tire clearance

[Dead Man]

gentlehumen,

did a search for "tire clearance" and scanned the first few pages.. i know this topic has surely been covered in extreme detail here on PL, but from my phone and with my search fu i bailed and am just gonna post...

i bought an old steel trek frame to start building up a new bike after my last'n got pilfered. given the vintage, i assumed id be riding 23s or maybe 25s at the most, but i just calipered the stays and ive got 35mm of spacing out back. the fork has a million miles of clearance.. so now im thinking 28s are a strong possibility. pleasant surprise! unless im missing something?

how much spacing translates to how much tire you can get back there? in the past ive just always had an assortment of wheels and tires and could just slam something on a new frame to see what itll take, but these days im living light and the one bike that absconded was the entirety of my bike parts collection.. nothing to reference.

not sure the rim width yet, but im going for full vintage on this bike, which almost certainly will mean narrow rims.. so i suppose thats gonna ballon my tires a bit eh?

thanks my dawgs

[eddief]

what will fit under the fork crown or under the rear brake bridge or behind chainstay bridge...when the brakes are installed.

[pbarry]

double post.

[Dead Man]

what will fit under the fork crown or under the rear brake bridge or behind chainstay bridge.

mmm.. not issues i was expecting. ive never had crown or bridge compatibility with bikes before - i take it this is a potential issue with older steel frames then?

[pbarry]

I've usually just measured and rolled the dice, but this is interesting:
https://www.roadbikerider.com/hahn-rossmans-ingenious-tire-clearance-checker/

This will give you the diameter of the wheel with tire:
https://www.bikecalc.com/wheel_size_math

[eddief]

there are a few variables. axle to crown dimension, location of brake bolt hole, and the clearance associated with whichever brakes you install.

here's a blog post on medium reach brakes as an example. same bike, different brakes, different amounts of clearance.

https://blackmtncycles.com/clearance-pt-ii-road-frames/

mmm.. not issues i was expecting. ive never had crown or bridge compatibility with bikes before - i take it this is a potential issue with older steel frames then?

[stien]

I’m sure one of us can tell you at what distance a 28 is fattest from the center of the axle. That’ll give you a very good idea. I can do it tomorrow if nobody beats me to it. 35 in the right place will be great for 28s. Or if you’re measuring at the crown of fork and chainstay bridge, you’re golden unless the height is an issue. Sorry to hear about your last bike.

[ColonelJLloyd]

Provide some more details. What model and year? Is it designed around short or medium reach calipers?

not sure the rim width yet, but im going for full vintage on this bike, which almost certainly will mean narrow rims.. so i suppose thats gonna ballon my tires a bit eh?

You have the correlation to internal rim width backward.

[ColonelJLloyd]

I’m sure one of us can tell you at what distance a 28 is fattest from the center of the axle.

I think the short math would be the rim BSD plus the tire width divided by 2. (622+28)/2=325mm