Clearance for modern wider rims?

DeVlaeminck

My frame is maybe 4-5 years old - it's a Neil Pryde Bura Sl.

Was thinking of buying a new bike but I love the Bura, happy with my fit on it, happy with the way it descends etc etc so thinking instead of spending 3-4k which could go on trips abroad and actually doing stuff just keeping it and getting some deep section carbon clinchers for it to replace the Fulcrum Zeros on it now.

Is there a chance some of the modern wide rims just wont fit the frame? Was looking at a mate's SystemSix last night and his wheels were huge - I know those wheels are designed with that bike in mind but as a rule of thumb is there external rim width beyond which it's best to check first ?

Part of the problem is Neil Pryde is no more so can't ask them. Obviously I could measure the gap between the chain stays but how little clearance is too little? Looking at spending 600-1k (second hand or new - in no rush now autumn is here) and want something minimum 40mm deep but probably more - road racing, fast group rides, usual stuff.

pilot_pete

The other issue is clearance from the seat tube and brake calipers. A larger volume tyre could cause issues depending on how tight the current gap to the seat tube is. Obviously brake calipers will have a maximum width rim and tyre that they will be able to accommodate (assuming it’s not disc). I won’t go there, but this is one of the advantages of disc brakes and wide rims/ tyres. Damn, I said I wouldn’t go there... :roll:

Slightly different issue, but I couldn’t fit a 28mm rear tyre on my Colnago Concept because it rubbed the aero seat tube.

PP

DeVlaeminck

Yes I don't think the tyre height will be an issue with this - I have 25s on with plenty of clearance and most of the stuff I read about tyres and aerodynamics suggests 23s or 25s are optimum even with most modern rims. I'm fine with that - I don't really find comfort to be an issue as is and if I want to ride rougher surfaces I wouldn't be using carbon clinchers - or in fact even my race bike.

timothyw

It's unlikely that even rather wide rims will cause issues so long as used with a correspondingly small tyre (a 23mm tyre will be visibly wider on a modern rim than an old rim - I suspect this is why GP5000s are noticeably smaller than GP4000, as on a modern rim the 25mm gp4000 looks like a 28mm tyre).

Usually the spacing between the stays is that much larger where the actual rim is so it's less likely there will be contact there.

If anything I'd have thought a wider modern rim will actually give more seat tube clearance as the tyre will be slightly less high from the tyre, although having only done a thought experiment on that one I could be wrong.

As for how much space between wheel and frame is safe, generally you want a gap that even a fairly large bit of road gravel can get through... after that it's a question of how much you value the frame and how likely you think it that the wheel might pop a spoke or otherwise come out of true, or how much flex there is in the setup which might cause the wheel to rub.

step83

The Zeros are 21.5 OD 17c ID so I think you can get away going to a 19c or even a 21c ID without too much frame clearance issue as if anything the tyre height will be slightly reduced from the wider rim, your only problem would be brake clearance more so in terms of actually fitting as the caliper yes has a big enough gap, but does the cam open enough to actually get the wheel in?

shirley_basso

also height through the top of the fork. I have a C59 and very tight through there.

DeVlaeminck

Sounds like it wont be an issue then - thanks