kawaray

Hi,


I have a vintage bike frame by Terry Osell who was apparently active in Minneapolis some years ago. I purchased the frame with a fork off of eBay, and it was advertised as a "touring frame." I am trying to determine the size of wheels that is most appropriate for the frame. The frame is small with 50 cm (C-C) seat tube, and has bosses for brakes. These bosses are each accompanied by 1 hole toward the inside of the frame, so I am thinking that they are "mafac bosses." They are also positioned relatively low, so they sit ~24 mm below the rims of 700c wheels.

I was able to build the frame with 700c wheels using cantilever brakes. However, clearance for tires (700x25) are small, and given that this might be a "touring" frame, I was wondering if I was supposed to use smaller-sized wheels (26 inches or 650b) to accommodate wider tires and greater clearance that should allow use of fenders. Yet, I don't think I can use cantilever with smaller-sized wheels. Does anyone have any thoughts? I even considered if I could use center pull brakes, but it seems that bosses for center pull brakes should be positioned much higher.

machinist42

RiddleOfSteel

Lovely color on that frame! It looks like it was designed for 700C wheels as the canti (cantilever brake) posts are positioned at a typical distance below the brake track's centerline. Why so little tire (and fender) clearance exists is a mystery to me as well. I have the same posts on my '85 Trek 620, and it uses Shimano MC70 cantis.

How long are the chain stays? From the repeating photos, I can see the front derailleur cage's position relative to the rear rim. Looks pretty short, like on the order of 41-41.5cm. If so (or very close), then it may not be a touring bike, but a road/race-geometry'd bike with some flair (canti brakes instead of side pulls).

kawaray

Hi,

Thanks for your inputs. That is great to hear that you are also thinking that the frame should be built with 700c wheels (I don't have an easy access to wheels of other sizes). I will measure the chain stay once I get a chance to confirm what you suggested (sorry about repeating photos!). I was really hoping to use it with fenders, but I might have to let that idea go. Still, I like the quality and the color of the frame, so it is all good! Thanks!

nlerner

I've encountered cyclocross frames that took 700c wheels, canti brakes, and had fairly narrow clearance for tires. They usually had high bottom brackets, too, which I wasn't crazy about.

tcs

Doing a period resto? It's a sport touring bike with 25mm tires.

Going to be a rider? Promax Brake Boss Adapters. Drop the brake C/L 16mm.

Hmm. (622mm - 590mm)/2 = 16mm

T-Mar

Based on those measurements, it's deigned for 700C. Nominal pivot to centre-line of brake shoe distance for most C&V cantilevers is typically in the 23-25mm range. Most C&V cantilevers don't have a very large pad adjustment range. I don't think there are any small wheel sises that would work. 650B rims would have the bead seat positioned just about even with the cantilever stud.

kawaray

Thanks for your inputs. 700C and cantilevers sound like the way to go. I was suspecting that this is the case, but since the bosses did not have 3 holes (more typical for catilever bosses, correct?), I was having a second thought. I did look into the Promax's adapter, but it seems to require removable bosses for it to work...