How much tire clearance do I really need for gravel?

So new bike day for me and I’m trying to run the biggest tires I can in the new bike for optimal traction (and to stop me falling over and breaking my body any more :slight_smile: )

It seems my new bike has lots of clearance either side but the issue is around the top (the radius of the wheel) where it is close to the seat tube. With the wheel / tire combo i want to run I only have about 2mm which seems tight to me. Going to fling some 3M tape in there in case a stone gets stuck to prevent damage to the frame but I’m more concerned about jamming the whole wheel up and causing a crash.

I’m thinking that bigger sones rocks would get knocked off anyway and maybe less clearance might actually be safer in that regards :man_shrugging:

What are peoples thoughts and anyone had issues running with less clearance than ideal?

Also I won’t be riding this bike in much or mud. This is the nice bike :smiley:

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I had about 2mm clearance for a while. It didn’t rub in bike stand, but when pedalled hard, was some flex and rub at chain stay. Not sure if you will have same issue up top…

Jim.

Given your luck that seems really tight, but I’m not sure if there is a standard.

On the chainstays watch wheel flex, if you pull from the side at the tightest point and it doesn’t rub the frame that is a good start but wheels flex more under sprint loads. I bent a alu chainstay once with a stone jamming between the wheel with and good clearance, no idea when but the evidence was there.

As for your clearance on the seat tube, the amount of gravel pickup is going to depend on the tire. I’d be less concerned about frame damage and more of sudden wheel lock up. My S5 has ~6mm clearance and it seems they designed the frame with the minimum amount available for the road. I’d want more on gravel a lot more with any mud.

There does seem to be quite a lot of space left / right it is just in the cutout for around the seat tube vertically that there is limited space.

Yes, it is the wheel lockup I’m worried about. Going down is painful (and I’m done with broken bones!). I’m trying to weigh up the extra stability of width vs the likelihood of a lockup happening.

I did P2A 2 yrs ago on 38mm tires, the max for the frame. Both the front and rear wheels locked up and I had to spend a lot of effort to clear them. Admittedly P2A is extreme but I would not recommend riding with minimal clearance.

I think my p2a days are over @JimDaley :slightly_smiling_face: but I do have a second gravel bike for bad weather if I do want to ride in the mud ( which is pretty unlikely) This is the good weather bike.

I too have had to clear mud from a bike, made it hard to pedal but didn’t lock the rear. From my googling there seems lots of talk of people being worried about locking the rear wheel with a rock but I haven’t found an actual instance of it happening. Im wondering if it is a theoretical risk rather than a real one. Anyone actually had it happen to them or seen someone else go down because of it? Damage from rocks seems documented though.

Stone damage is an inevitability with gravel riding. I have had a few chips on the frames over the years and have a good sized dent in one of my wheels from a stone being shot off another riders wheel. Never seen or heard of a rock getting jammed and causing a fall or damage but the smaller the clearance the higher the risk seems logical.

What does your new bike manufacturer publish as the maximum tire size? I would follow that.

(I think I would seek a medium width, to balance weight and ride feel, and pick what seemed the best tread pattern to address traction. :slight_smile:

Also note most tires are “unround” - so there will be some tires that’s are fatter but less tall - see if you can source those (bicycle rolling resistance has many measurements).
My current Challenge getaways are kinda the opposite - they seem kinda tall for a 40mm

Did a lot of looking at heights of tires and it seems like the tire is either tall or not irrespective of width ( just some are designed that way).

It seems that Schwalbe tires are the lowest height vs width but it is going to be maybe a couple of mm extra clearance.

I put the stock tires and wheels on just to see how close they are and to be honest they are pretty tight too. So I’m going to stick with the wider once in my nice wheels for the sake of a mm of extra clearance. Went for a short shakedown with the new bike today and no issues or jamming up despite it being a little damp out.

I’ll let you if I run into issues. Thanks for help everyone!




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It’s gonna be great just to get out there again :sunglasses:

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