Q. I know that there are various aluminium alloys used in the manufacture of bicycle frames but what about wheel rims? Some rims seem to wear faster than others and I have heard of some that only last the life of a tyre!
At the start of a recent audax ride, a friend and I compared the apparent excessive wear on our rear wheels. Then, during the ride, my friend had a large section of his rim blow off - luckily just before a steep descent! My question is: are there different grades of aluminium used in wheel rims and is there a 'wear comparison' chart for different makes of rim?
Dave Galle, email
A. The braking surface of a worn rim will take on a convex appearance and in extreme cases the wall can wear through to the point that the inner tube pokes through it. Sections of the rim can also become detached from the rest of the wheel causing the tyre to bulge sideways. Thankfully the degree of wear present on a rim is easier to gauge these days, with many rims having a wear-line in the side to indicate the degree of service life left in them; when the line wears out, the rim should be replaced.
No one grade of aluminium alloy is harder than another and, in my experience, Mavic rims have a similar life expectancy to other well-known brands such as Sun, Ambrosio and Alex. That said, if you are both 'doing the miles' then I recommend that you consider ceramic-coated versions of the Mavic Open Pro because I've found that this rim provides a much longer service and indeed stronger braking performance than one with a normal braking surface. Mavic Open Pro Ceramic rims costs £74.50 each - visit Chicken at www.chickencycles.co.uk.