Too-smooth Tarmac?

daveydave43

A few crash threads on here; guess who also had one?
Lovely day yesterday, was cycling through Nailstone, near Coalville, and there's a downward chicane-like bit in the middle of the village. First half of the corner was fine, on the second half, exiting the corner, my wheel lost grip and skidded, causing a fall onto my left, rolling over onto my face.
Damage of 16 stitches, some lovely bandages and road rash. First ride in an ambulance aswell
But, whilst i was there both me and the paramedic had a look at the corner: it was try, there were no manholes, but the middle of the lane was quite smooth. Also, a few motorcyclists went past, i assume they were local because they used a different line to me, keeping the inside on the more abrasive Tarmac.

From your opinions, can you have road that is too smooth for grip; has anyone else has a similar event? Possibly more importantly, should i notify the council and get them to have a look at the road?

Ands

Sorry to hear about your crash Dave. I was one of the others who crashed this weekend.

So you got to ride in an ambulance....but what happened to your bike? I'm intrigued now as to what happens to people's bikes when they crash!

Hope you heal up and get back on the bike soon (how is the bike?).

Is it newly surfaced tarmac? It might be worth notifying the council - with some pics of your injuries.

WisePranker

Ands wrote:

So you got to ride in an ambulance....but what happened to your bike? I'm intrigued now as to what happens to people's bikes when they crash!

We always stick patients bikes in the back of the Ambulance with us and take them to the Hospital where they can lock them up. Failing that, we give them to the police who take them to the local nick for safe keeping

CiB

Unless it really is baby-smooth the tyre will grip on the minor imperfections on the surface. You haven't mentioned it being damp and it was a nice day yesterday, so it's more likely that you just pushed a bit too hard. Put it down to experience, but to find the limits sometimes you have to exceed them. Alternative view is the advice that my then-LBS chap in Hinckley [just down the road from Nailstone] once gave me, that your nerve should give out long before the grip does. He was probably right.

Ands - it won't be newly surfaced, not if it's dead smooth (and in Leicestershire).

The only time I've had cause to leave the scene of an accident in an ambulance, I made a big point of checking that the poilce would be looking after the bike, making it clear that it wasn't £70 worth of tat from Tesco. I collected it from the station the following day, forks & wheel as manked up as when I'd last seen it.

irturner

So what speed were you doing roughly ?
I would make a point of avoiding that road but then it hits the A447 at a dubious bend anyway. I find the bottom of one of the dips between Heather and Ravenstone smooth enough to be worrying.

daveydave43

Bike well looked after: it got taken into the ambulance with me and was kept with hospital security in the staff bike shed. They even provided a lock, so cheers to Leicester Royal for that.
The tarmac was not new at all: the middle third of the lane was smooth, the two outer thirds were slightly rougher. I weigh 63 kg and had the tyres at 95 and 100 psi f/r
Speed was in the region of 17-20mph.
Sorry to hear about your crash too Ands; hope it wasnt too bad!

Ben6899

Glad you're on the mend, mate.

Speaking as a civil engineer... it is possible the 'smooth' stretch of 'tarmac' you refer to was displaying characteristics of 'fatting up' where the bitumen bleeds through the gaps in - and over - the aggregate and creates an effectively smooth surface. If you pushed too hard at the wrong angle on a particularly fat section of carriageway, then that might explain what happened.

The first pics here are "fatted up" carriageway road surfaces. They feel super smooth to ride and drive over, but they're pretty much useless!

http://www.highwaysmaintenance.com/rtxtpics.htm

Pross

As another highway engineer I'd concur with Ben in that the only likely way a surface would be slippery enough when dry to cause a problem would be due to fatting up but this normally occurs in recently laid roads (modern SMA surfacing is renowned as being a problem when first laid to the extent that some Authorities no longer use it and others require 'slippery road' signs for months after it goes down). Road surfacing has to provide a certain level of 'polished stone value' which is basically how grippy the aggregate in the road is and which determines the skidding resistance of the road. The value differs depending on the type of road but I wouldn't expect a road to be poor enough for a bike tyre to lose grip. Far more likely you've just over cooked it a bit as there will always come a point where the forces on the wheels are greater than the friction of the surface. Alternatively it may be that there was a bit of an oil spill on the road. It is possible that the surface has become worn out to the extent that it doesn't meet the required PSV any longer but the Council should have a maintenance regime in place that includes testing the skidding resistance of the surface.

Ben6899

Pross wrote:

As another highway engineer I'd concur with Ben...

[slight thread hijack]

Hope you're having more luck than me in this difficult period, mate.

[/slight thread hijack]


As you were...

daveydave43

@ Pross and Ben
cheers for your expertise guys, from memory i think the road looked similar to the pictures, although ill have another look soon. Is it more likely that the fatting up phenomenon occurs in the centre of the road, as this experience and pics indicate?

Ben6899

daveydave43 wrote:

@ Pross and Ben
cheers for your expertise guys, from memory i think the road looked similar to the pictures, although ill have another look soon. Is it more likely that the fatting up phenomenon occurs in the centre of the road, as this experience and pics indicate?

No worries. In my experience, I've witnessed it in the wheel tracks and in the middle of the lane. Like Pross says though, it would still need a combination of factors to cause you to take a spill - a fatted up surface of course still has some friction property.

Radioactiveman

Really enjoyed reading about different resurfacing techniques.


ARGH shoot me now I am past it

andy_wrx

I'm just thinking what an excellent link it is, how I'm going to enjoy quoting bits of it at the local authority highway engineers, when I report cr*p roadsurfaces round here :twisted:

Must admit, I'd never really thought of (what I now know is called) fatted-up road surfaces as having little grip
- in Summer the tar is gloopy stick mess that gets all over your tyres, frame, shoes, but yes, thinking about it it's the edges of the stones sticking though it which give the grip, not the tar.

What's the technical term for it when the local authority have top-dressed a road, traffic has then swept off the chippings and left the tar exposed, i.e. a pair of smooth-tarmac black wheeltracks with area of loose chippings in between ?
I must admit I have tended to ride in the wheeltracks, thinking that was grippier than the loose chiipings area between them...

Berk Bonebonce

Smooth road surface = more contact with tyre = safer road.

daveydave43

^^^
right, so, what about ice then?

dmch2

daveydave43 wrote:

^^^
right, so, what about ice then?

The ice melts under the pressure of the tyre so then you have no contact between the tyre and road surface. And you fall off and decided to buy a turbo trainer for the winter...

Stone Glider

Is that what was the problem in the TdF this year? The stage where Chinny had the finish neutralised. IIRC There was some comment that deisel had been spilt onto a downhill section but another report said it was a freshly laid stretch of tarmac.

Any expert view on this?

Pross

Berk Bonebonce wrote:

Smooth road surface = more contact with tyre = safer road.

This can theoretically be the case in the dry (providing the bitumen hasn't leeched through and covered the aggregate) but in the wet you rely on the texture of the aggregate to provide contact over the water. Besides the lack of surface contact due to the gaps between the aggregate would be negligible in real terms.

Not sure what happened in the Tour this year but there is a risk that a newly laid surface could have fatted up. I think it was wet on that stage so if the bitumen had come to the surface then there is a good chance it may have contributed.

Thick Tester

Sounds to me like you need to learn how to corner properly and stop attempting to transfer the responsibility away from yourself.

I've had a good look on Google maps and theres nothing a decent rider should not be able to handle in Nailstone

markmod

pm'ed you Dave.

daveydave43

@ Tester
I do accept that i may have overreached it here and i do accept responsibility for the fact that i crashed. The post was more about my surprise at crashing on this corner; you are right, its not very technical at all. The front tyre felt, to me, as if it slipped/skidded, whatever you want to call it.
If there was a problem with the road, i thought it would be better to find out what it was and point it out?
And on a final point, I consider myself able to corner.

markmod

Tester I think your point about any corner in Nailstone not being technical backs up Daves post, in that it shouldn't be that hard to get around it, and his surprise was actually to come off on a corner that shouldn't be that testing and as investigating the reason why this should happen.

Don't be too hard on a fellow cyclist mate, we all come off sometime in our cycling life,, even the best pro cyclists, and it's nearly always a surprise when it happens, otherwise we would do something to stop ourselves coming off right?

Thick Tester

It’s the mentality of some folk always seeking to blame others without accepting responsibility for their own actions i cannot stand. Where a simple ‘it was my fault’ would suffice we seem to have this constant drip feed of transference, and then seeking validation of their theory via an internet forum.
I would imagine that your tyres were at the wrong pressure and or in a shoddy state of repair – couple that with your admission of overcooking it and you have yourself a simple ‘ I crashed’
Only by accepting your limitations and faults will you learn from them and improve – unless of course you are a triaphrodite or a blood relative of one!