Tuesday, February 17, 2009

How To - Rock The Bike

Or "swing" as a recent internet post described it. It's what sprinters do when they're sprinting (of course) to the line, out of the saddle, waggling their bike's tail like a bunny on speed.

I don't know if it's maybe a subconscious type of movement. It seems that some riders never think about it, others have to practice it until it becomes natural. It may be like learning how to throw a baseball - some look right the first time they toss a ball, some look positively wrong. Given some practice, though, and pretty much everyone can throw a baseball.

Whatever, ultimately the motion of rocking the bike while out of the saddle is a skill you really must have in your technique "quiver". You recruit and use different muscles and you can ultimately exert more force on the bike by standing and rocking it than you can by staying seated.

The rock is a result of pulling up on the bars (on the downstroke side of the bike) and pushing down on the bars on the upstroke side. Essentially you're holding the bike in place with your hand while you push down. I find the "push down" on the bars is really more of a guiding thing since I don't pull up that hard, but when I feel the need to push down I know that I'm doing a good sprint.

The rock is not an arbitrary thing. You don't do it just because. You do it because there is a reason for each movement. The sum of those reasons makes the bike rock.

The amount of rock is usually relative to the height of the rider. Since most riders are about the same width (to wit - most bars come in 40-44 cm widths), most everyone moves their bike side to side about the same amount. It might be a foot, maybe just over that. This means a tall person is perceived as swinging the bike less because their bike tilts less (less severe angle relative to the road), but in reality everyone takes up about the same amount of space on the road. Even the most "wild" bike swingers (Abdu, McEwen, etc) use up about the same amount of road - it's just that their shorter statures make their bike swinging look so radical.

At some point I realized that tall riders simply don't rock their bikes to the same angle - imagine someone's saddle rocking back and forth four feet on each pedal stroke! That's what happened when I told my 60 (or maybe 63?) cm frame riding friend how much to swing the bike. We were discussing this in college and I used some bars to describe how much to rock the bike. Of course, when he rocked his much taller bike that much, it didn't work out. We later reduced his "rock" down to about 2 feet since, with the full rock, he ended up using so much energy moving sideways.

You can work on the rock by doing it in slow motion at super slow rpms (10-30 rpms) in big gears (53x12). This will allow (and force) you to experience the different elements of the pedal stroke individually and in great focus. I like doing this when warming up and such. It's a lot of fun - I pretend I'm in a NFL type historical clip, you know, where the football is spiraling slowly through the air while the deep voiced narrator describes the significance of the scene. Only I'm on a bike and I'm reliving some field sprint, not some touch down. You can also practice your historical bike throw too, teaching your body to instinctively end your sprint in a throw.

Don't use a lot of pedal pressure, just go real slow. You're going too fast if you can't unclip at any point of the pedal stroke and put a foot down. A skittering foot, maybe, but still, a foot down. No 30 or 40 mph efforts here. This is all drill.

Typical slow rpm movements:

1. Start with the right foot at 1 o'clock (top of power stroke), the bike would be tilted to the right. In other words your left foot is at the bottom and you can see the left crankarm in whole when you look down. The right crankarm is obscured by your top tube.

2. Push down with your right foot, pull up with your right hand, kind of like if you were trying to pull on some boots or tight jeans or just simply pulling something with your hand as hard as possible while bracing your foot against it.

As your right foot drops and you're pulling up on the bars, the bike will start to become more level.

(Note: if you're working on your downstroke only, you could literally unclip your left foot and let it dangle... then clip it into the pedal in time for the left pedal downstroke, alternately unclipping a shoe for the upstroke and reclipping it for the down stroke. If not wearing cycling shoes you can lift your trailing foot off the pedal - say if you're riding your BMX bike down the street. This will teach you not to push down with your trailing - left in this case - foot, i.e. work against your downstroke)

3. As you finish your downstroke your right foot is at the bottom, your bars are pulled up as high as you can pull them, and your bike is now tilted to the left. Repeat on left side.

Bahati (in the front, red toes) is at the top of his pedal stroke, a very aggressive pedal stroke. Candelario (green) is midway through the stroke, his bike is almost upright. Hekman (red jersey) is mirroring Bahati's position. He is throwing his bike a lot - his saddle is further out than his hip but still within his elbows.
(picture is of 2008 US Crit Championships, site is here)

You shouldn't force the rocking of the bike, it should be a result of the pushing and pulling on the bars and the pedals.

The reason why the rock is helpful is that you have a greater range of motion with your upper body. If you hold your bike rigidly upright (and that does have its merits), your muscles are locked in one position and will fatigue relatively quickly. If you swing the bike, your arm will be alternately extended and contracted, allowing you to recruit all sorts of different muscles.

A technique advantage to sprinting out of the saddle is that your bike throw becomes much more significant. A seated rider can throw his bike only a few inches forward, maybe a half a foot. A standing rider can throw his bike forward much more, a foot or more. In close races that can make the difference between a win and a not-win.

1 comment:

No One Line said...

A very cool post - thank you, Aki.

With the start of Bethel being only a week and a half away, I've been experimenting with my sprinting, trying to dissect what it is I do naturally and what else I can do that might get me another mph or two at this point - just from form and mechanics, not from working out. I was playing with when and how I jump and sprint and how low my torso and how flared my elbows and how much I spin and how much I sit back and dig deep, but I think I need to go back out at Prospect Park and play around with throwing the bike.

Rocking bikes is a natural motion to me for a few reasons - one is growing up, riding around the neighborhood on a heavy old mountain bike, it was just the way to ride - jerk the bike back and forth when pedaling was difficult. Same goes for spending a lot of time riding a fixed gear. Even on a low-ish gear, going up a hill still requires some very un-roadbike-ish movement, and the pulling-and-pushing is very similar.

But I haven't carried it over to a sprint, and I think I need to figure that out.

After all, March 1st is very soon.