Bought a down hill bike a few months ago and finally getting round to using it this weekend at an uplift at fort bill.

During close inspection I’ve found a couple of worrying cracks in the rear rim, one around a spoke and one round the valve hole. Have removed the rim tape and it looks ok on the other side, but its definitely cracked.

he wheel will be replaced before my Alpine trip in a month, but will it last a day of riding at the weekend. If not anywhere in Edinbugh that will be able to build a wheel at short notice?

Pics below, although quite hard to make out cracks

Hard to make out?! That’s ****.

I’d go for a bimble on it, wouldn’t want to ride DH on it, but they’ve not just appeared, so it’ll probably be fine.

Mine was like that for quite a while. They grow over time so it’s been like for a while. Unlikely to suddenly explode but it will fail one day you just don’t know which day.

what rims are they?

so how hard will it be to lace an identical rim onto the hub,, can I use the existing spokes. The issue isnt the cost of repair, its finding a bike shop that can do it this week, which in edinburgh is probably unlikely.

I’m asuming taping a new rim next to the old one and just switching the spokes will be eady enough, but how hard is it to get it dished and true. Neever done it before?

identical new rim and its easy enough – making a spoke driver thingy out of a flat head screwdriver is worth the time though – especially if you do it again……dont drop a nipple into the rim – they can be a right pain to get out

Very easy to change a rim. As you say, tape the new one to the old one (noting that the valve needs to be aligned) and swap one spoke at a time. If you fit the nipples carefully there’s not much to it. Thread a nipple until the thread disappears. Once you’ve done them all go round again tightening each one a single turn. Then again. Repeat until they start to go tight. By now the wheel should be almost true and fairly tight. Now just do a final true and dish.

given the timing and the fact the bearings on the hub appear a little goosed as well I thought sod it and found myself a nukeproof generator wheel on CRC for 115 quid. Works out about the same as a rebuild by the time I bought a rim, new bearings and paid for a rebuild (assuming they’d probably want to use new spokes)

I can keep the old one for an emergency

Thanks for the advice

what rims are they?

I guess mavic, 721?