Hi all,
I finished a coach Jack ride in erg mode.
Throughout the ride, power was not clipped/limited from the top, allowing me to go over the wattage set in the workout.
Is that a problem on my side? Are my settings wrong? A hardware problem?
Up till this ride, power was set by the app, as you’d expect for erg mode.
I’m using the app on android to control my Wahoo Snap (wheel-on) trainer.
Screenshot:
I’m using the app on a Samsung Galaxy M13 android to control my Wahoo Snap.
I also have a cadence sensor (Cospoo) and HRM (IGPSort).
This exact setup worked flawlessly until today.
Sounds like you might have been in too big of gear so even at minimal resistance with that gear it was higher than our target. Generally it sounds like something on your side with your setup. Maybe calibration issue but that seems less likely.
I think I was on a pretty big gear, yes.
This bike is an old 3X9 mtb, and I was on the big chain ring.
So I guess going with the middle one will solve my problem?
Any guesses as to what might have changed to cause this issue? Maybe the tire (it’s a wheel-on trainer) being too worn?
It’s probably not a calibration issue. The last thing I did before this ride was a spindown, which is the calibration as far as I understand (feel free to correct me 
).
Thank you for your help!
Yes middle gear will likely solve the problem. If you are saying one day you could hit X watts and the next day you could not hit X watts and you were in the same gear and did a spin down both days it’s a bit strange but some small factor could have changed like a bit more wheel slip the first day… Not sure. Just try middle ring and see if that fixes your problem. Let us know 
I did a ride today on a much easier gear (middle ring plus a bigger ring on the back) and for the most part the trainer managed to hold me down at the prescribed wattage. When I shifted to a faster/harder gear (i.e. smaller ring on the back) the trainer “gave up” and let my power go up.
When the wattage was lower in the program, I could easily ride “harder”.
You can all of that in the screenshot:
So is this really a resistance issue?
Can it be caused by slippage?
My tire has become pretty much smooth. It still has treads, but the higher parts are so smooth they’re shiny
Another clue (maybe): when cadence is low, pedaling feels strange, maybe even as if there some slippage (but I’m not really sure how that would feel).
I am not an expert in wheel on trainers. I would think slippage would cause drops in power not increases. So from my perspective this looks like very good power matching target so I would not worry about any of this, just keep in a smaller gear… Yes low cadence can also require higher resistance by the trainer to hit the same target so could cause some slippage or even power overages in too big of gear.
What´s the target power for that workout?
Wheel-on trainers have a significant minimal resistance. I remember my former Tacx would not go below 55-60W even on the easiest gear at a cadence around 80 rpm.
I replaced my super worn tire with a less worn one, and the trainer could cap the power on a bigger gear than before, as well as at low cadence.
For it to cap my output at a very lower power target (60w) I need to be in a really big/easy gear.
All in all, I think I can live with that.
I’m still interested to know what exactly is happening and why.
Follow-up question: can I trust the power data from the ride where the trainer reported output above the target throughout the whole ride?
Power meters from wheel on trainers are not super accurate in general. Are you using an external power meter? If so this is likely more accurate than the one built into the trainer. But in general “trusting accuracy” is not so important because the relatively small differences don’t have much or any impact on your actual training.
Cycling math vs your physical body on any given day is not necessarily a high level of precision as far as the exact training benefit goes. If you slept really well last night your body might benefit from slightly harder training and if you slept worse it might benefit from a little less. These are generalizations and not universally true.
I would say what you are doing looks great and don’t worry about it Don’t kill yourself in training, gradually increase intensity over time, the last 6-8 weeks before peak season or an important event should be hard, and can border on very hard. I suggest you save killing yourself for times when it is fun, usually this means outdoors with some friends or a race. Don’t kill yourself too early too often and you will be good.
Which brand/model trainer do you have?
A lot of wheel-on trainers can be used non-powered (in a very basical way like a non-smart trainer) and have a built-in mechanical resistance curve that is purely the result of speed. If you have such a trainer, the resistance from that power/speed curve is the lowest you can go. Once powered, resistance can be higher because of the supplemental magnetic resistance that is created. Since you are talking 60W, I’m pretty sure that this is what you’re experiencing. Disconnect power from your trainer and ride it like that at different speeds to check if you feel a similar resistance at similar gearing/speed.
See here
Wahoo Kickr Snap
