Chain slipping on Tacx trainner

I bought the new Tacx smart trainer and put my cervelo road bike on the trainer.  While pedaling, the chain slips.   I am guessing that this is because the chain fits the rear cogs of the bike and not the trainer.  I called the bike shop and they said new drivetrain will cost 400+ but even then the chain will conform to the road bike over time.   Is the only soln. To buy a bike dedicated to the trainer?  If I buy an older used bike will I have to also upgrade the drivetrain?  Thank you!!! 

If this is a direct drive Tacx, the cassette on the Tacx should match the one on your rear wheel.  If it doesn’t have it changed.

If the cassettes match then check your chain.  It may. be due.

Thank you Jenna.   I will do that.  That’s a big help!!!

Jennifer, if your chain is worn and the cassettes in the trainer is brand new , this may results in slippage because the chain spacing and cassette dont match.  The other possibility is that you need to readjust your derailleur slightly for the trainer.  You would also notice poor shifting and noise.  Take a ruler and align the edge on a chain pin to the zero mark.  The 12" mark should align with the start on a pin.  In the pin is more than 1/8 of an inch beyond 12", the chain is toast.  I say shame on your bike shop to suggest that you need to spend big money. 


Thank you David!  That’s very helpful.  I think I will take the bike into the shop for a tune up.  It is much overdue.  I’ll have them look at the chain.  If it still doesnt work, I’ll see if I can pay someone from the bike shop to come look at the setup.  It’s possible the bike shop didnt understand the problem,

Chain slippage means something or multiple things in the drive chain are worn or misaligned.

You probably will need a new chain, check the stretch with a tool or measure.

Usually, when I have had a chain slip, it was slipping on the chain rings because the chain rings were worn.

I have never had a chain slip on the cassette.

The metal that the cassettes are made of seems much harder than the surprisingly light and flimsy chain rings.

Of course, if your derailleur is not shifting completely, you need to adjust your cable tension or put on new cable or housing.

I have, pulled the old cable lubed it with chain lube wiped it dry and reused it.

You should be able to fix your problem for much less than $400 but the shop has the expertise and knowledge that many riders don’t have and they deserve to be paid.

That’s ok.

Same thing happens with my truck -why was I paying $300 to change brake pads?

I had the same problem. Turned out the new cassette I bought for the Tacx Neo was the wrong one. I put the one from the bike on and it runs just fine. New one fitted to the  wheel also runs just fine. 

I had a brand new Shimano Ultegra 10-speed cassette that purchased a few years ago that I never used.  I stored it with a nylon zip tie running through all the gears and spacers so that they’d remain exactly in the order that I received them in the package.  I installed this cassette on my Tacx Neo.   I had no chain skipping until I shifted to the 3rd and 4th smallest cogs.  I watched many YouTube videos explaining how to fix chain skip (particularly in middle cogs).  One by one, I made the following changes:

  1. Followed a number of different instructions for setting my index shifting.

  2. Installed a brand new chain and ensured there were no tight links.

  3. Eyeballed my derailleur to make sure it was not bent (at least it looks straight to me).

  4. Installed a new rear derailleur cable after reviewing a number of YouTube videos for proper installation. 

After all this, my chain still skipped on the 3rd and 4th smallest cogs.  I decided to remove the cassette and make sure that the cogs were all properly installed.  I read somewhere that cogs can only go on one way except for maybe one cog (don’t remember which one) that could possibly go on two different ways.  When I took off the cogs and spacers, I kept them in the exact order that I removed them which would be in the exact order that I stored the brand new cassette with the zip tie running through it.  I then took my time and slowly re-inserted each cog and spacer onto the cassette.  When I got to the 4th smallest cog, lo-and-behold, I found that the number of teeth was stamped on the side of the cog that I had facing inside.  I found the same to be true of my 3rd smallest cog.  All the other cogs had the number of teeth stamped on the side that faced out.  I now inserted those 4th and 3rd smallest cogs with the stamped number of teeth facing out.  When I was all done, and as you would guess, I had no more chain skipping!  Sure I could have made a mistake with cog storage somewhere along the way but I am pretty meticulous and truly feel that I received those 3rd and 4th cogs from Shimano flipped inside out.  I have read on a number of web sites that you cannot insert cogs onto the cassette incorrectly because of the way they line up.  But I can tell you that it was possible for me to insert the 3rd and 4th cogs inside out onto the Tacx Neo cassette.  My Tacx Neo is the model with the W 2017 stamped on the box.  The cassette accommodates Shimano and Campagnolo cogs.  I understand that 2018 model handles cogs differently.

I am now riding along happily with no chain skipping.  I hope this explanation helps someone else.