... about tyre "squirm"?

EdinburghFixed · Post by **EdinburghFixed** » 18 Feb 2009, 4:55pm

This morning I almost binned on the local gyro when the back wheel seemed to 'squirm' aside beneath me. It's happened a couple of times before but previously I considered road paint (the destinations written in lanes) to be responsible.

This time there was no ready explanation - I wasn't canting over particularly aggressively, I wasn't off the saddle, the road was perhaps a bit rough but nothing I don't ride over every day (literally!)

Is it even possible for a tyre to move sideways without skidding? That's what it feels like - but if the tyre lost traction I can't see why it wouldn't slide right out and throw me.

It's only happened since I switched to the Marathon Pluses (now thankfully on the last leg there). Although they're not slick, they don't really have much tread to speak of...

It doesn't look like there is any bulge or deformity in the tyre.

Any suggestions?

AndyB · Post by **AndyB** » 18 Feb 2009, 5:00pm

I'm not sure if it's the same as you describe, but I've found the roads round here really slippery the last couple of days. I've had at least 3 minor twitches, none of which caused me to crash or fall. It tends to be like this when the weather is damp, but not wet, after a few dry days - a good rainfall clears it up.

Post by Si » 18 Feb 2009, 5:13pm

Could be the molasses in the gritting :wink:

byegad · Post by **byegad** » 18 Feb 2009, 6:07pm

Wet salty roads are always a bit dicey for grip. I suspect it will improve if it either dries out and the salt gets lown off by passing traffic or, more likely, it pours down and they don't put down any more salt!

rogerzilla · Post by **rogerzilla** » 18 Feb 2009, 6:47pm

It's been really bad here, made worse by the diesel that Farmer Palmer spills all the way down the lane I use. I thought fuel was expensive?

paulah · Post by **paulah** » 18 Feb 2009, 7:21pm

he'd better hope no-one throws a ciggie out of the car window :lol:

emergency_pants · Post by **emergency_pants** » 18 Feb 2009, 8:40pm

I don't know what it is but I find it even more obvious when I'm on the vespa... some days I find roundabouts can be quite hair-raising and I have to ease right down because I can feel the bike losing grip.

It must be something to do with dew point / air moisture, mixed with the grit and dirt on the road.

It's especially bad when it hasn't rained for a long time and then you get a bit of rain... the road is greasy with dust and diesel and that little bit of moisture on the ground turns it to something more slippy than a slippy thing on a slippy slide.

If you find the road suddenly feels greasy then I go for the diesel explanation. Diesel is horrendously slippy.

ferrit worrier · Post by **ferrit worrier** » 18 Feb 2009, 9:06pm

I've had a couple of "Twitches" just over the last few days I've put it down to dry daytime weather, rubber off vehicle tyres then being moistend by early morning dew or a bit of light rain. And, I've just changed my tyres round from front to back so I've got better ruber on the back. I'll watch what happens as spring comes round, only a few weeks now

EdinburghFixed · Post by **EdinburghFixed** » 18 Feb 2009, 10:16pm

Here here - as soon as it gets warm enough that I wouldn't mind fixing a flat, I'm going to swap the Marathons back off for the nippy (but I *won't* say "faithful") GP4000s!

gaz · Post by **gaz** » 18 Feb 2009, 10:45pm

rickangus · Post by **rickangus** » 18 Feb 2009, 10:57pm

I had a similar experience when using some tyres that were, in reality, too wide for the rims they were mounted on.

I managing to contain it by ensuring the tyres were pumped to their maximum - though that gave a harsh ride but preferable nonetheless.

Then made sure I got the tyre/rim combination correct (check Schwalbe website for details if you think this might be your problem).

meic · Post by **meic** » 19 Feb 2009, 12:03am

Roundabouts are a classic place for a bit of diesel sloshing out of overfilled tanks or from puddles in vehicles bodywork.
Also there is a nice layer of tyre rubber for it to sit on.

Did you smell diesel? Or see the tell tale rainbows?

zenzinnia · Post by **zenzinnia** » 19 Feb 2009, 8:27am

I get this, or something similar, when my tyres are a little deflatted and need a top up of air. I find they don' need to be down that much and if they go down further it goes away too.

fatboy · Post by **fatboy** » 19 Feb 2009, 8:44am

On Tuesday night I found it to be darn slippy everywhere (I nearly came off coming to our evening ride meet point, One of my friends actually did come off on the way). What this then meant was that I was unrelaxed and tense and this aggrevated the problem. After a couple of beers I was more relaxed and rode back without incident :wink:

So I think that we just need to wait for the roads to get cleaner and in the meantime take it easy!

rickangus · Post by **rickangus** » 19 Feb 2009, 9:53am

I think that if the rear tyre actually lost traction, in a similar way as a power slide in a RWD car, you would be off the bike and onto the tarmac before you even realised what was happening.

I'd be pretty sure it is a tyre pressure issue or possibly incorrect tyre sizing.