Val — I already lengthened the chainstays 1cm to make life easier. Not sure I want to go 2cm. Part of this is the challenge, life isn”t fun without some good challenges.

I wish I had titled this post “Rear tire clearance is harder than it looks”. Guess I could change it. The goal was more to show some of the challenges in building fat tired road bikes rather than complaining.

You can also intent the chainstay as Alistair did on his 650B bike:
http://www.flickr.com/photos/duncancycles/2689389729/in/set-72157604494651833/

Most traditional steel frames have straight chainstays which aren”t manipulated this way. You don”t need to when the frame is built for tires up to around 32mm. It’’s when you get into 40-60mm tires that things get more challenging.

Longer chainstays make this easier (because the tire is farther from the bottom bracket) and shorter ones make it more difficult.

Mountain bikes typically have smaller chainrings and wider cranks which also makes this easier. It’’s not impossible to nail it and get fat tires, skinny cranks, and large chainrings, but it does take more thinking and measuring. It’’s these small things that make the difference between a good frame and a great one in my eyes.