Spectacular rim split

robjh

Legendary Member
This happened to me out on a ride today
20141214 split rim (1).JPG

The horizontal strip across the middle of the picture is the edge of the rim. It sliced an 8-inch gash through the inner tube
20141214 split rim (7).JPG


I had a few minutes warning that something was up, as the back wheel developed a knocking sound, which I traced to a slight bulge on the lip of the rim, and there was an earlier clue if only I'd recognised it, as my braking began to catch on one side.

Luckily all was OK in the end, and the kindly Mrs rjh was on hand to come out and pick me and bike up.

I have a spare rim and am now weighing up the benefits of fitting it myself vs. a new wheel.
 

screenman

Legendary Member
Did the wear indicators give a clue?
 
OP
robjh

robjh

Legendary Member
Did the wear indicators give a clue?
It's a Mavic Open Pro, and despite looking at the rim and searching on line I still can't be sure that it has any.

Again, had I realised what I was looking at there were earlier clues. On replacing a tyre recently I noticed that the rim had a more pronounced lip on one side than the other, but consistent all the way round, and was still running fine ( I was looking at wheel true and how the brake pads sat).
I won't ignore that sign again.
 

screenman

Legendary Member
In the absence of built in wear indicators, the lips is a second best option to use.

Stay safe, could have been a tad nasty on the front at speed.
 

dan_bo

How much does it cost to Oldham?
Location
Failsworth
It's a Mavic Open Pro, and despite looking at the rim and searching on line I still can't be sure that it has any.

Again, had I realised what I was looking at there were earlier clues. On replacing a tyre recently I noticed that the rim had a more pronounced lip on one side than the other, but consistent all the way round, and was still running fine ( I was looking at wheel true and how the brake pads sat).
I won't ignore that sign again.
I've had two open pros go on the sidewall on me in the past.

Just so's you know.
 

ColinJ

Puzzle game developer
Hmm ... I have a pair of Open Pro-rimmed wheels which I retired some time ago when I noticed that the rim walls felt slightly concave. I haven't measured the wall thicknesses but I didn't want to risk exploding a wheel when braking for a bend on one of my local 50+ mph descents!
 

Globalti

Legendary Member
I've had this happen on a mountain bike in the pre-disc brake era. The inner tube came out but didn't burst so ended up wrapped around the wheel like a demented anaconda. It's one reason why it's a good idea to pump your tyres just before a ride - if the rim is going to fail, it will probably happen as you increase the pressure.

I once ruined a rim by riding in snow with grit trapped under the brake block. The brakes got iced up and stopped working so in an effort to warm them up I squeezed them on even harder. There was a horrible graunching noise and unbeknown to me a piece of grit trapped in the icy brake block was cutting a neat groove around the rim, which split open very soon afterwards.

It's simple to tape a replacement rim alongside the old one and transfer the spokes over one by one.

The disc brake wheels on my mountain bike were second-hand when I bought them and have given me around 15 years of great service, still running as true as the day they were built. That's the reason why discs for road bikes can't come soon enough for me.
 

Globalti

Legendary Member
Just take it easy, get youself in the right frame of mind with a nice cup of tea or a cool beer, good lighting, a quiet, warm place to work and lubricate the ends of the spokes before refitting the nipples.

If it's a rear wheel you can make yourself a simple dishing gauge out of a length of wood batten with a screw through the middle and two more at the ends where the heads will contact the rim. Set the protruding lengths of the three screws so that you can gauge the rim to be in the exact centre of the axle and therefore central in the frame.
 

Dogtrousers

Kilometre nibbler
Get some dentist's calipers, less than a fiver off eBay. Have a check every so often.
This thread has moved the state of some of my rims up from vague concern to "should do something". I'll be miffed if they are bad as they are only about 3-4,000 miles old.

Am I right in thinking that the calipers you refer to are something like these?
http://www.ebay.co.uk/itm/DENTAL-OR...ab_Equipment_Medical_Equipment_Instruments_ET

They will enable me to measure rim walls to within 1/10 mm, so I guess an average of a number of readings would be required.
 
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