Wheel rims

Fnaar

Smutmaster General
Location
Thumberland
Have been reading a bit here and there about wheel rims and wearing them out... I bought my roadie a few years ago now (might be about 5, can't really remember)... It didn't have any wear-markings (pretty sure about that, though I have to say I wasn't looking for them either)... it's an increasing number of miles each year (last yr prob 1500-1800) and I've managed to scare myself silly about the rim collapsing while I'm riding along... :smile:
I guess I brake an average amount, just wondering how long they last. They are 'no-name' wheels that came with the bike, all reasonable spec and had no serious trouble with it (apart from gears, but that was my fault for riding over a branch).
 

MartinC

Über Member
Location
Cheltenham
You can form an opinion on how worn they are by looking and feeling to see how concave the braking surface has been worn. This obviously needs some knowledge of how thick the rims were originally and how thick you still want them to be. You can measure them by taking the tyre and tub off and using a vernier guage to measure the remaining thickness of the rim. You'll need to put some packing of a known width (e.g. a cut of piece of plain 14 guage spoke - 2mm) on either side of the rim to cater for the hook on the inside and the wear on the outside. You then need to know how thin the manufacturer (or you) likes them to be. Google around to find opinions on this.

Trying to judge the wear by the mileage doesn't help - it'll depend on the type of brake blocks you use, your riding style and the road conditions.

Some people test their rims now and again by inflating the tyres to way beyond theur normal pressures to see if they can take it without any splitting. I've never been really convinced by this but it's better than nothing. If you do this be careful and make sure your eyes are protected from anything that blows off.

Obviously you understand the dangers of worn rims. Don't let anyone fool you into thinking it doesn't matter.
 

PpPete

Guru
Location
Chandler's Ford
MartinC said:
You can form an opinion on how worn they are by looking and feeling to see how concave the braking surface has been worn. This obviously needs some knowledge of how thick the rims were originally and how thick you still want them to be. You can measure them by taking the tyre and tub off and using a vernier guage to measure the remaining thickness of the rim. You'll need to put some packing of a known width (e.g. a cut of piece of plain 14 guage spoke - 2mm) on either side of the rim to cater for the hook on the inside and the wear on the outside. You then need to know how thin the manufacturer (or you) likes them to be. Google around to find opinions on this.

Trying to judge the wear by the mileage doesn't help - it'll depend on the type of brake blocks you use, your riding style and the road conditions.

Some people test their rims now and again by inflating the tyres to way beyond theur normal pressures to see if they can take it without any splitting. I've never been really convinced by this but it's better than nothing. If you do this be careful and make sure your eyes are protected from anything that blows off.

Obviously you understand the dangers of worn rims. Don't let anyone fool you into thinking it doesn't matter.

Get a proper rim gauge rather than trying to pack out a vernier. About 1/10th the cost of new rim. Don't forget to measure at several points around the rim. As a rule of thumb I wouldn't go below 1 mm thickness unless specific info to the contrary from manufacturer.

Just imagine - rolling downhill quite happily at speeds of 30 mph or more .... and all our weight (considerable in my case) ... just relying on 1 mm thickness of aluminium not buckling !
 
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