Wet Manhole Covers

waddlie

Had one hell of a moment this morning. Hammering round a roundabout, it's dark and raining. Hit a manhole cover and holy cow I'm all over the place. Managed to stay on and completed the rest of the commute in a more languid fashion.

My question is this. I use to ride over these things all the time with my knobblies and never had any problems, but since I switched to gatorskins they're really becoming an issue. Surely knobblies aren't any more use on wet metal?

Also, given that forum members are getting knocked off on an almost daily basis, could we possibly have a well-researched sticky providing advice on claiming for damage and injuries?

cjcp

I think there is a thread on accidents and injuries somewhere.

Re the Gatorskins and man hole covers, I don't think any road tyres are particularly great over them when riding if you're leaning the bike a little. Some compounds are "stickier" than others in the rain though, and I don't think Gators are among the stickiest.

prj45

Knobblies may give you a purchase on features of a manhole cover that slicks do not, possibly giving you more perceived "grip", but slicks will give you better grip on a featurless drain cover than knobblies (given an equivilant compound).

On the road the more rubber contacting the surface the better basically, and knobblies rob you of this.

A while back they made F1 cars sport tyres that had grooves in them which was intended to mean that they couldn't corner as fast: less rubber on road surface = less grip.

prj45

Oh, and slowing down int he rain helps (but I see you learnt that)!

Headhuunter

Wet manhole covers are always a nightmare to the cyclist, especially if you're turning at the same time. They always, always cause slips. If I have the unlucky choice of either rolling over wet metal or hitting a pothole, it's the pothole every time

graeme_s-2

Maybe you were cornering faster and leaning over further on your slicks than you would have been had you been on knobblies, which left you with the impression that the knobblies were grippier in those circumstances, when in fact you were just going slowing.

Stay off the metalwork and paint when it's wet!

greg66_tri_v2.0

Graeme_S wrote:

Stay off the metalwork and paint when it's wet!

+1

You can be ok on wet metal if you're moving in a straight line going forward, dead upright. There are a couple of expansion strips on Albert Bridge, and a few times I've had the back wheel spin on those.

Any sort of angle though, and you're looking at a fall. Learnt that years ago riding round the back of a car in a queue. Low speed, but standing up. Turned the corner to join the n/side filter lane and stamped down whilst on a large piece of metalwork. On my @rse before I knew I was falling.

Treat wet metal and lines like potholes. Ride round them.

roger_merriman

the type of bike makes quite a difference as well on the old roadie if I clip metal work etc she will step out. even slowly doesn't grip, that well.

on the town bike 38mm with lightly treaded tires even being quite cavalier at worse it slowly steps out, it's a big heavy bike that doesn't do any thing fast....

the MTB has mud spike tires, but even so is a lot wider and lower pressure so there is a lot of rubber on the road so unless one was behaving in a truly hooligan way metalwork/paint is not a issue frankly neither is kerbs, parked cars......

thats not to say slicks wouldn't give better grip but other factors can have more effect.

jonginge

Greg66 wrote:

Graeme_S wrote:

Stay off the metalwork and paint when it's wet!

+1

You can be ok on wet metal if you're moving in a straight line going forward, dead upright. There are a couple of expansion strips on Albert Bridge, and a few times I've had the back wheel spin on those.

Any sort of angle though, and you're looking at a fall. Learnt that years ago riding round the back of a car in a queue. Low speed, but standing up. Turned the corner to join the n/side filter lane and stamped down whilst on a large piece of metalwork. On my @rse before I knew I was falling.

Treat wet metal and lines like potholes. Ride round them.

Yep, avoid if at all possible. On the commute I know where all the hazards are and ride to miss them. Some you can't miss due to circumstances on the road. There used to be a sunken drain cover close to the morpeth that I seemed to aim at with alarming regularity. Bunny-hopping was the way forward It becomes instinctive after a while.

snailracer

Tread and compound are not the only factors, tyre pressure and width make a huge difference when cornering over manhole covers. A wide, low pressure tyre just envelopes the bumps, maintaining grip, while a narrow, high pressure road tyre will likely skip into the air, thus losing all traction.

waddlie

prj45 wrote:

Oh, and slowing down int he rain helps (but I see you learnt that)!

The manhole incident occurred only a week after I had a major speedway moment crossing some wet tram rails at a more oblique angle than was perhaps necessary. It'll probably take a really big wipeout involving flashing blue lights and a broken bike before I really learn my lesson...

redvee

Graeme_S wrote:

Stay off the metalwork and paint when it's wet!

There are some paving slabs with pimples on them that make the bike move off line when going straight only an inch or so but enough to make you wary.

benno68

I've had a couple of scary moment's on the Kenda's that came with my Giant Defy and Michelin Krylion's that I've got now. It definitely makes things interesting though. Road bike's and metalwork in the wet don't get on, I can't speak for mountain bikes or knobblies.

Let's get this sorted out once and for all...anyone putting their name down as a crash test dummy? I'll be the camera man

jimmcdonnell

It doesn't help that the road planners put all manhole covers (sorry, 'personal access hatchways') directly in our riding line, does it? I motorcycle as well, and from a following viewpoint it must look I weave crazily around the road at times just trying to avoid metalwork.

salsajake

knobblies could give a slip-grip-slip-grip effect, meaning you stay on, a bit like abs or traction control, slicks is just an ever increasing slip. just a theory, can't back it up