The Rear Derailleur Cage Is Rubbing against My Tacx Neo 2T

When installing the cassette on my Neo 2T trainer, I have to use the additional spacer to prevent the rear derailleur cage from rubbing against a rotating part of the trainer when the chain is around the innermost cog. Inserting the additional spacer moves the entire cassette outward, and alters the chainline. Consequently, the front derailleur no longer trims properly. For example, when the chain is running between the middle of the cassette and the inner ring of the crankset, it rubs the outer cage plate of the front derailleur. I could adjust the front derailleur to compensate, but then it would be out of adjustment when I mount the rear wheel to ride outdoors.

The other day I described the situation while chatting with someone in support. Eventually they asked me to send pictures. I didn't have time, and I'm really not inclined to do so since this is a problem about which Tacex is well aware. It's the reason they ship the Neo with an extra spacer!

The problem with the Neo necessitates one derailleur set up for indoors, and another for outdoors. That's something I'd really rather not be bothered with. It would be nice if Di2 provided a way to save multiple configurations. Then I could simply switch between configurations as needed.

Recently I brought my bike along while traveling to another state. I wanted to be able to ride indoors, but didn't want to haul the Neo. Consequently, I ended up renting a trainer once I reached my destination. I didn't specify a particular brand, and they sent me a Wahoo KICKR. The KICKR does not have the problem that the Neo does. The chain line remains true, and there is no inordinate rubbing. I didn't realize how much that annoyed me until I no longer had to tolerate it.

The Tacx Neo is a great trainer, about which I really have only one complaint. I was hoping that a couple of years in, the folks at Tacx might have come up with another solution. Short of redesigning the trainer, I really can't imagine anything else that would work. If anyone has any ideas, I'm open to suggestions.

  • The trainer comes with two spacers to place on the axle behind the freehub body.  I had the same issue and it took me a bit to figure out how to address the issue.   Once I did this all was good and my SRAM eTap 11 speed RD works fine and needn’t be adjusted when I take my bike off the trainer and install a wheel.

  • I'm sorry about this delayed response, but I haven't been on my bike neither indoors nor out since last November.

    Okay. If I understand correctly, you're saying that the spacer(s) provided by Garmin are supposed to be installed behind the freehub body and not behind the cassette. To be honest, it has been so long that I can't remember where I installed the spacers.

    Just to clarify, the chain is not rubbing against the front derailleur cage when the rear wheel is mounted. It's only when the bike is mounted on the Neo that the problem occurs. My assumption is that it's because installing the spacer(s) moves the rear assembly outward, thereby changing the orientation of the chain relative to the front derailleur cage.

    In the next couple of days I'll be setting up the trainer again. I'll take a look at what I did. Perhaps there is a compromise – like fewer spacers or a thinner spacer. However, my recollection is that I had to install the maximum number, or largest spacer to prevent the rear derailleur cage from rubbing against the trainer. We'll see.

  • Hey there. Is there any update to this? I have a very similar situation. Installed the same 12 speed cassette that is currently on my road bike (CS-R8100) that uses di2. When on the innermost cog, the RD rubs. Garmin instructions say it should just work as the 12 speed cassette is HG. I'll give the spacer technique a try, but I'm also worried that the chainline being different.

  • It has been many months since I revisited this issue. The last time I rode my Tacx trainer was in November of last year. Shortly thereafter, I spent the next couple of months moving to a another state. Since that time, my trainer has not seen the light of day. However, none of that answers your question.

    The problem persists, but I haven't been on the trainer for quite a while. Eventually, I do intend to resume an indoor training regimen. Frankly, I don't see a solution that makes sense for me.

    The cassette mounted on my Neo is a Shimano Ultegra CS-R8000 (11-28) 11-speed cassette. The front and rear derailers on my bike are from the 8000 series. The rear derailer is of the long-cage variety, which I believe used to be identified with a GS designation.

    I'm wondering whether this problem is confined to Shimano components. Short of adjusting the front derailleur, I really don't see a solution. I don't know whether changing out the rear derailer would make a difference. I thought I heard a rumor that this might not be an issue when using a derailer with a standard cage – although I don't see how that would make a difference. I'd rather not have to adjust the front derailer every time I switch between indoor and outdoor riding.

    I'm sorry I don't have anything more to offer at this time. I should be setting up the Neo within the next month or so, at which time I'll take another crack at it.

  • I am having exactly the same issue with my pinarello dogma f12 with a 12 speed cassette .

    rear derailleur touches the neo when I shift to the inner cogs .

    I did use the spacers: one on the ND side to create more space for disc brake pad, and one on the D side (inside the hub) to create more space to avoid the rubbing effect of my rear derailleur when I shift on the inner cogs.

    I tried different things: with spacer - without spacer. 
    notning seems to work.

    pretty darn disappointing, I am planning to get rid of the neo as I am afraid it will mess up my shifting system


  • is the rear cage is 100% vertical ? (didn't you have any accident or just bike fall to the right side?)

  • I didn’t have this problem until I recently installed a new chain.  Nothing different other than it’s new.  I’ve installed the larger spacer that sits on the outer radius.  It had no impact.  I tried installing the two smaller spacers that fit directly on the thru axle and they don’t fit.  I’m hesitant to try and trim my derailleur with the AXS app because with my wheel on it’s fine.  I’m sure I’ll solve it but it’s really annoying to miss training time and the loss of using my large gear until I do.

  • I had the same issue, but it solved it using felt furniture pads, the things you can put under your chairs, tables etc. so it doesn’t scratch your floor. 

    I just checked where the derailer was hitting on the trainer and placed a furniture pad right there, since it wasn’t rubbing so much for me it was just enough to make it annoying because of the noise this solved the problem.

    I tried using the spacers that came with the trainer but that wasn’t enough and the rear derailer don’t seem to be bent either for me so felt furniture padding was the solution for me.

  • Thanks for the tip of using the felt pads. My Dura Ace 12 speed rubs on the unit itself, not the flywheel and it makes an annoying sound. I will also check the derailleur hanger as suggested above.

  • What’s the size of your biggest gear.  Mine is 33 and it just won’t make a difference what you do.  It’s going to jump up to that larger gear and it’s going to move the derailleur in with it.  You’d think that Garmin would have an answer for this?  Also is yours a short cage?  When I switch to my 28T problem goes away.