On my girlfriends v braked bike I can feel a bow in the rim with a finger, is this enough to need replacing or should I measure it somehow?

Bike is ridden on Sustrans type routes and roads and don't want to spend money and time (rebuilding the wheel) unecessarily; nut equally don't want an exploding wheel.

keppoch.

Everyone has discs now then eh 😉

keppoch

It's hard to tell without a set of calipers and removing the tyre. An experienced mechanic/bike person would be able to guess given a close inspection. Lots of rims now come with wear indicator grooves built in. I'm guessing hers doesn't – or it's worn right past it. A fairly basic wheel will set you back mibbe £40. It is worth it?

When I was running cantis / v brakes the way to tell was:

slight concave to rim = worn

noticable concave to rim = very worn and very easy to dent / crack the rim even without flatting the tyre.

Bear in mind the walls of the rim are only something like 2-3mm thick.

depending on how often you ride and in what conditions, will affect the remaining lifespan of the rim.

I used to get 3 to 4 months from a rear rim, from brand new to sidewall failing, riding regularly in Peak District gritty winters

Straight edge accross the rim braking surface so you can measure the concave wear. More than 0.2mm wear, (use a feeler gauge) and you should think about a replacement.

Hope that helps,

A