|Riding bike at cornering limit?||G-man|
Jan 30, 2002 7:49 AM
|I have driven my cars at and beyond their cornering limits. When driven at ever increasing speeds around a circle(skid-pad test), some cars started slipping in the front (understeer), others in the rear (oversteer). I've done this in large, empty parking lots so even if the car went sliding out of control there was no fear of crashing.
I have tried this on my bike, but I always chicken-out and never have really approached feeling the tires slide.
Has any of you done this? What was the result? Could you feel the tires slide? How could you tell they were sliding?Did you fall? Etc, Etc.
|Chickening out is the smart move||cory|
Jan 30, 2002 8:21 AM
|I've tested cars for several magazines, been editor of a couple and still do freelance automotive journalism...in the case of a two-wheeled vehicle, chickening out is the smart thing to do. There's no penalty for spinning a car, but the equivalent in a bicycle or motorcycle is almost always a crash. A lot of motorcycle riders can get the tail out under power (like power oversteer in a rear-wheel drive car), but it's a circus trick--it doesn't contribute much to cornering speed on pavement.
I have to admit, though, I've wondered the same thing about bikes: What would happen if I just honked into this turn way too fast and leaned farther and farther over until...? I'd crash, is what.
Jan 30, 2002 8:28 AM
|I've crashed doing this quite a few times. If you practice, you can get pretty good at doing a two-wheel slide, and then throwing you weight so that you don't fall. If you want to learn the technique, do it on some wet grass- it doesn't hurt as much.
I'd say that in a corner, most bikes I've done this with slide out in the rear. I'm guessing that's because there's not as much weight (i.e. force) on the front?
|Recover a Two Wheel skid?||Ping_Pong|
Jan 30, 2002 9:26 AM
|I have cornered too hard a few times, always with the back wheel losing grip first. Only once have I managed to recover from the slip, the first time, leading to over confidence - and the next two falls.
Recovering from a two wheel skid during hard cornering is however impossible unless a rut in the road 'remounts' you on the bike. As soon as the wheels unexpectedly lose traction you find yourself pushing the bike away from you - a really sickening feeling.
|I've recovered from a few rear skids, but never a front wheel...||Tig|
Jan 30, 2002 10:00 AM
|skid. I've only post the front wheel traction 2 times, and once the wheel turns under, you're history. They were from loose gravel near the turn apex.
Same goes with motorcycles. I've dropped them lowside when losing the front wheel, but have been able to spin the rear a little to recover from rear slides that got too wild. Avoiding a highside flip (and the taste of the resulting adrenaline) on a motorcycle is something you'll never forget!
Jan 30, 2002 10:27 AM
|You do need some change in the friction of the road- so if you're sliding on sand, and slide into clean pavement, you can recover. But if there is nothing to push your weight against, a two-wheel slide cannot be saved.|
Jan 30, 2002 5:29 PM
|You can ballance through a two wheel slide and save the bike - motorcycle racers and experienced MTB riders do it everyday, but everything gets much more critical on a road bike and the skinny tires don't help. Experienced road racers will take the bike to it's cornering limits and the tires begin to slide. |
As both wheels slide the bike will eventually lose velocity and you will transition from the regeim of being under the coefficient of sliding friction back to static friction, which is greater. This is when the bike "hooks up" and people usually get tossed over the high side as a result, but it's a function of ballance and skill. The difficulty is that there can be such a great difference between sliding and static friction. Life is much easier when the two aren't so far apart - as in the case of an MTB on dirt - or you have a skid plate on your knee like a motorcycle. This is why sand is so bad.
|No, you're right,||TJeanloz|
Jan 30, 2002 5:34 PM
|I had forgotten about the static vs. sliding friction bit. It doesn't take a change in surface to save the slide, but it does require a change in friction (which can often be accomplished with a change in surface).|
|well said, grzy! nm||gtx|
Jan 30, 2002 5:48 PM
Jan 30, 2002 4:46 PM
|I've seen Pros tripoding to gain stability when they loose it. Experience & a lot of luck goes is essential. I can imagine that it's not real predictable, as the circumstances are so variable.|
|re: Riding bike at cornering limit?||LC|
Jan 30, 2002 10:03 AM
|I do it on a Mt. Bike all the time for the rear wheel. It is a pretty neat trick to get around a sharp corner. If the front tire looses traction it usually means I am going to eat some mud, but that tastes better than concrete any day.|
|He went whoooo-hooo!||tempeteKerouak|
Jan 30, 2002 11:18 AM
|I have seen my brother skid in a turn on dry pavement; both wheels and he stayed on. (Going down Jay Peak, nasty turn, I went straight, he made it. I think he got lucky unloading and shifting his weight at the right moment; ie as he needed to straighten up. Some magical reflex!)
But I've seen Pro racers slide away in turns under very wet conditions. (In the Tour de France and at the Montreal World cup). I'm talking about going down a twisty downhill here, not a criterium leaned turn, you remain upright on the bike) They did not seemed phazed at all... I even heard a guy go "Whoooo-hooo"!
But when you loose it... Specially a front wash-out... Bye bye!
Jan 30, 2002 11:36 AM
|Interesting question. Most of the posts seem to say the rear wheel skids first. This seems consistent with the automobile experience where a car with a rear weight bias (think old VW bug or, for the more stylish, Porsche 911) will oversteer.|
|Sure beats the hell out of the wheels!||guido|
Jan 30, 2002 12:04 PM
|It's one thing to slip on a wet leaf, slide onto pavement and recover, but another to go into a full body power slide on both wheels. The sideways force on the wheels is fearsome. Little bicycle tires and rims aren't very strong sliding sideways, as many find out when they hit something, the wheel does a sideways lurch, and gets a little wobble in it when it regains traction. This has happened to me enough times that, together with not wanting to fall, I'll do anything not to lose traction.
A short wheel based racing bike will go around a corner really fast. Leaning the bike over--as far as you dare!--will scribe a tight radius in the turn, while the weight of the rider, directed down on the outside pedal, will hold the wheels firmly on the ground. That's how to get around a corner on a bike, mate. Forget about sliding.
Jan 30, 2002 1:36 PM
|I've done the back wheel slide on a road bike (wet surface)...catching it and not going down is pure luck. My theory is that under most situations road bike tires break away so dramatically that you are either up and railing or or you are down and flailing. Full grip or zero grip. Very little in between, no progressive slide.|
Jan 30, 2002 4:05 PM
|I have experienced some serious two wheel drift on the MTB; but that is a completley different subject.
On the road in a race I have got to the point where I can feel both tires drifting ever so slightly without going down (accompanied by a rubber chewing sound); but that was on a smooth consistant surface with no gravel, painted stripes, bumps etc.. It seems that you go down like your on ice when you slip on a patch of gravel paint etc.
I once had a wicked slide out on a downhill curve. I ran over a rock just after attacking. I was going in the 30's and my rear tire snake bit and went flat immediately. I got on the front brake and never touched the rear, but the back end gradualy slid out as I flew around the corner. I was close to completely sideways when I finaly got the bike to stop and the peloton roared by. A few of the guys in front got to see the whole thing and said they thought I was going down for sure. I was too tired to care though.
|cornering limit||peter in NVA|
Jan 30, 2002 4:21 PM
|I skid my front and rear wheels all the time with my cross
bike in mud - its basically a road bike with little knobbies. I can usually control any kind of skid, even very loose gravel, it the speeds are slow (15 mph). You should try it to get the feeling. I can usually anticipate when the wheels are going to brake away by reading the terrain.
However, I almost always have crashed on my road bike when I skidded because it was unexpected and everything happened so fast.
|what i tried||Woof the dog|
Jan 30, 2002 6:32 PM
|as others have said, it is pretty much impossible to recover from the front slip where you go beyond a certain threshold and your tire slips from under you. The rear, pump it up high, will slide lots better even under not much leaning angle. Anyways, I was once cornering like a dog i am, and I felt that my front tire (specialied turbo team either 20 or 23 c) started making a squirming sound. It has this edge that I assume was bending in. I was definitely leaning real hard. I laid off of the lean and came out just fine. For that you certainly need a dry pavement. I also crashed at least twice with a rear wheel slide out. I don't know about you guys, but at max leaning when something goes wrong (and it did for me), its pretty hard not to crash. It happened both times on sand and/or dirt. Funny how the front one didn't slide while the back one did. Happens very fast and bam you have this spot on your thigh for the next two years. brrrr, another reason why I don't shave all of my hair under the shorts. With dogs like me, you can actually slide on your hair to a certain point. LOL
Woof, the sliding dog.
|re: Riding bike at cornering limit?||fuzzybunnies|
Jan 30, 2002 8:38 PM
|I have success fully done it in a cyclocross race, a steep downhill with a light drop into a gully and you than follwed the gully/ditch down. First time was an accident the rear wheel shot out from under me I slid sideways till the wheels caught on the far side of the gulley, proceeded to do it intentionally for the next 5 laps. Helped me pick up distance on those people who kept slowing down to try and make the turn. Also did it on road. Street made a sharp(90 degree) turn but was still angled with the down hill. The whole bike skipped 4 times before the tires gripped and the bike shot off down the road. I attribute staying upright to pure luck and 2 day old tires. I've also never tried that corner at that speed again. Russ|| |