Originally Posted by
Marcus_Ti
You have to lengthen the stays anyway--for tire clearance at the BB. If you stick to 700C wheels. Which is why 650B conversions are taking off, lowering the high center of gravity and often finding more tire clearance.
By the time you're done making all the tweaks, you end up with a dropbar 29er MTB...rather than road/CX/touring geometry that can take big tires. Not that there's anything wrong with that.
Look at all the engineering that went it Cur've GMX clearing a 60mm tire:
https://www.curvecycling.com.au/prod...-monster-cross
The chainstays (length) and yolk are very similar to my Carver, but they bent the seat tube, made a CF MTB fork...and top-tube routed all the cabling. They were able to make 68mm roadie std BB/cranks work, although for a bike that sees such offroad duties you probably want MTB clutched RDs. And for 60mm tires a 50T high gear is way too high, Heck even a 46T high gear is probably still barely usable.
Yeah that Cur've has some trick engineering but you originally talked about fitting 700x45mm tyres being hard. Making 700x45-50mm tyres fit with a 68mm BB is easy if you lengthen the chainstays a bit compared to a road bike. Around 440mm, if possible a bit of dimpling, that's all you need (Salsa Journeyman). At least in my opinion that alone doesn't turn a bike into a drop bar MTB. Of course every bike reviewer would point out that the bike is "not as flickable" or some other nonsense crap.
