The impact of dry mud on 700 25c tyres

[doffcocker]

Hi all,

Yesterday I was out on the road, and the bike randomly lost grip on the surface when I was turning at only a very minute angle and I fell. It seemed really odd as the only time I've experienced this before was in icy conditions and it wasn't much of a shock at the time. But this seemed to happen out of nothing until I inspected the tyres closely to realise they were caked in dry mud from the previous day. I don't normally bother to look or even notice this sort of thing before jumping on the bike and out onto the road because I have never until now seen it as a safety hazard. I just want to have it confirmed that this will probably have been the sole cause of the slide so that I can just keep a closer eye on it in future, because although I'm not badly hurt by it it has certainly scared me a little, especially considering how bad it could have been had a been moving at speed.

Cheers.

[NATURAL ANKLING]

Hi,
On my local training ride, I have a track to climb.
Damp or even very wet its not to bad, but dry and dusty mud I get wheel spin.
I always look out for dry and dusty on the road, gravel dry mud sand even on a hard surface.
Very possible that if the tyre was covered even the tread (if any?) was full of dry mud, that it could be less than grippy.

[DevonDamo]

...I just want to have it confirmed that this will probably have been the sole cause of the slide so that I can just keep a closer eye on it in future

You aren't going to get a categorical answer to that one unless you had a video of the incident and close-up photos of the road surface and your tyres - preferably prior to the slip. Mud on your tyres would have an effect on friction, but I'd be extremely surprised if this reduction in friction would be sufficient, on its own, for you to lose your front end when cornering at such a low angle - i.e. with minimal centripetal force to balance out. I'd have thought any gross contamination would fall off as soon as you got rolling and squashing the tyre onto the tarmac. Other friction causes would be either 'loose' road contamination, e.g. fine gravel, 'slippery' road contamination, e.g. a diesel spill or tyre contamination, e.g. over-zealous use of grease whilst servicing. Non-friction causes might include not having enough weight on the front wheel (either because of the bike's geometry, or where you or your luggage are located on the bike) or braking whilst cornering. Mechanical contributors might include badly knackered wheel bearings or headset.

I lost my front wheel in spectacular fashion when I was a youngster and never recovered my confidence in cornering on a bike and later on motorbikes. It's only recently, since I've taken up mountain biking, that I've been forced to confront my demons. In my case, I've learned that a big problem for me is that, whenever I'm in fear of losing my front wheel, my unthinking reflex is to move away from the 'danger,' i.e. push myself back away from the front wheel. This becomes a self-fulfilling prophecy as far as losing the front goes. Forcing myself to instead get my weight forward whilst cornering hard has been a scary process, but the dividends have been considerable and immediate. This weight-distribution effect is greatly amplified whilst mountain biking as you're often standing, with your seat lowered, able to move your bodyweight a long distance forward and back. I'd be surprised if it made much difference whilst cornering on a road bike (i.e. sat down) unless you were cornering at a speed already close to the limit of your front tyre's grip - which doesn't sound like the case in your fall.

[foxyrider]

dry mud - unless its ground to a thick fine powder on the road surface, has never caused me any issue, it comes off the tyre in just a few metres leaving at least a clean running strip, a few turns and stuff on the shoulders will be gone too. Wet mud can be picked up by tyres, i've had my mudguards full this winter from this, but a cleaner surface soon scrubs anything off.

I think your issue was more likely caused by something on the road surface, almost any corner and even some bits of straight will often have a layer of debris which can be like riding on ball bearings, i always keep a look out for this particularly when its dry, if its wet its usually easier to ride across.

[531colin]

...I just want to have it confirmed that this will probably have been the sole cause of the slide so that I can just keep a closer eye on it in future

You aren't going to get a categorical answer to that one unless you had a video of the incident and close-up photos of the road surface and your tyres - preferably prior to the slip. Mud on your tyres would have an effect on friction, but I'd be extremely surprised if this reduction in friction would be sufficient, on its own, for you to lose your front end when cornering at such a low angle - i.e. with minimal centripetal force to balance out. I'd have thought any gross contamination would fall off as soon as you got rolling and squashing the tyre onto the tarmac. Other friction causes would be either 'loose' road contamination, e.g. fine gravel, 'slippery' road contamination, e.g. a diesel spill or tyre contamination, e.g. over-zealous use of grease whilst servicing. Non-friction causes might include not having enough weight on the front wheel (either because of the bike's geometry, or where you or your luggage are located on the bike) or braking whilst cornering. Mechanical contributors might include badly knackered wheel bearings or headset.

I lost my front wheel in spectacular fashion when I was a youngster and never recovered my confidence in cornering on a bike and later on motorbikes. It's only recently, since I've taken up mountain biking, that I've been forced to confront my demons. In my case, I've learned that a big problem for me is that, whenever I'm in fear of losing my front wheel, my unthinking reflex is to move away from the 'danger,' i.e. push myself back away from the front wheel. This becomes a self-fulfilling prophecy as far as losing the front goes. Forcing myself to instead get my weight forward whilst cornering hard has been a scary process, but the dividends have been considerable and immediate. This weight-distribution effect is greatly amplified whilst mountain biking as you're often standing, with your seat lowered, able to move your bodyweight a long distance forward and back. I'd be surprised if it made much difference whilst cornering on a road bike (i.e. sat down) unless you were cornering at a speed already close to the limit of your front tyre's grip - which doesn't sound like the case in your fall.

He doesn't say it was the front end that washed out?

[531colin]

Hi all,

Yesterday I was out on the road, and the bike randomly lost grip on the surface when I was turning at only a very minute angle and I fell. It seemed really odd as the only time I've experienced this before was in icy conditions and it wasn't much of a shock at the time. But this seemed to happen out of nothing until I inspected the tyres closely to realise they were caked in dry mud from the previous day. I don't normally bother to look or even notice this sort of thing before jumping on the bike and out onto the road because I have never until now seen it as a safety hazard. I just want to have it confirmed that this will probably have been the sole cause of the slide so that I can just keep a closer eye on it in future, because although I'm not badly hurt by it it has certainly scared me a little, especially considering how bad it could have been had a been moving at speed.

Cheers.

I often have tyres caked in dry mud and bovine by-product, and this has never happened to me.
I suspect something else was at work....for example, a tiny bit of gravel on top of smooth tarmac can be like trying to rid on a load of ball-bearings.....much more tricky than the average gravel track.