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dvai 01-31-20 07:47 PM

Knee pain in trainer but not on the road
Hi guys. I need help.

I got a bike fit when I bought my bike 3 years ago. On the road, everything is perfect (long rides, shorter faster rides, etc). Last winter I got a trainer and subscribed to zwift. I loved it, BUT I started feeling knee pain (mainly on the back) to the point I got tendinitis. When the spring came and the road riding season started, I rode perfectly.. no knee pain or anything. I attributed the issue to pretty hard riding on Zwift and moved on.

Now again back to Zwift and Im getting the same symptoms. Even with easy rides.

I dont understand why there is a difference, especially since I ride much more outside. The bike fit was done with the bike on a trainer...


melikebikey35 01-31-20 08:33 PM

On the road, you are constantly shifting position. Whether it's shifting weight balance while cornering, getting out of the saddle for a climb/sprint, or simply from the bike rocking side to side while pedaling, you're constantly using your muscles/joints differently. On the other hand, when you are on a trainer, you're essentially locked into place. Which puts extra stress on certain's just the nature of indoor training.

However, if it's too the point that it's causing an injury, you might look into changing your position, slightly, while indoors. For back of the knee pain, I'd try lowering your saddle a few mm.

Carbonfiberboy 01-31-20 11:40 PM

I don't know what trainer you're riding, but they are different. My wild guess is that on the road, you have a tendency to push down on the pedals and then let the momentum carry you along until the next pedal stroke. On the trainer, especially those with small flywheels, there's not as much momentum, like if you stop pedaling the thing just stops. On the road, you keep coasting, if you see what I mean. So you maybe have more of a tendency to pull back on the pedals or in other ways try to prolong the pedals stroke on the trainer so the thing keeps spinning along. Maybe. In any case, try lowering your saddle about 5mm, see if that helps. Maybe even a full cm. The saddle has to be at a just right height to facilitate other than just push-down pedaling.

canklecat 02-01-20 01:32 AM

Ditto, the above. Gotta remember to shift positions on the trainer. Even if I'm doing my recovery ride/easy spin on the indoor trainer, I'll stand to pedal awhile every so often, and scoot around on the saddle a bit.

I also discovered that while I like my old Biopace chainrings on the outdoor bike, I don't care for 'em on the Cycleops trainer. It exaggerates the pulsing, lunging sensation. On the road the slightly elongated lobes, especially on the smaller chainring, give just a tiny bit of leverage on the downstroke. But on the Cycleops trainer it feels herky-jerky and made my knee ache a little. I'll set aside the Biopace rings until I finish rebuilding the bike they were on last year. That bike needs headset servicing and lots of TLC.

Never had any problems with regular round chainrings on the Cycleops trainer. No idea about rollers, haven't used 'em.

Seattle Forrest 02-01-20 12:30 PM

Don't give yourself tendinitis again. As you know it's incredibly painful and takes so long to heal.

sdmc530 02-01-20 02:12 PM

I too have this problem with Zwift. If I ride over 90 minutes I have knee pain too, I just make sure I don't do that and remember to stand and ride. Also every 30 minutes I jump off and walk on the treadmill for 5 minutes and do a few quick stretches. That has keep the pain away for me.

canklecat 02-01-20 07:30 PM

Yeah, don't "push through the pain" with knee twinges. That never works on joints.

And change positions often. With marathon indoor trainer sessions I get off the bike about once an hour, usually between episodes of whatever TV series I'm binging. Same outdoors. If I feel even a twinge in the knee I'll stop for a few moments, stretch and walk around, maybe adjust the saddle/seat post. I'll ignore most muscle discomfort, but not knees or other joints.

dvai 02-01-20 08:58 PM

Thanks guys. This is very helpful and makes a lot of sense.
I will lower the seat a bit and see what happens.

(and yes.. I learned my lesson.. don't push through the pain)

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