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Roadbike Rider
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Discussion Starter · #1 ·
Now that I have a second set of wheels for training I find that I cannot just slot in the training wheel without my rear shifting becoming seriously off. Here's the set-up

Race Wheel: Shimano C24 (WH-7900), CS 6700 12-25 cassette and 1mm spacer

Training Wheel: Shimano FH 6700 hub, CS 5700 12-27 cassette and 1mm spacer (I have also tried a CS 7900 cassette 12-27 with similar shifting compatability problems)

The specific problem is not with the limit adjustment but the shifting performance. It could be corrected by increasing the cable tension with the adjuster on the training wheel but I don't want to have to readjust every time I change wheels

Do I have the wrong spacers on one of these set-ups? Can I fix this problem by adding a thin spacer on the training wheel? Is this a difference in manufacturing tolerances on the two hubs?
 

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Matnlely Dregaend
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4,994 Posts
You could take out the spacer on the one wheel where the adjuster needs to be turned to make the cable more slack, but you may hit the spokes on the largest cog. You likely also can't add a spacer because then you'll run out of threads on the lockring, but I guess it depends on how thick the spacer is and how tall the hub is. I would try neither because I just turn the barrel adjuster.

Best solution: build up a bike around the training wheel, now you don't have to change wheels at all! :)
 

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Banned
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Best solution: build up a bike around the training wheel, now you don't have to change wheels at all! :)
Things only a true cyclist would say. "You got a whole rear wheel, build a bike around it!"






Got handlebars? Build a bike around that. lol wtf.
 

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Now that I have a second set of wheels for training I find that I cannot just slot in the training wheel without my rear shifting becoming seriously off. Here's the set-up

Race Wheel: Shimano C24 (WH-7900), CS 6700 12-25 cassette and 1mm spacer

Training Wheel: Shimano FH 6700 hub, CS 5700 12-27 cassette and 1mm spacer (I have also tried a CS 7900 cassette 12-27 with similar shifting compatability problems)

The specific problem is not with the limit adjustment but the shifting performance. It could be corrected by increasing the cable tension with the adjuster on the training wheel but I don't want to have to readjust every time I change wheels

Do I have the wrong spacers on one of these set-ups? Can I fix this problem by adding a thin spacer on the training wheel? Is this a difference in manufacturing tolerances on the two hubs?
Hubs aren't totally consistent about where the stop that locates the cassette is, exactly.

Since you have to increase the tension on the training wheel, that cassette is further from the centerline. I'd try spacering the cassette on the race wheel to match it. You could also try milling down the spacer for the training wheel, or substituting something thinner, but I'd be a little nervous about that for the reasons brought up earlier in the thread.
 

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Roadbike Rider
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1,260 Posts
Discussion Starter · #7 ·
Or adjust the axle nuts (or add shims) such that the locknut to gear distance is the same on both.
That might work. Thanks for the suggestion
 

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Roadbike Rider
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1,260 Posts
Discussion Starter · #10 ·
That worked. I needed to move the axle inside the hub to decrease the drive side space by about 0.3 mm on the training wheels.

The only tricky part was measuring since I couldn't touch both surfaces with the digital calipers, I had to sight along the edge of the caliper to align it with the face of the axle nut. A depth gauge would have worked much better

Thanks again.
 
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