Wednesday, April 27, 2011

Racing - Switchback Descents


They inspire thoughts of those Tour de France scenes where the field is flying down some crazy descent, single file, looking like pinballs rolling down a series of zig zagging ramps.

I love switchbacks.

Let me rephrase that.

I looooove switchbacks.

Come to think of it, I love cornering in general, whether it's in a car or on a bike. G-forces make motion exciting, not speed.

Think about it.

If someone offered to take you to 600 mph, that'd be insanely fast.

Until you realize it's just your flight to Vegas, where the plane cruises at 600 mph. It's kind of boring, right? Like you wonder what you're gonna do for 5 hours while the plane covers 600 miles of terrain every hour.

You read, you watch TV, listen to music, stuff like that.

600 miles an hour! That's fast.

But boring.

Hit some turbulence, though, and it's exciting. 50 or 100 feet up and down never seemed so quick or exciting.

I like the take offs and landings too, because you get pressed back in your seat for the former, tugged by your seatbelt in the latter.

G-forces, right? Specifically lateral G-forces.

600 mph, at steady speeds, is boring.

25 mph, if you're careening around a switchback, can be very, very exciting.

Lateral G-forces.

Rider can feel intimidated by switchbacks though - blasting down a hill maybe 50% faster (45 mph instead of 30 mph) than you'd be going on a flat road, diving into a super hard turn that you wouldn't normally see on level terrain, a drop off on the other side of the guardrail... what's there to be afraid of?

"I can fly like an eagle..."
(picture a screenshot from my yet-to-be-done Palomar descent clip 2011)


You need to approach them properly so you can get through them okay. Work backwards from the exit point, where you want to end up. See where you need to be, when you need to be, to get to the exit point in one piece.

And, preferably, with your wheels still on pavement.

Since the approach determines the rest of the turn, the question becomes, "How do you approach a switchback?"

Interestingly enough, when you think of it, downhill switchbacks are just one type of turn. The difference is that you have a higher potential entry speed and you don't slow naturally due to air resistance (because gravity may be greater than air resistance). So in these turns you lose your "auto safety" feature of naturally bleeding off speed.

So, the tricks, which apply to all turns:

1. Look up and ahead.

I may look momentarily at spots on the road so I just miss cracks and stuff, but in general I'm looking either where the road goes out of sight (if there are bushes/trees/buildings in the way) or about 180 deg worth of turn (i.e. a full U turn) ahead. I have to put up a Palomar descent clip - the helmet cam doesn't show exactly how far I look because I also turn my eyes in my head, but it's clear that I'm not paying attention to the immediate 50 meters in front of me in some turns because my eyes are looking further out. In others there's nothing to see (mounds of ground in the way) so my head is pointed at the the "end of the road" in my vision line; that might be 10 meters or so.

2. Know how to turn technically.

Understand that leaning the bike allows you to sharpen a turn; leaning the body gives you more leeway in leaning the bike (i.e. more bike lean available). That's relatively - you're always leaning the bike, but it's the sensation of leaning it a little or jamming your bottom bracket into the ground. Know about pushing the inside of the bar, i.e. to turn right push the right side of the bar forward.

3. Have enough air pressure in your tires.

I prefer higher pressures, especially at the limit. So on my HED wide rims I prefer to run 100-105 psi, not the 85-90 that I see tossed around as appropriate. Lower pressures, to me, make the bike slide more. I had a bunch of scares when I ran my tires at 85-90. Maybe I'm too old school, unwilling to learn, but I'll take a sense of security before a sense of panic. lol.

4. Know your bike's limits, or at least know when you're within them.

I have some idea of when the bike is gonna let go. When I brake I brake evenly with both brakes - when the rear wheel gets light, starts to skip, or gets slightly airborne, I know I've totally loaded my front tire and I'm at my limit (given that I've already slid my butt back on the saddle etc). It's about weight distribution. Ultimately your back wheel does little during braking on a descent except to give you an idea of how much you've loaded your front wheel. To wit - look at those crazy GP motorcycle racers - they dive into turns with their back tire dancing an inch off the ground, then proceed to accelerate out of them with their front wheel doing the dance thing. I'm still working on making the front wheel dance on the bicycle

5. Don't brake in turns if possible.

If you have to, use both brakes or, if it's a bail out all out emergency, straighten up while you brake as hard as possible then get off and turn again. If you're in a group that may not be an option.

6. Take the right line.

Outside inside outside. On switchbacks it'll be single file, or it should be. No diving on the inside because you'll end up crossing another guy's path at some point, if not on that corner then on another.

7. Along that point, think late apex.

Turn in very late if possible. It gives you more options if you overcook the turn.

8. Leave yourself an out.

Unless you're on a closed road, don't be doing stupid things. Don't cross the yellow line, don't go into a turn at 1000% where even a slight miscalculation will send you tumbling.

Some people will accuse me of descending aggressively. Yes, I like going fast. But no, I'm virtually never at that "sliding tire" point. I dive into turns in crits much harder than I ever do on a regular descent.

I generally feel that if I flat, if I'm even marginally lucky, I'll stay upright. I also try and think about where I'd go if I end up with a problem. Usually you'll have to go straight so make plans on what would happen if you went straight right now.

9. Practice turning.

I know that's an obvious one, but what if you don't live on the slopes of Palomar? What if you live in the middle of Michigan, where every road is a straight line?

Practice the technique and specifically practice the lines. You can do this when you drive (if you don't drive then I don't have any ideas on practicing more). Practice looking ahead, late apexes, everything, when you drive. The simple act of pulling into a parking lot or turning left when the light turns green, that's all practice time.

Don't cut across the yellow line, make the white line on the shoulder your turn out point (assuming no cyclists or runners etc there). On sweeping curves, pick a line and stick to it. Try and make as few, if any, steering adjustments. Many steady curves need no steering input once you get into the curve itself - don't be wiggling the wheel like you're on TV.

Exit ramps mimic descending switchbacks perfectly. You're approaching them at high speeds, much higher than you can take the corner. You have to slow to the appropriate speed before you can think about cornering. Then you need to hold a good line. Nice late apex. Think about if one of your car tires goes flat - what will you do then? An early apex doesn't mix with a tire blowout, unless the tire blew just before your turn in point.

Even my 3 mile commute has at least 10 curves or turns, each way, where I can practice cornering (and I do). When I was driving 20 times that distance each way, with actual entrance and exit ramps... well, I got a lot of practice.

Heck, if you want, practice late apexes when you're pushing around a shopping cart. Just watch out for those label-readers around the corner.

So that's about it.

As far as Palomar goes, it's a great descent with a gazillion switchbacks. I only do the descent once or twice a year, yet I feel pretty comfortable bombing down the descent.

I follow my own rules, have gotten worried once or twice (usually for no good reason), and really have a blast coming down the mountain.

It's really the main reason I do the Palomar rides when I go to my SoCal "training camps" - for the absolutely fun descents. Otherwise I could just ride up and down the PCH for 5 or 6 hours at a time.

And the reason why I can do and bomb down Palomar or Lake Wohlford or whatever other descent I may run across is that I practice cornering all the time, even when I'm not on the bike.

That way I maximize my time experiencing lateral Gs.

And, like I said at the beginning of the post, that makes things fun.

No comments: