BananaBikeRIP said:
.... Surely you have to turn slightly in to the curve so the centrifugal force pushes you out? I may be dangerously wrong....Also, any advice on what to do with the brakes under these circumstances?...
There are a lot of reasons your back end can kick out a bit during hard cornering and it doesn't always mean a crash is coming but there are things you can do to minimize wheel slip in corners and things that will likely make it worse.
- Put most of your weight on your outside pedal with the pedal at the bottom of the stroke. If you're a skiier, think of weighting that pedal like you might weight your outside ski on firm snow and carve through the corner with most of your weight on that outside foot.
- It also helps to slide back a bit in the saddle and make sure you're weighting the rear wheel. A lot of folks creep up to the tip of their saddles when cornering on fast descents and that can cause problems if you end up with too much weight committed to the front wheel and not enough on the rear. When in doubt, and especially if you're having trouble with the rear wheel losing traction make sure you slide back and put extra weight on the rear wheel.
- Corrective 'steering' as in noticeable steering of the bars is a really bad idea in any high speed cornering situations. It's not like a car sliding on ice where you can actually rotate the steering axis of the wheels by many degrees and turn out of the skid. Try something that dramatic on a bike in the best of conditions and you'll crash but definitely not when things are slipping and you've got to react quickly.
- On the other hand 'counter steering' a technique borrowed from motorcycles can be real helpful for hard cornering and can make fast bends, especially on mountain descents feel very tame. Visually it won't look much like steering at all, but basically when cornering say to the right you'll have your left leg straight down bearing a large percentage of your weight as described above, you'll still want to be weighting the saddle quite a bit and possibly slid a bit back and not creeping up to the tip, but you'll be putting extra pressure on your inside or right arm into the handlebars. It won't be visible as a turn in the wrong direction, but that's basically what you're doing, putting extra pressure on your inside hand to cause the front wheel to angle very slightly the wrong way for the corner. It drops your front end a tiny bit and carries you around the bend like you're on rails and goes hand in hand with the carving of the outside foot. You can do it while riding the brake hoods or drops, but it typically feels the most solid from the drops and that's where you should practice it starting with just a tiny bit of extra pressure and playing with it to see how it feels and how it helps you corner more safely at high speeds.
- There's upper body involvement in all of this as well and again it borrows from skiing. Basically your body shouldn't form a straight line from your pedals to head as you bank into the turns. Ideally you break or 'angulate' a bit at the hips so that your upper body is more upright than your lower body. Think of pressing the bike and lower body down into the turn while staying relatively upright with your upper body. If you alpine ski you'll know the feeling, if not play with it and see how it helps you sweep from curve to curve on a twisty descent with more control and without the dramatic side to side motions of your upper body. This also helps in your roundabout situation where it becomes a lot easier to pull your bike back up a bit straighter mid corner if your upper body isn't heavily banked and committed to the inside of the turn.
- Try your best to do all braking before you enter the tight part of the curve. Sudden braking mid curve is a quick way to lose what traction you have and have one or both wheels slip out. If you must brake into the curve then try to feather the brakes just enough to control your speed and let go of the brakes as soon as you see your straight line to exit the corner. And if your rear wheel is already sliding then definitely don't use your rear brake at all or the wheel will slide out completely.
- There are body english tricks you typically learn through off road riding like cyclocross where you can do different stuff like keep the bike mostly upright and actively steer the bike through tight corners. These are tough to describe but not too hard to learn on a grassy field and can save your butt when things start sliding allowing you to straighten your bike up mid bend if the rear wheel starts to slide out but you'd better be good at this stuff if you don't want to ride right into the oncoming lane if you need to change lines mid turn.
- Watch out for bumps, potholes and steps in the level of the pavement that can cause you to lose contact with the pavement for a moment while you're in mid turn. That happens in some races and it's not unusual to see wheels kicking out every time the field passes through the corner with the uneven pavement. Pedaling high rpms while tipped out on the saddle and 'riding the rivet' makes this much worse. So pick your lines if you can and make sure you're weighting the rear wheel in sections that are prone to wheel skip.
- There's also the equipment aspects, some tires corner better than others on wet or dry pavement and proper tire pressure can help keep you in contact with the road.
Anyway, good on ya for not panicking and locking up the brakes. That would have put you on the pavement for sure. But the best thing is to figure out how fast you can corner in different conditions, improve your overall cornering skills, make sure you're riding tires that corner well for the conditions you typically ride, make sure your tires are inflated properly before riding and try to enter the curves at an appropriate speed for the conditions.
Good luck,
-Dave
.
