Having had a baby and completely losing my appetite for riding on the crazy British roads, my poor road bike has been sat on the wall for 18 months.
There are a couple of gravel trails around here so last week I, perhaps foolishly, decided to put on some fatter tyres and give this whole off road thing a whirl. The new 35mm tyres fit. Just. The clearance is ~1-2mm and the spiky tyre hairs (?) even brush against the front fork. I’ve ridden a couple of times and this hasn’t been a problem, but it is crazy dry here at the moment and I feel like any mud would just clog the whole thing immediately.
I’m therefore questioning whether I should a) put on some 650b wheels to give myself more clearance; or b) accept that I need an actual gravel bike and give up on conversion? I really love my bike so would prefer to keep it, but I don’t know if I’m fooling myself by thinking I can make it a gravel bike.
I think it is probably too rough, though I might get away with it for the next month or two whilst it is warm. As soon as it get wets though, I worry that even 35mm might be too narrow (can you tell I’m new at this off road lark?). The type of race I’m planning is the Wessex Gravel Epic, which says anything around a 38mm is perfect and I have no reason to doubt them!
Got it! In that case get a gravel bike for sure. I’m not the best bike handler, so when a ride suggests at least 38mm…I like to add another 5-10mm!!
You might find a little more clearance with 650b, but I doubt it would be a significant difference and likely not worth the trouble. It would probably really mess with the intended handling of your road bike, too.
My “all road” bike maxes out at 700x40, but that’s also a tight fit, 38s offer more breathing room. But with 650b I can stuff 650x48 in and that’s way more cushy for chunky dirt and rocks. If you like your bike I’d try the 650b route first. Hunt make a nice affordable set in the Hunt X Mason line. New babies aren’t cheap and their stuff takes up a lot of space!
One potential downside of going to 650’s is how it alters the geometry and handling of the bike. That is why bikes like the Cervelo Aspero and others have the flip chips on the forks to accommodate 650’s.
Not saying it won’t work, but just something that needs to be investigated.
The “easiest” solution is to run the 35’s for awhile and see how it goes and then make a decision re: a new bike.
If you see yourself racing, buy a gravel bike. You are right about the need for extra clearance around the tyre, so much, I’d rather run a smaller tyre and have more clearance. For now, instead of the 35s, I’d suggest eg specialized roubaix in 31/33. But longer term, you want to be able to run knobbly tyres, and there isn’t room on your current frame. Not sure if 650b would help - the outside of the 650b tyres is likely close to where a normal road tyre would sit, and if there isn’t more space in the frame, you can’t go wider, even with 650s (you could go taller in tyre, but not sure if those exist)?