I've got an 8-speed Mérida road bike (that is, 2x8, 2 front, 8 rear) that I'm fitting to a 2020 (v5) Kickr that I just bought new. I am learning about some bike mechanic stuff that despite many years riding I've been ignorant of: indexing the gears, adjusting the cable tension, the H and L screws, the B gap screw, etc.
With the help of my bike shop (I bring them videos of the problems and they comment, since the Kickr is heavy to transport), Wahoo tech support, and this forum/group, I've got the gear shifting pretty smooth, and corrected a clicking sound on the lowest (largest) gear in the rear cassette by adjusting the L screw (although today, for a little while, there was a clicking sound on the second lowest gear). However I can't seem to get rid of a lot of chain noise and a rumble that can be felt through the whole bike when I'm on the highest (smallest) gear on the rear cassette. I've tried adjusting the H screw back and forth (this is what Wahoo suggested), but I only make it worse. That is to say, when I turn the H screw too far in one direction, a clicking starts to come in, which is understandable. If I turn the H screw back to where I had it, the clicking disappears, but the rumble remains.
Again, the more central gears on the rear cassette work fine.
Could you take a look/listen to the linked video and see what you think? The noise isn't that noticeable in the video, but immediately I switch into the highest gear there is a lot more chain noise and there is a lot of vibration that comes up through the frame into the handlebars and seat.
I think it's important to note that I am in the lower gear in the front derailleur, that is, I am on the smaller gear in front. So I'm wondering whether this all might be explained by cross-chaining (more noise, but not as much, also occurs with the combination of highest front/lowest rear). That it's cross-chaining seems logical, but it's a bit odd that the second-to-highest gear in the rear doesn't create an issue, and the noise suddenly gets much larger and a rumble starts when I jump to the highest rear gear. Perhaps that's because with an 8 gear cassette there's a large jump? I don't know -- my other bike (never used and never to be used on the Kickr) is 2x10, so perhaps a bit more graduated.
In any case, one answer would be to just avoid this combination, low front/highest rear, but I'm keen to understand what the issue might be. If I can solve this myself, I won't have to take the Kickr in to the shop, which would be a lot of trouble, given the weight.
In any case, this won't damage the Kickr or bike (frame)? It just might add some wear and tear to the cassette? That's what my bike shop said -- I'd like to continue to use the Kickr while I sort this out.
(One thing to note: the bike shop replaced the 11-speed Kickr cassette with an 8-speed Shimano, and (I was told) added the Kickr spacer that's to be used with smaller-than-11-speed cassettes)
Any advice much appreciated!
