Technical > Wheels, Tyres and Brakes

A319 rims - are these worn?

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cpk:
I bought my club tour 2nd/3rd hand and I've been doing some reading and possibly thinking my rims are worn but I might be being a bit cautious - the consequences of it failing during a ride scare me a bit  :).  I've got no idea of miles ridden. 

The only thing that has worn on the bike are pads (not sure how many sets it's had though!), bottom bracket completely shot (BB-SM51 so suspect original),  and the Pasela tyres that I suspect were original. Badly perished but still a fair bit of tread.  From that I suspect it's not done 10's of thousands.

Can anyone cast an expert opinion on the pic of the rear rim below.  There is light visible on both rear and front but rear is worse and that is the picture.  Braking performance is a bit rubbish despite new shimano blocks, both rims are badly scored.


https://ibb.co/i8WCBx

geocycle:
 Rims often become concave and/or bow outward when they get really thin.  I've not had one explode on me but I have seen one collapse over a few rides. There are calipers available to check thickness if you want reassurance.  If these are original tyres I would expect the rims to outlive them by quite a bit. You mention shimano blocks which I have always found very prone to chewing rims and picking up shards of aluminium.  I generally prefer a softer compound. Personally I'd be prepared to risk it unless you are planning a major trip (disclaimer -impossible for any of us to tell from pictures with any confidence).

cpk:
Thanks for the reply.

I have decided to change my blocks and ditch the Shimanos, I was riding an old shopping bike at the weekend and found the brakes to be far more effective than my thorn.  I'm changing the Shimanos to Aztecs as I think that is my only option on the CX-50s.  It was looking at my blocks that got me thinking about the rims, they're not perfectly true and I'm finding it tricky to get good brake performance on the rear.

I'll look into the caliper check, it would give me peace of mind at the very least.

martinf:
There's a discussion about rim wear here :

https://forum.cyclinguk.org/viewtopic.php?f=5&t=18238

with a photo near the bottom of the page of a tool made from an old spoke that lets you measure rim wall thickness with an ordinary vernier calliper.

I used a bent spoke like this to measure the rear rim on my old 650B utility bike, which picked up a lot of wear this winter due to braking during wet and muddy survey work. It's an old rim, with no wear indicator.

Contrary to my expectations the rim is still OK (about 1.6 mm thickness), so I have just noted to check again at regular intervals.

martinf:

--- Quote from: cpk on April 24, 2018, 10:06:48 am ---Braking performance is a bit rubbish despite new shimano blocks, both rims are badly scored.

--- End quote ---

Shimano blocks are hard on rims. I don't know why - Shimano rims don't seem to be very common, so it doesn't seem likely they do it to increase rim sales.

On the Raven Tour 390 Step Through I recently built up, I noticed the rims were already getting marked after just 2 test rides, so I removed the nearly-new Shimano pads and fitted Kool Stop Salmon instead. In my experience these cause far less rim wear as well as giving good wet-weather braking.

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