have any on this post.

 

I have gone from 175 to 172.5 and did notice an improvement for my knee.