I usually don’t have any issues with my outdoor bike, but my indoor bike (which I used to ride outdoors) gives me constant left knee discomfort.
Both bikes have roughly similar geometries and positions, but I can’t get them exactly the same because:
Different saddles (ISM vs Prologo)
Different seatpost setback
Different Q-factor (+4 pedals vs standard pedals with two 1.2 mm washers each $$$)
Slightly higher bars and less reach indoors for comfort
Should I bite the bullet and get another ISM so I can dial in the seat position exactly?
Would another 1.6 mm per pedal actually make a difference worth spending $100+?
Or is this just a case of indoor training causing bike fit issues to become more apparent?
I might just have to take the time to through my outdoor bike on the trainer.
I recently started getting slight knee pain on one knee after 15 years of issue-free riding - assumed it was a combo of a new bike and new shoes (cleat setup).
Went to see my friendly physio/bike fitter and he instantly said my knee was tracking inwards slightly on my pedal stroke and to keep a focus on making sure it only goes up and down piston-like in one plane of motion. Few drills over the next few rides and its sorted and all pain gone. Apparently knee pain is so common because all the muscles attach around the knee so any imbalance or pedal stroke issues manifest at the knee even though they arent specifically knee related issues.
I only add this example as it may be worth taking a bit of time (and an observer) to have a look at your pedalling motion etc on the bike and see if there is an obvious issue and fix that doesnt involve changing any kit. YMMV of course but at least this is a free fix and sorts longer term issues that would keep coming back anyway.
I have my indoor bike setup identical to my outdoor bike (same seat too) and training indoors usually always leaves me with cramps and minor strains all over my calves and hamstrings.
I’ve gave up trying to ‘dial it out’ and have turned to an unholy amount of stretching, icing and just yesterday picked up a massage gun to add to my regimen.
I use my TT bike on the trainer and obviously in TT races but I also do a fair bit of road and gravel biking and it would be impossible to recreate my position exactly in all environments. It might not have been related but when I used to use ERG (perhaps the low-mid range Suito might be the problem is more of the problem with ERG) I would sometimes get knee discomfort indoors with perhaps the different set ups. I’ve switched back to resistance mode (I used it prior to joining TR) and touch wood I seem to be getting good results (no knee pain and faster).
I would get the same saddle and get it in the exact matching position as you outside bike, assuming your outside bike is in the correct position. Remember, when riding inside, you move around much less, so if so,ething is off, it will most likely cause problem there opposed to out side.
Also trainer put stress on your knees a little different due to flywheel momentum. I definitely push more over the top of my pedal stroke inside compared to outside.
I threw my road saddle (which I used to use indoors) and +4 pedals on my indoor bike and it was much more comfortable. I probably still need a bike fit, though. I might try adding spacers to my extended pedals. I figure if it feels good on a trainer it will be perfect on the road. My hips are probably not meant for standard Q factor…
Trying my +4 pedals with two spacers was yet another improvement. Indoor training hasn’t been this pleasurable in a long time. I swear it seemed to even make my shoes more comfortable.
Now I need to buy more washers and some more extended pedals…