Corner speed question..........

Gav888
Gav888 Posts: 946
edited December 2008 in Workshop
Hi,

Im new to road biking so I have little knowledge of tires, but im wondering what sort of tires are used in these video's to give the level of grip and speed in the corners, as those speeds look very high in places - for a road bike.

http://www.youtube.com/watch?v=xRxia2XSpt8
http://uk.youtube.com/watch?v=HJoqtnizklA&NR=1

I would think things like compound / tread / size / PSI would have an effect on the corner speeds and grip, but to what extent on a road bike, is there alot of difference between the different makes of tires? Im used to motorcycling and the right tires make a big difference.

Also, how do you know when your tires are about to stop gripping, is there a feeling you get, or is there no warning?
Cycling never gets any easier, you just go faster - Greg LeMond
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Comments

  • softlad
    softlad Posts: 3,513
    sliding down the road on your arse is a sure sign that your tyres have stopped gripping.. ;)

    Seriously, its difficult to know where to begin. All I can resaonably suggest is that you have a look around the sites of a few manufacturers like Vittoria, Michelin, Schwalbe or Continental and read up on a few of the tyre types, compounds, etc. A lot of it is down to presonal preference, but if you have a specific type of riding in mind, I'm sure people will be able to suggest a few good tyres for starters...
  • Gav888
    Gav888 Posts: 946
    Thanks for the reply softlad.

    At present I have no specific type of riding, im just trying to build my fitness and speed levels at present as im rather unfit so I will stick with whats on the bike. But come Spring / Summer when its warmer I would like to take on some nice smooth twisty roads with some good downhill sections, so grip, speed and being able to maintain a good corner speed become important to me.

    Some recommendations would be great. Unsure about the price, does £50 or so sound reasonable for good tires?
    Cycling never gets any easier, you just go faster - Greg LeMond
  • The contact area for road tyres is so small that the maximum braking force is tiny - the brakes on a road bike are for tempering and controlling speed not for any serious stopping power. Ditto with the tread pattern - with such a small area the water displacement requirements are minimal and won't be much help for grip.

    Indeed, you're main concern should be about getting maximum speed - the tyre material is capable of going faster than is humanly feasible - so tyres with a no tread and a high pressure and quality make will suit you well.

    If it's wet or oily etc. then obviously you can't do anything like those videos, but your main aim should be getting up to those speeds, not what will happen when you get there :wink:
  • Higher TPI counts (more flexible carcass) and softer compounds help. Continental GP4000S with the black chilli compound are very sticky in the dry.

    At this time of year though, safety first! I corner like a granny on a Pashley, its far too easy to break something and be off the bike for weeks.

    @ 40 secs in the first clip, when they couldn't use the full apex due to the oncoming red car - I would have bricked it!!
  • djaeggi
    djaeggi Posts: 107
    Yes, there's a fair bit of difference between tyres, much the same as with cars/motorbikes. I'm by no means an expert on high speed cornering, but certainly compound and casing design has a large impact. Tread is virtually a non issue on asphalt because there's no risk of aquaplaning given the tyre size/loads. Pressure and size makes a difference because you're changing the contact patch size, and also the deformation under cornering. Quite what works pressure wise is, as with a motorbike, dependent on the particular tyre and your weight. Generally: run lower pressures when grip is low and thus cornering speeds are low as you're not going to deform the tyre in the bend as much and will appreciate the larger contact patch; in the dry, you can happily run higher pressures.

    Grip limits. Again, like other tyres, there are two approaches to tyre feedback. Some tyres will hit a nice grip plateau which you can feel as a drift; others will warn you with stuttering. After the limit, the magnitude of the loss of grip will vary too. As on a motorbike (I guess!) and car, losing the front end is preferable to losing the rear - getting your weight rearwards on a descent can help you out, and also help your braking.

    Basically, any of the top tyres from the major manufacturers (Michelin, Conti, Vredestein, Schwalbe, Vittoria) will do the job, albeit with different compromises between wet/dry grip, cost, wear, rolling resistance, feel. It appears (not having ridden either yet) that the latest Conti GP4000 and Michelin Pro Race 3 seem to have raised the bar somewhat.
  • Hi there.

    Here's a link I keep reposting!

    http://www.conti-tyres.co.uk/conticycle ... ghters.pdf

    Cheers, Andy

    ps Something that struck me from one of the above videos, is something I see bikers do all the time round here. If you're taking a blind bend where you're leaning into oncoming traffic, it makes sense to keep you head on the correct side of the road, not just your tyres!
  • aracer
    aracer Posts: 1,649
    All other things being equal, wider tyres should give more grip than narrow ones (as with motorbikes), since the size of the contact patch makes a difference. Though you tend not to get sticky race compound rubber in wider than 25mm.
  • Gav888
    Gav888 Posts: 946
    Hi there.

    Here's a link I keep reposting!

    http://www.conti-tyres.co.uk/conticycle ... ghters.pdf

    Cheers, Andy

    ps Something that struck me from one of the above videos, is something I see bikers do all the time round here. If you're taking a blind bend where you're leaning into oncoming traffic, it makes sense to keep you head on the correct side of the road, not just your tyres!

    Cheers for the link, I hadnt seen that before :wink:

    Regarding keeping your head in, im used to that being a motorcyclist, many a time ive been leaning over the middle of the other lane, not nice when a car is coming!!!

    Also, another question ive just thought of, on a Motorcycle, and a car for that matter, the front brakes are much bigger and do the majority of the stopping. On a cycle the front and rear are the same, do you apply 50/50 force, or more 70 front / 30 rear?
    Cycling never gets any easier, you just go faster - Greg LeMond
  • Gav888 wrote:
    Cheers for the link, I hadnt seen that before :wink:

    Regarding keeping your head in, im used to that being a motorcyclist, many a time ive been leaning over the middle of the other lane, not nice when a car is coming!!!

    Also, another question ive just thought of, on a Motorcycle, and a car for that matter, the front brakes are much bigger and do the majority of the stopping. On a cycle the front and rear are the same, do you apply 50/50 force, or more 70 front / 30 rear?

    Hi there.

    On the road - 90% front brake. I really only use the back one in anger if I'm deep into a corner and in trouble...

    Cheers, Andy
  • aracer
    aracer Posts: 1,649
    More front than rear - hence Campag using a more powerful front brake. If you're really braking right on the limit of how fast you can slow down, then no rear brake at all as it will have no weight on it. That's assuming normal grippy road surface - if there's any chance of skidding the front tyre under normal braking, then I'd increase the rear braking as it's much easier to control if you lose that.
  • Gav888
    Gav888 Posts: 946
    Cheers, so basically my motorbike skills regarding cornering lines, weight transfer and braking will still apply :) But I dont think I will be getting my knee down in the corners though!!!
    Cycling never gets any easier, you just go faster - Greg LeMond
  • Gav888 wrote:
    Cheers, so basically my motorbike skills regarding cornering lines, weight transfer and braking will still apply :) But I dont think I will be getting my knee down in the corners though!!!

    Hi there.

    Plenty of foot-down cornering racing cross in the ice yesterday!

    I'm sure motorbike skills translate well - most importantly the concept of commitment to a corner.

    The main difference I guess is that on a bicycle you don't need to square off the corner so that you can get the power down - you take more of a continuous arc instead.

    Cheers, Andy
  • wilwil
    wilwil Posts: 374
    [

    On the road - 90% front brake. I really only use the back one in anger if I'm deep into a corner and in trouble...

    Cheers, Andy


    Sh*t, I'm doing something wrong then my rear pads are more worn than the front.
  • John.T
    John.T Posts: 3,698
    wilwil. The back gets more cr*p on it so wears faster. Rims too. I am lucky to get more than 2 winters from a rim and I use the front brake much more.
  • You get loads more feedback from a motorbike tyre than a cycle tyre ... I dunno who but with the mototbike you can feel when your on the edge but on the cycle it's either gripping or your falling; I have not noticed much warning that said since my last tumble I probably have been some way off the limit ... :?
  • softlad
    softlad Posts: 3,513
    Gav888 wrote:
    Cheers, so basically my motorbike skills regarding cornering lines, weight transfer and braking will still apply :) But I dont think I will be getting my knee down in the corners though!!!

    the only thing you don't have on a cycle is throttle control, which is a big part of cornering on a m/c. Pedalling on a high speed corner when you are cranked over is not usally a good idea, because of how if affects weight transfer and balance - plus there is a risk of grounding the inside pedal..
  • DaSy
    DaSy Posts: 599
    The knee out on corners is not a good look on a bicycle, it really isn't necessary unless you are descending a mountain, and need to use it as a bit of an air brake going into the bends.
    Complicating matters since 1965
  • ColinJ
    ColinJ Posts: 2,218
    djaeggi wrote:
    After the limit, the magnitude of the loss of grip will vary too. As on a motorbike (I guess!) and car, losing the front end is preferable to losing the rear...
    Eh - I don't think so!

    When your front wheel slides out from under you, you go down hard and fast, as I know from a couple of painful experiences. It's almost impossible to recover from.

    When your back wheel starts to slide, if you react quickly you can recover from it. I've done it myself lots of times and I've seen other riders do it.

    When you see a touch of wheels in a race, it's always the rider at the back who goes down because (s)he lost the front wheel. The rider in front often barely notices the collision.
  • wilwil
    wilwil Posts: 374
    John.T wrote:
    wilwil. The back gets more cr*p on it so wears faster. Rims too. I am lucky to get more than 2 winters from a rim and I use the front brake much more.

    I did 100 miles this weekend and Sunday was quite wet. When I cleaned the bike on Sunday afternoon the black stuff that kept coming off the back rim was unbelievable compared to the front rim. I have Campag brakes so the back brake shouldn't have the power of the front brake.

    Is this brake pad debris or just general cr*p?
  • Gav888
    Gav888 Posts: 946
    ColinJ wrote:
    djaeggi wrote:
    After the limit, the magnitude of the loss of grip will vary too. As on a motorbike (I guess!) and car, losing the front end is preferable to losing the rear...
    Eh - I don't think so!

    When your front wheel slides out from under you, you go down hard and fast, as I know from a couple of painful experiences. It's almost impossible to recover from.

    When your back wheel starts to slide, if you react quickly you can recover from it. I've done it myself lots of times and I've seen other riders do it.

    When you see a touch of wheels in a race, it's always the rider at the back who goes down because (s)he lost the front wheel. The rider in front often barely notices the collision.

    Have to agree there, on a M/C you dont stand a chance of saving the front when it goes, only a world class racer like Rossi can - sometimes, and that is only if you have your knee on the ground and you hold the bike up a bit, on a road bike, your knee isnt down, so your history, and as you say, with the rear you have a small chance of saving it if your quick enough.
    Cycling never gets any easier, you just go faster - Greg LeMond
  • John.T
    John.T Posts: 3,698
    The black stuff is a mixture of road grime and alloy dust all mixed up into a good grinding paste. It destroys rims. As you do not apply the rear brake as hard the pads do not clean the rims as well. This makes things worse.
    I do not go along with the Campag theory re brake differentials as you need different brake pressure for different circumstances so you still control it at the lever. I see no point in having a less efficent brake on my bike.
    ColinJ is right about not loosing the front wheel. You very seldom get it back whereas you can recover a rear wheel by letting the rear brake off or steering in to the skid and picking the bike up a bit.
    As regards the OP. Any good quality tyre will be fine. The main requirments are a combination of experience and leaving your brain at the top. It is good fun when you get it right though.
  • djaeggi
    djaeggi Posts: 107
    ColinJ wrote:
    djaeggi wrote:
    After the limit, the magnitude of the loss of grip will vary too. As on a motorbike (I guess!) and car, losing the front end is preferable to losing the rear...
    Eh - I don't think so!

    When your front wheel slides out from under you, you go down hard and fast, as I know from a couple of painful experiences. It's almost impossible to recover from.

    When your back wheel starts to slide, if you react quickly you can recover from it. I've done it myself lots of times and I've seen other riders do it.

    Fair enough! The (very) few times I've fully lost traction on either front or rear round a bend, I've fully lost the bike :-) But i know a guy who rides motorcycles quite seriously and I know that rear-wheel slides on a motorbike can be quite bad news.
  • djaeggi
    djaeggi Posts: 107
    Ah, (some internet research later) the issue with motorcycles (which doesn't apply to bikes) is the side of the bike on which you land, and thus whether the bike has a chance of hitting you or not, rather than the controllability. I.e. losing the front on a motorbike results in you hitting the deck on the inside with the machine in front of you; losing the rear can result in you going over the top and the bike landing on you.

    I take back my comments - I don't like losing grip at all on a bike so I try to avoid it at all costs!
  • John.T
    John.T Posts: 3,698
    A front skid is safer in a car (under steer) as so long as you do not lock the wheels and have room to run wide you will recover. You do not fall off a car. If you watch motor bike racing you will often see the rear wheels well out of line under braking and some rather hairy moments under power but if they loose the front they do not often stay on. The dynamics are quite different.
    Edit. Wether you 'high side' or not is more a result of what the motor bike does immediatly after you loose either end and is caused by a tyre regaining grip but not going in the direction you want. Very basic answer.
  • djaeggi
    djaeggi Posts: 107
    Interesting, thanks!
  • balthazar
    balthazar Posts: 1,565
    Gav888 wrote:

    Also, how do you know when your tires are about to stop gripping, is there a feeling you get, or is there no warning?

    There is no warning. On good dry roads, if you corner so fast that you exceed the grip of your tyres, you go down. I don't believe any cyclist ever "drifted" a road bike.

    Few people get near this limit, luckily, because everybody underestimates the grip available. Most riders will bail into a hedge on the outside of a corner they probably could have ridden round, if only they believed it possible. Professional riders can be seen doing this every year in the TdF.

    The photograph of JB on the right here, shows the lean angles that are possible.

    http://www.sheldonbrown.com/brandt/

    His article

    http://www.sheldonbrown.com/brandt/descending.html

    may interest you.
  • balthazar wrote:
    There is no warning. On good dry roads, if you corner so fast that you exceed the grip of your tyres, you go down. I don't believe any cyclist ever "drifted" a road bike.

    Hi there.

    I've just finished reading Yellow Fever, which is a bit dated now, but basically chronicles the 1998 Tour de France. Amongst all the tears, drug busts and toys being thrown out of the pram there were some good snippets from a young Magnus Backstedt on his first tour.

    Magnus is now reknowned as one of the best descenders in the business, although his efforts rarely get on TV as he's usually mentalling down the hill with the other sprinters in pursuit who've been dropped by the peleton on the way up. When asked recently about the legendary descending skills of Paulo Savodelli he nonchalantly shrugged and said that he'd dropped him on a descent before.

    That's the long winded introduction, but basically when asked in '98 about descending the cols he casually said that the bike would slide around in the corners, and this was 'normal' you just had to get used to it.

    Cheers, Andy
  • balthazar
    balthazar Posts: 1,565

    Magnus is now reknowned as one of the best descenders in the business, although his efforts rarely get on TV as he's usually mentalling down the hill with the other sprinters in pursuit who've been dropped by the peloton on the way up. When asked recently about the legendary descending skills of Paulo Savodelli he nonchalantly shrugged and said that he'd dropped him on a descent before.

    That's the long winded introduction, but basically when asked in '98 about descending the cols he casually said that the bike would slide around in the corners, and this was 'normal' you just had to get used to it.

    Cheers, Andy

    Pros tell porkies too. Magnus was certainly a fast and flamboyant downhiller, but I maintain that he - or anybody else - never controlled a slide on a good dry road.

    Best, b
  • softlad
    softlad Posts: 3,513
    to be fair - his tubs would probably have rolled before the bike slid....
  • balthazar wrote:

    Hi there.

    If you can get past the almost overbearing condescending tone, that is actually a very good article!

    Cheers, Andy