Was doing some low cadence work yesterday, down around 60 rpm, and my Kickr started to “slip”, as in something within the resistance system was letting out for a quick moment and my feet would jump forward for a split second. It felt similar to a missed shift where the chain doesn’t properly catch, but I was in Erg mode and wasn’t shifting gears at that moment. It did this “skipping” regularly until I picked my cadence back up to >80 rpm.
So obviously at low cadence the flywheel speed is low, but the resistant torque is high. It seems like something within the resistance system is either worn out, or perhaps the limit of some component is being exceeded.
That type of resistance system will have a max torque value just due to the limitation of the size of magnets or field it can generate, as well a peak power output (total heat generated). Ideally, they would provide some sort of peak "power curve over a RPM range of the resistance unit. Even better then, a chart showing peak power available at different gear inches and pedaling cadence.
You might try using a higher gear ratio to increase the resistance unit rotating speed.
Out of curiosity, what gear ratio were you in at the time. In erg mode it won’t matter to you, but it will def. matter to the resistance / flywheel system.
Please try again in the big gear / little cog and report the results.
I was in a TrainerRoad interval targeted at 311 W. My gearing was 54-25 when it happened, so yes the torque value would have been pretty high. When picking the cadence back up to a higher value again, the slipping stopped. So while the solution may be getting the flywheel spinning faster by either using a higher cadence or a faster gear, I was just curious if others have also experienced this.
That’s funny, this just happened to me today after using my Kickr for almost 2 years. I took a look, and my belt drive actually cracked in one spot and the teeth don’t line up in that part of the belt. Not ideal! I’m thinking it needs a new belt, at a minimum. I just submitted a support request to Wahoo.
Take a look at your belt and see if there’s a point where the teeth don’t line up anymore. It helps to take the face plate off, but you probably don’t need to.
Hmmm, good question. I’ve never experienced my chain slipping on the cassette before, so did not suspect it could have been that. I’ll give it a try tomorrow to confirm.
I installed Force1 back in November, so new chainring, chain, cassette, and RD at that time. Been putting between 4-7 hrs/week, so “kind of” recently.
That type of resistance system will have a max torque value just due to the limitation of the size of magnets or field it can generate, as well a peak power output (total heat generated). Ideally, they would provide some sort of peak "power curve over a RPM range of the resistance unit. Even better then, a chart showing peak power available at different gear inches and pedaling cadence.
You might try using a higher gear ratio to increase the resistance unit rotating speed.
+1
I think Kurt Kinetic provided a chart just like you describe.
To the OP, you’ll find the minimum rotational speed at which a give resistance can be provided will vary little, where possible sources of variation will be measurement device offsets (kickr, pm) and operating temperature; to name a few. So you might skim the limit one time and then find it slipping on another.
so i confirmed that it is the belt. i found a slightest amount of fraying on the side of the belt, was only about 2-3 cm long. Although the slipping didn’t happen every time this frayed section went through the tensioner pulley part of the system, the only time it would happen is when it was going through that part. I got my wife to take a slo-motion video of the belt going through there, and only when the slipping occurred you can see the belt rising a slight amount off the drive wheel, obviously meaning the belt’s teeth weren’t sitting properly in there. After the frayed section passed this point, the belt then sat down properly again.
Sounds like its time for a replacement belt. Thanks for the suggestions all.
Hi, if you are going to get a new belt, You might want to try the one specifically in this link. I have reduced the upper frequency scream in mine significantly by swapping to this belt.
Optibelt Omega http://www.kramp.com/...t+Omega+170T+-+15+mm
I appreciate that this is a subjective thing, but would recommend this to anyone who finds high pitch sound objectionable.