10-speed cassette alignment

My cyclocross bike uses a Shimano Tiagra 10-speed so I purchased a 105 10-speed cassette for the Neo to be able to quickly transition from trainer to ride to trainer (cassette is same part# but bike has 11-32 vs new cassette having 11-28). I attempted to purchase a 1.85mm spacer which I determined thru lots of web surfing to be what is needed to use a 10-speed on an 11-speed freewheel. The bike shop couldn't find the 1.85mm spacer I ordered from them so they gave me a 2.0mm one. 

After getting it all together and readjusting my rear derailer, I'm finding that there is still grinding on the last few small cogs. All good on the larger ones. Could this be due to the 0.15mm difference in the spacer? 

I did put a new chain on as well. Not sure if this be an influence as well...

  • I am not familiar with the setup for a 10-speed Shimano cassette, but according to Tacx Faqx you should use the 1mm spacer that came with the Neo / Neo 2 for 10-speed. If the 10-speed cassette has a recess at the back of the largest cog then you also need to install the 1mm spacer that came with that cassette.

    https://tacxfaqx.com/knowledge-base/installing-the-cassette/

    Is your Shimano 105 cassette recessed or not? I am aware the instructions apply to Neo / Neo 2, maybe it is applicable to Neo 2T as well?

  • Hi. The new cassette does have the recess in the large cog so I included the 1mm spacer. But it appears the combination of 1mm + 2mm might be too much as I can see the chain catching on the smallest cog every few teeth (when also on small cog on the crank). So maybe .15mm less might do the trick but I'm not convinced. I have the 1.85mm on order so I'll find out soon enough. For now, I'm just avoiding the smallest cog (which even on the bike (not trainer) was always a lot louder than the rest and I avoided).

  • I am trying to understand what you mean by the chain catching on the smallest cog every few teeth. Are the inboard outer plates on your chain rubbing on the outboard side of the 12T cog when the chain is on the 11T cog? If so, reducing the spacer width should improve your chain line when the chain is on the smallest rear cog (large or small front chain ring). Whether the 0.15mm spacing reduction fixes the grinding is yet to be determined.

    The 11T cog on my Shimano R7000 105 groupset is also a bit noisy with the road wheel and Neo 2, more prominent on the Neo 2. The noise seems to come from the chain outer plates rubbing on the 12T cog. I rarely ride on the smallest rear cog with whichever front chain ring so it never bothered me enough to get it fixed Slight smile

  • Tx for the follow-up Eric. Yes, the inboard outer plates of the chain are contracting the 2nd cogs (12T).

    Good to know it may be a common trait that it is always a bit louder. I do tend find myself wanting the 11T frequently to avoid shifting to the large crank cog for short stretches...and then once on the large cog up front have the opposite problem when wanting to stay there and shifting to the 26T/28T. But that's the way it's always going to be at the extremes.

    I'll report back when I do the small reduction in the spacer setup.

  • No problems. Let us know how you go. It's different strokes for different folks I suppose. From habit, I only go down to the 13T cog with the 34T front ring to minimise cross chaining. Beyond that, I shift up to the 50T front ring and go back a few cogs on the rear cassette. Not sure if I will ever reach the 11T with the 50T front ring lol.

  • sounds like a good habit...and I might be able to avoid chewing up chains and cogs each season...

  • I found it became 2nd nature after a while to simultaneously up shift the front ring and down shift the rear cog beyond that "tipping" point. And vice versa. Once you know your gear ratios well you know exactly how many clicks to shift on the rear cog to match your speed.

  • If your CX bike sees a lot of use in the mud or sand, I would suspect that the rollers on your chain are accustomed to tooth profiles on the cassette of the CX bike, hence the chain rollers do not seat properly on the teeth of the new cassette on the Neo.

  • I installed a shimano SLX 10 speed 11-34 cassette with recess and I'd swear it didn't come whith any spacer. I only used the spacer that comes with NEO2T and it seems to works fine, but now I have doubts...

  • Dasorsan, are you using the same bike on the Neo and road? My biggest concern with getting the cassette to line up at the same position is to avoid having to adjust the derailer each time I transition from road to trainer to road, etc. I think it is possible to get your derailer set with different spacing but then those settings may not work well when off the trainer