Originally Posted by
dsaul
I noticed that frame has rocker dropouts, do you have them adjusted all the way back? It looks like you could get a few more millimeters per side from more dimpling, but not enough to get a 42 in there. If it were mine and I could find a way to fixture it on the mill, I would cut out a section of the stays with a hole saw and weld in a section of heavy walled tube. It could also be done without the hole saw, but would definitely take longer to get a nice fit for welding in the section of tube.
I have the rockers about half-way back, but I don't think that would help. the drivetrain is singlespeed, so I can't push the wheel back more with the current gearing. I tried a few other gearing combos and realized it's a moot point because the dimples in the frame are tapered in such a way that they the most clearance is available where the axle is closest to the bottom bracket. if I take the chain off and loosen the dropouts so the swing freely through their path, the clearance gets worse as I swing them back. that's counter-intuitive, but the chainstays were inexplicably welded at the bottom bracket so close together that there's more tire clearance because of the existing dimples than there is where the angle of the stays diverges. there was no apparent need for this design choice as there's an absurd amount of chainring clearance. weird.
The method you describe is what I was hoping someone could do: cut out a segment of the inside of the chainstays and weld a section of another tube. probably not cost-effective for someone with that kind of skill, but I was hoping to find someone local who could actually give me a quote.
at this point, the bike is becoming less and less fun for me, but I can't get something else. first world problems!