AWD said:
TomTom, it really all depends on when the back of the gear reduction housing hits the chain stay. I have put on quite a few TSD's and you lucked out getting a 51mm chainline on your first try. I had to fit another 42t chain ring on mine because although I didn't measure it the chainline in my 42t in the back was too much for my taste, especially as I do a lot of steep climbs. Lines up perfect with the middle cog on the cassette now. You can go too far though and the ring will hit the nylon cover.
Hi, In my case the gear reduction did not hit the chainstay. The unit seated against the bottom bracket just as the reduction almost touched the chainstay, less than 1mm clearance. I suspect many aluminum frames there would be interference because the tube diameter is larger. I imagine you needed to shim at the bottom bracket, increasing the chainline still further?
In that case an option seems to be to shim the 42T chainring in with 10mm inside diameter washers, but it looks to me like you could gain only 1mm or so.
And then somehow you would need a chainring dished more than 5mm? I'm not following how you bring chainring back in if you have to shim at the bottom bracket.
It looks to me like I was lucky with my fit, that Tongshin designed tightly to a steel frame with 68mm bottom bracket, that the gear reduction is wide enough so chainline is OK only with a steel frame and 68mm bottom bracket?