Back wheel jumping and sliding - cause?

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mnichols
Posts: 1463
Joined: 22 Apr 2013, 4:29pm

Back wheel jumping and sliding - cause?

Postby mnichols » 22 Jan 2017, 4:48pm

Had a fall today, quite nasty landed on my head. Back wheel just flipped out from under me on a bend. It was just like someone kicked the wheel out from under me.

This had happened a few times on the ride before, but to a lesser extent and I managed to recover the balance. The wheel just jumped or skipped sideways

I'm running Robino Pros at 100psi on Ultegra Wheels. I was probably doing about 20mph. The ride average was 18 and it was skipping on the long flats

Anyone know what might cause this?

Valbrona
Posts: 2367
Joined: 7 Feb 2011, 4:49pm

Re: Back wheel jumping and sliding - cause?

Postby Valbrona » 22 Jan 2017, 5:25pm

Petrol/oil on road. Near a petrol station or HGV depot?
I should coco.

Scunnered
Posts: 224
Joined: 11 Apr 2014, 11:23am

Re: Back wheel jumping and sliding - cause?

Postby Scunnered » 22 Jan 2017, 5:34pm

Happened to me today as well, although I didn't fall. If it's not diesel, then it's likely to be wet muck. I ride back roads where possible, but farm vehicles leave muck on the road. This afternoon I changed my tyres to ones with significant tread (was using Voyager Hypers), time will tell if this makes a difference.

fastpedaller
Posts: 2673
Joined: 10 Jul 2014, 1:12pm
Location: Norfolk

Re: Back wheel jumping and sliding - cause?

Postby fastpedaller » 22 Jan 2017, 5:50pm

Maybe Ice?

Cyril Haearn
Posts: 14553
Joined: 30 Nov 2013, 11:26am
Location: Leafy suburbia

Re: Back wheel jumping and sliding - cause?

Postby Cyril Haearn » 22 Jan 2017, 6:27pm

Maybe you were just going too fast, that could be why you slipped several times before. I would take that as a warning and go slower. Maybe you should use heavier tyres in the winter, they will slow you down a bit more.

Anything that reduces speed is welcome - or does that only apply to motors? :?
Entertainer, idealist, intellectual, PoB, 30120
Cycling-of course, but it is far better on a Gillott
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PDQ Mobile
Posts: 3850
Joined: 2 Aug 2015, 4:40pm

Re: Back wheel jumping and sliding - cause?

Postby PDQ Mobile » 22 Jan 2017, 6:52pm

Were you braking at all?
Contamination of the rim can cause "snatching".

mnichols
Posts: 1463
Joined: 22 Apr 2013, 4:29pm

Re: Back wheel jumping and sliding - cause?

Postby mnichols » 22 Jan 2017, 7:09pm

No I wasn't braking.

I'm wondering if my tyres were over inflated? I was feeling every bump which is unusual on that bike. Maybe the pressure gauge is wrong, or under-report the pressure in the cold.

A friend reminded me that my mountain bike was jumping a couple of weeks ago. Only two common factors: me and the track pump

Also I just remembered that I wasn't getting any traction on the climbs yesterday. I had to stay in the saddle. If I stood up I was will spinning

Threevok
Posts: 195
Joined: 30 Sep 2016, 3:11pm

Re: Back wheel jumping and sliding - cause?

Postby Threevok » 22 Jan 2017, 7:16pm

Sounds like the footprint of the rear tyre is minimal. I would definitely check the pressure.

Ruadh495
Posts: 413
Joined: 25 Jun 2016, 11:10am

Re: Back wheel jumping and sliding - cause?

Postby Ruadh495 » 23 Jan 2017, 1:11pm

Sounds like black ice to me.