I have a Ragley Trig which is rated for 700x40 tyres at the back and that's what I'm currently running (Maxxis Receptors).
My main bike (which I ride rather more) is 29x2.0 and I'm finding the difference in width (which isn't huge) noticeable.
There's probably a good 4mm between the edge of the tyres & the chain stays & chain stay bridge but the Receptors have very shallow side knobs. I was wondering whether I could squeak in a 45mm tyre in (I appreciate that that will depend on design/side knobs & the foibles of different manufacturers' measuring).
Generally I don't ride muddy stuff but there's always times when I get caught out and as someone who's financially challenged I like my frames to last (I don't want to munch through the chain stays).
Generally speaking, speaking, what's a sensible amount of clearance between a tyre & chain stay?
I have a sneaky suspicion that 45mm might be pushing it (although I have come across a few 42mm tyres) so it might make more sense to stick with 40mm at the back & put a 45mm or 50mm tyre at the front (the fork has plenty of clearance).
At 4mm, if say you're at your limit. Keep in mind you're checking static clearance but stuff does move and flex while riding. I'd not want to go any larger if it were mineÂ
Mine came with 47mm tyres. I've now fitted nominally 50mm Pirellis Cinturato Gravel M and they are tight at 4mm either side; you can see where mud has scuffed the paint.
The Pirellis measure 52mm on a 19mm rim, so you might find that a different tyre/rim gives you more/less clearance for the same nominal width. I'll try the 45mm option next time I'm buying
Had another look & I think I've been a bit conservative, it's probably closer to 6-7mm but I think I'll stick at 700x40 for the rear. When it comes time to replace them I'll try something wider at the front.
Generally speaking, speaking, what's a sensible amount of clearance between a tyre & chain stay?
6mm or more for anything that goes off road
My 45mm Caracal Race measures ~46.5mm on the 21mm internal rim width wheels, leaving ~5mm clearance each side. GT officially say 47mm tyre max, I wouldn't risk anything much bigger and that's on ~95% tarmac rides.
Apparently many 40mm Caracal Race owners on modern rims 20mm+ are finding them 41-42mm measured.
I've got about 2mm of clearance at the rear on my cyclocross bike when I jam 40mm tyres in there.
Unsurprisingly I quickly wore through the paint and may even have worn into the aluminium. I helitaped it and don't appear to have done any more damage, ran it for the rest of the winter, and then another winter this year 😎
The tyre looks a bit thready around the sidewall so perhaps it is scuffing more than I realise.
It does depend a bit on the tyre model and your rim's internal width. Some tyres also stretch a bit more than others so erring on the conservative side is sensible. Schwalbe and Pirelli seem true to size to me (on 25mm internal rims anyway), Hutchinson maybe a bit bigger (although I have those on 32mm internal rims, they're 45mm but measure nearly 49mm). I've read Vittoria & Maxxis can be under-sized but haven't used them myself.
My current Gravel bike is listed as having 45mm clearance, I've got a 2" (52mm) MTB tyre in the front and an 47mm Gravel tyre in the rear.
The only real point of concern is the seat stay clearance where it's maybe 5mm each side, a bit of wheel deflection or a big enough stone caught on a shoulder knob might cause an issue, but it's not a fancy bike, if it were a posh carbon thing I'd adhere to the manufacturer's recommendation.Â
My CX bike currently has 700x40 tyres again listed max is ~35mm IIRC and while they clear but I'd not use these tyres year round, deepest darkest winter slop I have a pair of 31mm tyres, harsher ride and more risk of pinching a sidewall (IME) but excellent mud clearance...Â
Helicopter tape on inside of frame and forks will help prevent damage
I've just put a 45mm Panaracer Gravelking X1 on the rear of my Trig (DT Swiss G1800 rim). It's not so tight that I'm concerned about clearance. Can try and measure what room there is later if needed.
Have also put the 50mm version up front which still as loads of clearance in that fork.
I think there's a legal limit that bike makers have to follow when selling a bike. I think it's 5-6mm of clearance.
My Digger came with 45mm Bites. I've moved to 47mm Pathfinders and I can still get my finger between the tyre and the frame.Â
Mine has 42mm clearance - it was sold as quite the race end of the gravel spectrum rather than the gnarr end and the bike is only a year old but it's noticeable how quickly manufacturers of even the mid/high-end race gravel are moving to 50mm minimum.
Mine has 40mm in there at the moment and so far it's not proven an issue. I think 42 would be quite a squeeze and 45 would be well into frame damage territory.
