Incompatibility between seat stay an cassette in R20
"A picture is worth a thousand words". So, 2 pictures might worth 2000 words !
On the upper cog I can get a couple of millimeters clearance between the chain and the seat stay.
I have some ideas of mine, but please, help me solve this problem so I can get full use of 7 cogs of the cassette
I saw somewhere (shoot I can't remember what site it was...) where someone has this exact same problem.
I do remember, however, how they resolved it. They actually ended up filing away the part on the seatstay where the chain rubbed in order to use that last sprocket.
However, I have also read that some people simply just lived without the use of that last sprocket.
I would be hesitant to file away part of my seatstay, personally, but if you have already cold-set the rear triangle, filed away at the rear dropouts, why the heck not? File away the seatstay.
Your best bet is probably to respace your hub by moving a spacer from the left side of the axle to the right side. Or, if it's a 130mm OLD hub, you could add a 5mm spacer to the right to make it 135mm and widen the rear triangle. Presumably you've already widened the rear triangle anyway.
If you do this, you'll have to redish your rear wheel slightly.
I tried using a 7 speed , but ran into the same problem, so I ended up putting a 6 speed on. Works great. The biggest problem was getting the RD to line up right with the rear eyelet, actually had to file the Rd hanger for it to work.
Raleigh20 PugFixie, Merc
Yeah spacers or grinding and adding a fillet weld is pretty much the only way. Or you could get new dropouts fitted that emerge from the inner edges of the stays. I think if you cold-set the stays outwards a bit before attempting to respace the you may find you have enough space. Six speed is probably a better idea though.
Thank you very much for your suggestions. Repeating some of your ideas I also thought about replacing the hub's axle for a 135 mm axle and adding spacers on both sides of the wheel, filling and brazing the seat stay, but in reality I will manage with 6 of the 7 sprockets but I will need a custom cassette. Something like a 19, 17, 15, 14, 13, 12, 11 cassette with a 53, 42 chain wheel set on 451 rims will suit me for the meanwhile.
After all I also had to "invent" the spokes!