Author Topic: A319 rims - are these worn?  (Read 173 times)

cpk

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A319 rims - are these worn?
« on: April 24, 2018, 10:06:48 AM »
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
« Last Edit: April 24, 2018, 10:08:55 AM by cpk »

geocycle

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Re: A319 rims - are these worn?
« Reply #1 on: April 24, 2018, 11:41:20 AM »
 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

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Re: A319 rims - are these worn?
« Reply #2 on: April 24, 2018, 11:51:58 AM »
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

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Re: A319 rims - are these worn?
« Reply #3 on: April 24, 2018, 12:40:58 PM »
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

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Re: A319 rims - are these worn?
« Reply #4 on: April 24, 2018, 12:47:28 PM »
Braking performance is a bit rubbish despite new shimano blocks, both rims are badly scored.

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.

PH

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Re: A319 rims - are these worn?
« Reply #5 on: April 24, 2018, 01:12:10 PM »
it's possible that your A319s have a wear indicator, though it's not obvious without knowing where to look for it
Quote
Process: The inside of the braking surface of the rim is machined on both of the wings of the rim.
Principle:
When there is too much wear on the rim, a little hole appears on each of the 2 braking surfaces of the rim. Depending on the adjustment of the brake pads, it is possible
for the wear indicator to appear on only one of the 2 braking surfaces. In any case, the appearance of the wear indicator on at least one of the 2 braking surfaces
means that the sidewalls are too thin, and it could be dangerous to continue to use the rim. It should be replaced as soon as possible.
The position of the wear indicator is marked by 2 yellow arrows on the stickers on the rim, opposite the valve hole.
Refer to the chart on the previous page to find out which rims offer this internal wear indicator.
https://tech.mavic.com/tech-mavic/technical_manual/data/docs/products/2_119.pdf

I've seen or heard of a few go, if it's a box section rim then some designs will hold together even when it's worn right through, that's not to say it's advisable to let it get so bad, but the failure mode isn't catastrophic.  On any rim, I'd be more inclined to accept more wear on the rear than front, it's likely to be different consequences from the same failure. 

Getting the best from your brakes is a whole different subject, but I agree with those suggesting there are better blocks than Shimano, both for braking and rim life.

cpk

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Re: A319 rims - are these worn?
« Reply #6 on: April 24, 2018, 01:31:08 PM »
Thanks for the PDF link, that's really useful.

I'll have a look for the indicators and see what I can find.  I did wonder if they existed but assumed because mine are 9ish years old that they maybe pre-dated the wear indicators.

cpk

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Re: A319 rims - are these worn?
« Reply #7 on: April 24, 2018, 02:35:24 PM »
I'm not sure what vintage my rims are but they don't have any yellow arrows as expected from the wear and tear indicator.  Just some arrows indicating the number of spokes.  No holes found.

Anyway, I removed the tyre and got a caliper on it supported by coat hanger on either side.  Remaining rim thickness is in excess of 1mm so I'm confident they've got some life left in them. 

New pads on order so hopefully they'll keep me going for a few more years yet.

Thanks for all the help.