Is there a way to guesstimate tire clearance?

[bthomas515]

Been *slowly* lookin for a gravel frame. Found a nicer used ti frame, but the guy has no clue about clearance. It’s apparently a custom build which is somewhere between cross and gravel geo. Is there a measurement I can get to approximate clearance on the rear?

[weisan]

Unless it's a dedicated gravel bike, most cross bikes can't go bigger than 38 or so.

Not such thing as "it's between a cross and a gravel"

It's either gravel...or not. No middle ground.

That's my take and I am sticking to it.

[joosttx]

Originally Posted by weisan

Unless it's a dedicated gravel bike, most cross bikes can't go bigger than 38 or so.

Not such thing as "it's between a cross and a gravel"

It's either gravel...or not. No middle ground.

That's my take and I am sticking to it.

I think to add to what Weisan said. some cross bike cannot go up to 38.

Maybe this could help

https://www.renehersecycles.com/shop...ire-fit-gauge/

[palincss]

Originally Posted by bthomas515

Been *slowly* lookin for a gravel frame. Found a nicer used ti frame, but the guy has no clue about clearance. It’s apparently a custom build which is somewhere between cross and gravel geo. Is there a measurement I can get to approximate clearance on the rear?

Tire Fit Gauge

$25.00

How wide a tire can I fit on this bike? It’s a common question, especially when converting a bike from one wheel size to another. Hahn Rossman’s Tire Fit Gauge eliminates the guesswork: One end hooks over an axle placed in the dropouts. The other end has slots for three wheel sizes: 559 mm (26”), 584 mm (650B) and 622 mm (700C). Discs that represent different tire widths fit into the slots: 23, 34, 38, 42, 48 and 54 mm. Slide a disc into the slot for a rim diameter, and rotate the gauge around the axle to check the clearances for this tire size all around the frame.

Designed for 13 mm dummy axles in frame jigs, the Tire Fit Gauge can be used with other axles if their diameter is increased with a few layers of tape.

The gauge is laser-cut from plastic. Remove protective cover before you use it.
https://www.renehersecycles.com/shop...ire-fit-gauge/

[GoldenUnicorn]

Just keep in mind that the tire fit gauge will still only be an approximate estimate. There is significant variation between one companies 32mm and another companies. To further complicate it, it will change depending on what your rim width is.

I have a gravel bike, and because it was kinda 1st gen, the largest tire I can run is a 700x38. Which is pretty decent sized. But what I do instead, is run a 650 tire. That way I can run a 45c tire without issue, and sacrifice very little with the 650. For myself, a 650 tire and rim also fits much easier in a S&S travel case.

[false_Aest]

I feel like this is somewhat easy to estimate.

Look up the circumference of a few tires:
700x40
700x35
700x32

Whatever you want.

C / pi = D

D/2 = R

Take your R + subtract 1/2 of the tire width to estimate the widest part of the tire. Then measure from the center of the drop out, along the CS to that point. With calipers measure the inside of the CS.

e.g.

700x40 = 2200 circumference (according to the Cateye tire chart)

2200 / PI = 700.28
700.28 / 2 = 350
350 - (40/2) = 330

So if you measure the gap between CS at 330mm from the center of the drop out and it's < say 50mm, you probably shouldn't put a 700x40 in there. But a 700x38 will probably fit nicely.

[Ken Robb]

can the seller install a wheel with a tire of any size in the frame so you can estimate max clearance?

[sparky33]

Originally Posted by Ken Robb

can the seller install a wheel with a tire of any size in the frame so you can estimate max clearance?

Agreed.

This basically comes down to the seller putting in some sensible effort. Pick a wheel and tire. Measure the tire, measure the available clearance to each chainstay and to the seat tube. That will inform you on how big a tire will fit.

Pro tip, I use my metric allen wrenches to accurately measure the clearance gap. If an 8mm allen fills the gap, you have 8mm to of clearance to work with.

[oldpotatoe]

Originally Posted by bthomas515

Been *slowly* lookin for a gravel frame. Found a nicer used ti frame, but the guy has no clue about clearance. It’s apparently a custom build which is somewhere between cross and gravel geo. Is there a measurement I can get to approximate clearance on the rear?

There are tools but the

It’s apparently a custom build which is somewhere between cross and gravel geo

YUP

No such thing as "it's between a cross and a gravel"
It's either gravel...or not. No middle ground.

NOPE, not for geometry.

Since it's custom VERY easy to have a compromised in GEOMETRY..so yes, there IS such a thing as 'somewhere between cross and gravel GEO'

[avalonracing]

Originally Posted by weisan

Not such thing as "it's between a cross and a gravel"

It's either gravel...or not. No middle ground.

I once heard about a group of guys who tried riding their cross bikes on a half-mile section of a smooth gravel road. There were no survivors.

[oldpotatoe]

Originally Posted by avalonracing

I once heard about a group of guys who tried riding their cross bikes on a half-mile section of a smooth gravel road. There were no survivors.

Surprised they weren't arrested first by the 'purpose driven bike' police..

I heard one even had(horrors!!), canti brakes...