Hi there,
I'm in the process of converting a 1980s Holdsworth Avanti road bike to a fixie. It's taken me a while to get here, but I'm on the home straight, all I need to do is get the right bottom bracket/chainset combo for perfect chainline.
My girlfriend kindly gave me her flip flop rear wheel, which I've put in my frame (spacing is approx. 127mm - I imagine it was originally 126mm but the guy I bought it off had forced in a freewheel with too many sprockets and probably stretched it out over time). The hub on the rear wheel is 120mm, so I bought two 3mm spacers to go either side of the hub and it seems to sit fine.
I've measured my rear chainline, which is approx. 41.5mm, by measuring the distance from sprocket to inside of dropout (21.94mm), and subtracting this from half of 127 (63.5).
The bottom bracket currently on my bike is the one the previous owner installed. It's an SKF Thun with strange plastic lock rings, which I plan to replace. Its spindle is 119mm. I've borrowed a friend's Miche Xpress chain set just to get an idea of what the chainline looks like (this is my first conversion) and installed that. Currently, front chainline is 46mm.
So, I'm out by 4mm, which is obviously too much. By my calculations, I need a bottom bracket with a 111mm spindle (or something close to that) in order to shave 4mm off the drive side (obviously this assumes the spindle is symmetrical, which it may not be) and get the front and rear chainline the same.
Having said that, I've ridden it a little bit and despite the chainline being off it seemed OK. Chain didn't slip or threaten to fall off or anything. Didn't really push it though.
I'm thinking of also getting a Miche Xpress chain set, just to eliminate one of the variables, and get a suitable bottom bracket. If anyone could point out where I've gone wrong or something I've overlooked before I go ahead and get a bottom bracket, I would really appreciate it.
Reading these forums and others has got me this far and it would be great if your advice could give me that final push! Thanks.
