Rear Derailleur Rubs on Trainer

Has anyone else had an issue with their rear derailleur rubbing against their trainer when in their lowest gear? I have the H2 from Cycleops and the 6800 Ultegra groupset and I’ve checked all my alignments, everything is fine and it shifts well; using the same cassette as on my actual bike.

I contacted Cycleops and their response was “Long cage derailleurs like your Ultegra can rub on the casing on the H2, there is unfortunately nothing we can do to make it go away. I apologize for the inconvenience.” Less than helpful :-/

Is the best solution to lower the resistance in Zwift and just not shift into the lowest gear?


My Sram short cage RD rubs on my hammer when I’m in the 28. It’s just a design flaw as CycleOps clearly know and aren’t keen to invest the money in addressing.

Hi Marianne,
I never noticed the rear mech rubbing on my Cycleops Hammer before but this week I
put a new rear mech, Shimano 105 5800 short cage (same as previous mech), on my my bike which has 11 speed cassette 11-28 tooth and when setting up the gears I noticed on the 28t sprocket it was rubbing the side of the trainer as you described, I thought it was something wrong with the mech but the mech is fine and it must have done the same with the one before, I can`t believe that Cycleops would design their high end trainers that cost a lot of money to go out knowing this was a happening!!! Unbelievable.

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I’ve been having the same issue and after contacting Cycleops, they’ve suggested the dust cover my be warped. I’m attempting to fix per the picture but don’t hold out much hope of it being a long term remedy since it will likely spring back in to its warped shape fairly quickly!


Bull $ hit. This is a design flaw and they know it. I’ve thought about taking a sander to it but didn’t want to dust to mess anything up on the inside.

Sorry for the necropost, but I’ve run into this same issue with my H2 (as I attempt Vent Top for the first time). Very frustrating. However, I think I have come up with a relatively easy solution that doesn’t involve cutting away the dust cover.

  1. Use a marker to mark where on the dust cover the rear derailleur hits.
  2. Take the bike off the trainer.
  3. Use a heat gun to make the dust cover more pliable. This is a bit of an art form, since the cover is relatively thick. You don’t want to melt the outer surface. So use a middle heat (not highest) and go over a wide area for awhile. It took me 5+ minutes heating up a circle about 8 inches in diameter.
  4. While you are heating the cover (holding the heat gun in one hand), use a hammer or some other device that keeps your hands away from the heat to push the dust cover inward where the derailleur hits the cover. You only need to push it in a few mm.
  5. Periodically release pressure on the cover. You’ll know you’ve heated the cover adequately when you can take the hammer off the cover and it doesn’t spring back. When you get to that point, take the heat off the cover and continue to hold the hammer against the cover for a few minutes while the plastic cools.