SOMA Double Cross Tire Sizing

Posted by Jon Van Lew on August 14, 2015

Tire fit in rear triangle

Googling for “largest tire rear triangle SOMA Double Cross” gives pathetically few results of value. SOMA’s website claims there’s room for a 38c with fender – which is true but seems awful conservative. I guess I can fit something like 45mm tires up in that joint. But since bike tires are about as damned expensive as the tires for my ‘01 Prizm, I hesitate to just dump some money on a guess. And considering there might be others out there like me, I’m providing this post as a reference with some cold, hard numbers.

Right now I’ve got Schwalbe’s 700x35c Delta Cruiser. It fits no problem (the fenders are no longer on here but they always had plenty of clearance).

tire example 1

tire example 2

But when that “35mm tire” is put onto my 18mm Mavic Open rims, it only actually measures about 33.2 mm – fully inflated (to, I don’t know, > 45 psi).

33.2mm tire measurement

This gives plenty of space around the frame. At the seat stay there’s almost 10 mm of spacing on either side of the tire.

seat stay clearance

The least amount of room was near the front derailler assembly. There was about 8~9 mm here

front derailler clearance

Clearance with the chain stay was again almost 10 mm

chain stay clearance

The clearance to the chain stay bridge (is that name of that little guy?) had plenty of clearance, almost 2 cm

chain stay bridge clearance

Based on these measurements, it seems like I could go up to a 45mm tire but conservatively 42mm. Because my front fork is a Surly, and it’s got clearance for days, I might go the route of buying a 45mm and if there’s any rubbing, put that up front and try out the 42mm in back. Regardless, I’ll edit this again/make a new post with sizes and fittings so others can avoid this headache in the future.


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