Wednesday, December 19, 2007

Indoor trainers causing knee problems

Indoor trainers causing knee problems
Like many cyclists, I am now settling into a long winters worth of indoor training sessions on my trainer. I currently have my bike hooked up to an Elite fluid trainer with my front wheel up on a block.

My question is related specifically to knee pain experienced while riding on the indoor trainer only. For the last two seasons I have been getting pain in my left knee, just under the knee cap. I only experience this pain when riding inside, never outside. At this point in the year I am spending most of my time spinning comfortably in mid 90 rpm range with concentrated efforts to simulate climbing a couple days a week for a total of 5 - 6 days of training per week. My knee doesn't show any signs of swelling but does seem to tighten up after a long ride.

What could be causing this knee pain and why does it only present when on a trainer? Given that my position hasn't changed and my workload is really pretty easy right now, the only thing that I can think of is that it has something to do with the bike trainer combination. My thought is that the bike, while mounted on the trainer, has no give so any natural movements or quirks are being stopped by the trainer whereas they would normally be absorbed into the natural movement and flow of riding on the road. Of course I could also be on the completely wrong path which is why I am writing to you.

Any help or direction that you could provide would be greatly appreciated.


Steve Hogg replies:

G'day Jason,

Assuming the bike is level on the trainer and given what you say about riding under moderate load only, the most likely reason for your problem is the lack of momentum of an indoor trainer compared to you and your bike on the road. Indoor trainers have relatively small flywheels and when flywheel momentum and the roller momentum is added to the weight of your rear wheel and crank rotation etc, it is still only a fraction of momentum of you and your bike on the road.

That in turn means that on an indoor trainer, pedaling technique differs anything from slightly to massively.

Here is a test; next trainer session, twist your left hip forward a touch when the knee niggle starts.

If that arrests the niggle, then either your seat is too high by a few mm on the trainer and you are autonomically choosing to self protect the right leg and sacrifice the left (very common) by mildly twisting the right hip forward OR you are already doing that on the road but the technique you adopt on the trainer causes you to drop your heels more and again, you choose to protect the right side as described above. Either way, drop the seat 3 - 5 mm and let me know what happens.

If twisting the left hip forward (and it will seem forward to you but if I am right, that forward movement of the left hip will be squaring up your hips) doesn't eliminate the niggle when it arises, get back to me for more advice.

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