I just realized the BOB trailers are spec'd for 126.5mm minimum dropout spacing, but I was hoping to use it on a 120mm dropout (vintage Stumpjumper). Is there a secure way around this via a spacer or something or should I just cave in and spread my stays? Anyone use a BOB with 120mm dropouts?
I would put a 5mm spacer on the outside of each dropout to fill any gap in the bob's yoke. That should work fine, will be the easiest solution and will prevent you from having to respace your vintage frame.
Respacing a steel frame is easy enough, but afterwards you will have to either:
1) replace your rear hub (with a non vintage part, if that matters to you- it might matter to me, depending on the year of the stumpy),
2) add spacers to the existing hub- which will weaken the rear wheel by increasing the chances of bent or broken axles (longer torque-arm between the bearing races and the dropout).
Even if you want to do option 1 and upgrade from vintage to modern hub, you will have to respace the frame from 120 - 135mm. This is a large spread, and it means you will certainly have to re-align the dropout faces, as they will no longer be paralell- so plan to find an LBS or framebuilder with the proper park tool to do this. The second problem that might occur with such a big respacing is that the brazing or welding of the brake bridge or chainstay bridge can pop, which is fixable (by a framebuilder or experienced metalworker), but a royal pain. If you do respace the frame, use fiberglass strapping tape to take the stress off these two points of the rear triangle before doing the levering.
Thanks for the info. I'm thinking to use the components I want I will need to respace the frame. I don't care about leaving it original at this point, I just want something that will work and I can find parts for. I'm going to create a separate thread just about the Stumpy project, thanks again for the help if I go 120 I'll use the spacer idea... Oh and Boondock thanks for the link I hadn't seen that before...