Regarding the KickR’s, whether it be Core or Snap
Can a separate PM be used, if so, in ERG Mode would the magnetic brake adjust to suit the output from the non-KickR PM? (the non-KickR PM would also give Cadence)
The spin direction on Core and Snap flywheels are opposite (see arrow graphics/transfers). If some resistance was applied via software, and the flywheel was turned manually/by hand in the opposite direction of the graphics/arrows, would the KickR’s still register Power?
Thanks
Using a separate power meter is a function of the device or app you are using for control. Usually you set the app to read the power from the trainer it’s controlling. Alternatively, you can have the app read the power from a different source and control the trainer accordingly. I’ve tried both and found the response and regulation of the trainer resistance is better when using its native power rather than some other power meter, like a crank or pedal power meter.
IDK about the trainers registering power correctly or at all when rotated backward from their intended direction but I suspect there’d be problems.
Thanks @Saddlesaur 
Hi been thinking about this.
I don’t think there would be a problem running it backward, reason being, they don’t have strain gauges, and calculate power based on resistance (magnetic field strength) and rotational speed (white sticker) of the flywheel… therefore the direction shouldn’t matter. Agree?
I’m curious how they can measure Cadence, i’m assuming it’s looking at the varying Power waveform produced by pedal stoke as there are so many gearing variables 
Yep. Trainers determine cadence by pedal stroke power pulses, 2 per crank revolution. This can work well in normal pedaling against some resistance but not so well at very high cadence, low resistance, and other edge cases. Cadences sensors are cheap, ~$12 on Amazon, and provide reliable cadence data in all cases.
Agree. If you want reliable cadence, use a crank based sensor. Just make sure it’s very securely fastened. I had one fly off on a ride. Secondly, you can use cadence as supplied by a crank or crank arm based power meter.
Would any of you be able to give me this dimension?
The reason i’m asking all these questions is that I’m thinking of converting the magnetic brake on my smart bike to a KickR brake… i’m confident it’s do-able, but wondering how much work would be involved.
Also, wondering what the road feel difference is between Snap and Core, with Core having the additional flywheel up behind the cassette…anyone tried both?
Thanks
IDK, but around here in the US many bike shops have these on display, particularly in the winter. If you can and haven’t yet, checking one out in person may answer many questions, maybe bring up new ones, and give you some new ideas.
Also, one thing you almost certainly have thought of is that any drive mechanism you come up with will need to replicated the ratio of the rear tire diameter to roller dia to get the desired effect wrt resistance and flywheel effect.
Yeah … I’ve got the ratios sorted as my current set up has the pulleys, and a flywheel, so i’m hoping replicating it will be the same feel… difficult to explain! but i’ll show/report back when finished with some pics.
One of the LBS that carried Wahoo stopped. Another will only special order. They had a CORE on the sales floor in box for over a year. They don’t sell well here and for a good reason.
What reason is that, too clement? I was working a big bike shop (7 stores) some years ago and wanted a Kickr. They only carried Saris so I wound up with a Hammer. Now, they have Wahoo out the wazoo, advertising/displaying/selling a ton. They have long snowy winters so not surprising they’d be on the trainer bandwagon during an ordinarily very slow time of the year.
Anyone?, it doesn’t need to be absolutely perfect
They don’t sell enough units to warrant stocking them. Remember we have about 300 days a year were riding outdoors is completely possible. Due to several serious incidents, I’m staying inside for now. I had to buy my CORE online after calling several shops here and asking if they had one.
We have a Snap and that dimension is pretty close to five inches, which if I calculate correctly is 127 mm.
Thank you 