Road grip cornering at speed

[derrick]

Only problem is, once your committed to a high speed corner its more dangerous to brake than it is to steam ahead!

Just sit up, that will knock a bit of speed of.

 

[Wobblers]

Oh dear I was hoping we could have a nice discussion without the physics.......

You have missed out the coefficient of friction between rubber and asphalt which will effect your statement. Eg. a bike running on steel rims will lose grip at much lower centrifugal forces than one with a rubber tyre. Rubber tyres and asphalt typically has a coefficient of friction of about 1.5 (up to 1.7) so you can actually lean over quite a bit more than 45 degrees....if you have the cohones to do it! Clearly any imperfections in the road surface reduce this coefficient substantially.

I thought it best to stick (ha! Stick! Geddit? ) to the simplest explanation. Yes, you may get more cohesion than I stated - but that depends on the rubber compound, and state of the road surface. I wouldn't go about relying on it! Typical values for dry road surfaces in good condition are 0.8 - 1.0. These will be less in the wet - and can be far less where the surface is contaminated. Given that I've ended up in A&E twice as a direct result of diesel I really wouldn't advise throwing your bike around unnecessarily (unless you like pain!).

 

[Bodhbh]

My experience in using Kojaks on three wheels was that they are made from a very hard rubber! I found them pretty poor for grip on chip and seal even in bone dry conditions and frankly awful in damp or wet conditions. Replacing them with Marathon Racers gave me much more grip in all conditions.

Hrmm interesting. I've not really used slicks enough to have an appriciation of the differences in grip. I always though Kojaks where a fast tyre to stick on MTBs etc for road use, however, they are even listed as touring tyres on the Schwalbe website. The bike they're on is a Roadrat for general bombing around - not commuting, touring or distance riding - just a bit of fun, I'm finding I'm doing a fair bit of gravel and trail riding as well, so they are sounding like they're not the best tyre for either.

 

[thegravestoneman]

Tubs?

 

[green1]

No and again no!

Tyre grip is limited by physics. A tyre will start to slip when you apply a force on it which is greater than the weight it is bearing. Put simply, the force needed to keep you turning in a circle will equal your weight when you're inclined at an angle of 45 degrees - assuming perfect tarmac. Above that point, you're going to start sliding whatever, and tyre pressure won't make a jot of difference. Most times you'll get less, substantially so if it's wet.

I mentioned tyre pressure with regard to the pressure keeping the tyre from massively deforming causing a spill. I'm not talking about the difference between 90 and 110 psi, I'm talking about having it at 40~50 psi when it should be 100+.

The question was about a dry gravel free road hence why I didn't go in to a wet road.

 

[HLaB]

Road bike tyres in the right hands are amazingly grippy, although I myself wouldn't go to the extreme, it just takes one peice of gravel, grease on the surface, etc and Although on a few occaisions I have had to get nearer to that extrene due to a muppet driver overtaking on a bend/rbt

 

[GrasB]

How NOT to turn a corner quickly. Best to lean your body more than the bike not the bike more than the body. Note your lean angle should be taken from the middle of the bike's BB through your belly button. Shunting your a**e out one side & leaning your shoulder into the corner moves your body angle upwards not inwards!

 

[marzjennings]

How NOT to turn a corner quickly. Best to lean your body more than the bike not the bike more than the body. Note your lean angle should be taken from the middle of the bike's BB through your belly button. Shunting your a**e out one side & leaning your shoulder into the corner moves your body angle upwards not inwards!

Best not to lean more than bike. Leaning your body more than the bike is important on a motorbike where the rider's weight is used to counteract the weight of the bike, it's just redundant on a bicycle. Either lean with the bike or lean the bike more into the corner.

 

[byegad]

Hrmm interesting. I've not really used slicks enough to have an appriciation of the differences in grip. I always though Kojaks where a fast tyre to stick on MTBs etc for road use, however, they are even listed as touring tyres on the Schwalbe website. The bike they're on is a Roadrat for general bombing around - not commuting, touring or distance riding - just a bit of fun, I'm finding I'm doing a fair bit of gravel and trail riding as well, so they are sounding like they're not the best tyre for either.

I got on OK*, on three wheels, with the Kojaks until, after about 900 miles of use, I went out in freezing weather and the damn things developed inexplicable punctures, 3 in two miles! At each puncture site there was a huge slit, over 1" long on the carcass and nothing actually stuck in the tyre. On the short push home, after giving up on repairing the damn thingss close to home I resolved to replace them with BAs, which I already used on the QNT. I was pleasantly surprised that at 70 psi on the back tyres and 55 on the front I noticed no loss in speed and an significant increase in comfort. Two of the BAs are still on the Kettwiesel after 4000 more miles, I replaced the (single wheel) drive tyre at about 3000 miles old as it was getting a bit bald!

* Well, with the Kojaks, in the wet, I noticed a reasonable amount of wheel spin on very smooth tarmac up hills and the braking was poor for a recumbent trike. On the Big Apples the wheel doesn't spin and the braking, while not up to a tadpole trike's, is much more certain. I don't think I'd use Kojaks on two wheels in the wet.

 

[GrasB]

Best not to lean more than bike. Leaning your body more than the bike is important on a motorbike where the rider's weight is used to counteract the weight of the bike, it's just redundant on a bicycle. Either lean with the bike or lean the bike more into the corner.

You want to get the bike down to about 40-45 degrees of lean. Beyond that you're losing cornering grip from the tyre. If you watch bike riders trying to out corner motorbike riders the ones who win are all leaning more than the bike. The ones who can't keep up or end up doing exactly what that guy does are all leaning less than the bike.

 

[Bodhbh]

I got on OK*, on three wheels, with the Kojaks until, after about 900 miles of use, I went out in freezing weather and the damn things developed inexplicable punctures, 3 in two miles! At each puncture site there was a huge slit, over 1" long on the carcass and nothing actually stuck in the tyre....

Ack! I'm probably going to switch over to some mixed surface tyres anyhow, either some other stripe of Marathons or maybe something less chunky like the Sammy Slicks. The bike is something of a frankenstein affair, and I wasn't really sure how it was gonna be used - long ride yesterday involved plenty of trail riding, so...