Friday, February 02, 2007

How To - The Actual Sprint


My only strength is sprinting.

If it wasn't, the blog would be called something other than Sprinter della Casa.

What this means is I spend a lot of time thinking of how to make my sprints count.

I find that I focus on particular things when planning my approach to an upcoming sprint. This is assuming I'm in position to contest an upcoming sprint, i.e. I'm still in the race. If I am, I think about the following things (Note: the things I think about are relatively universal, i.e. if you approach sprinting the same way, it should help you too):
1. Gearing
2. Shifting
3. Length of sprint

These have nothing to do with training or positioning or any of the many other factors in sprinting. What it does is focus on the actual sprint itself - when will you start it, what gearing will you use, and the idea of shifting in the sprint.


If I'm being led out (or sitting behind unwitting lead out riders), I typically shift up one or two gears relative to the riders in front, i.e. instead of the 15T, use the 14T or 13T. This suits my strength (power jump). Roadies are typically power sprinters and use their power to muscle the gear.

Since the speeds are quite high in a leadout, it's not unusual to find myself already in the 12 just before the sprint, my legs cruising along, itching to jump. If my legs are getting a bit "slow" feeling, I'll pop up to a bigger cog for a rev or two and then drop back into my "jump" gear.

Because approaching a sprint is rarely a planned thing, you can't really plan on your final sprint gear. It might be the case that a fanatically committed team leads the sprint out and you're hanging on in your 11T. Or everyone looks at each other with 500 meters to go so you're cruising in a 15T. However you can think about your actual sprinting gear with a +/- 1T range for wind, tired/fresh legs, optimal/non-optimal jump, etc.

Regardless, you need some rpm headroom for your jump. In your car you don't downshift to accelerate from 6000 rpm if you have a 6500 rpm redline. Instead, select a gear that allows you to accelerate from, say, 4000 rpm up to redline. This is assuming some factors like you have enough torque at 4000 rpms and stuff. But I digress. It would do no good to jump at 140 rpm when you make more power at 120 rpm. Instead, it would be better to jump at, say, 110 rpm so that you spend a lot of time in the meat of your powerband and then start to sprint out of it before you shift up to the next gear.

One requirement to execute is you have to get to the beginning of the sprint reasonably fresh. If you've killed yourself simply to get into position, you won't have the boost necessary to launch you to the finish. This is my take on Zabel's sprint performances.

I have helmet cam tapes (from a cam I wore on my helmet) which I watch when I want to psych myself up. Two things surprise me. One is how far apart everyone rides. The other is how much faster I go in the sprint versus any other time in the race. Even the relatively hard moves to get into position pale in comparison to the mic-flooding rush of wind produced when I launch into my final sprint.

When one talks about gearing and sprinting, one can always debate the advantages of spinning versus powering a big gear. Trackies typically use much lower gears and still hit incredible speeds - 43 mph is not unheard of with a 51x14. Mark Whitehead (a great trackie) and Davis Phinney once met head to head in a sprint on Phinney's turf, a criterium. Whitehead was spinning a 53x15 with sewing machine like legs while Phinney churned his 53x12. Since it was road turf, the Phinney's power sprint won in the end. As a general rule it is easier to power a big gear at a certain speed at the end of a long race rather than spin a smaller gear. As long as you don't go too far over 120 rpms in road sprints you should be fine.

Moral of that story? You can work on your spin sprint but on the road you absolutely need your power.


Once you start your sprint, you must be able shift any time you like. If you can't sprint at 100% and shift at the same time, you might as well put downtube shifters on your bike.

If you've installed and adjusted things properly, your drivetrain can take a full on shift (out of the saddle, no easing up, no thought to when to shift). It might be loud or unsettle your bike (or in the old days jerk your foot out of a triple-binda set so tight your toes turn purple) but your bike will shift. In the old days I used a single right-side bar end shifter and chopped my bar so the shifter sat right in the palm of my hand.

If shifting under full gas you may unclip, skip your rear wheel, wrench your bars if not tightened, bend them if you're really strong, etc. It's critical to practice shifting while sprinting before you do it in a race. You don't want to learn in the middle of a big field sprint that your derailleur wasn't adjusted quite right as your chain jams between your 11T and the frame. I've had to crank my pedals down a little more than normal, to the point where I can't unclip with just my foot - I have to hit my shoe with my hand to unclip.

I use Campy Ergo levers set relatively low on the bars. If you have your levers up high (like a climber) then it'll be virtually impossible to shift from the drops while at full gas. The reason? You have to move your hands up to shift. If your levers are optimally placed you'll have access to the controls while you're sprinting.

I see a lot of riders set up their levers so it's "comfy" when you're riding on the hoods. The problem when it comes down to a sprint is that you don't ever want to sprint from the hoods. You lose power, control, and braking ability. Drop your levers down so you can shift from the drops without any contortionistic maneuvers. You don't have to get SRAM levers to shift in the sprint - just put the levers you have now in the right place.

Length of Sprint

A long time ago I read that a human body can sprint (at max effort) for 40 pedal revolutions. I took that as gospel and followed its implied message ("You'll cover the last bit of the race fastest if you sprint for 40 revolutions"). But during long trainer sessions watching race tapes of big field finishes, I counted the pedal strokes the Tour sprinters did once they jumped into the wind. Surprisingly I found most of them did only 8-10 strokes in the wind in the stages I checked. The exception was the final stage when they inevitably went about 20 revs. I realized afterwards that the Champs Elysee finish is a slight downhill sprint so sitting on wheels is less advantageous.

One of my best sprints ever was one where I committed to going at about 10 revolutions to go before I even got to the race. The venue was one of my "target races" (I have two or three a year) so it was pretty important to me to do well. I hadn't managed to break into the top 5 or 6 but always seemed to be around 10th so I knew doing better was possible. Normally I wouldn't go to a target race and radically change my approach but since I'd been doing the race a long time I figured I had to change something. I picked out a landmark which was about 10 revolutions from the end and decided I'd gamble and go very late in the sprint.

The race went reasonably well and it came down to a big field sprint. I waited for what seemed like an eternity as racer after racer launched into their final sprint. I grimly hung on about 10 or 15 riders back and waited for my mark. In the end I probably went a revolution early but did a spectacular sprint and threw my bike for third or fourth.

Could I have done better had I gone earlier? I think so. I think Tour racers have so little left after four hours finished off by a very fast run in to the sprint. The pros can't afford to go too much earlier because they're used a lot of their reserves before 200 meters to go. I, on the other hand, have much more in reserve - I'm probably still flush with carbs and stuff and not starting to get those weak, dizzy spells I get after being on the bike for 3 or 4 hours.

With the 8 or 10 revolution sprint out of the way, I now go a bit earlier in general. I do try and limit my sprints to 20 revs or less, and unless I flub my position going into the sprint, I've been successful. At a new race venue I'll ride backwards from the finish in the gear I think I might use for 20 revs, find a landmark, and try and be in good position at that landmark. Wind, legs, and lead out determine the final gear but after a lot of sprints and a lot of racing, I have gotten good at figuring out a base gear for the sprint.

Now if you are sprinting against me, all these things don't apply. Go from 40-60 revolutions out, sprint on the hoods, and jump and stay in your 12T.



Jim Thompson said...

Hi Aki,

Please tell me more about your helmet cam.

Have you posted any video to website?

Go Fast ... JIM

Aki said...

I haven't posted any video to the net but want to do so.

helmet cam is three parts:
1. Camera on the helmet from, 520 lines. (No I don't get anything from them but they are an excellent service oriented company). It's an actual camera with a fixed focus lens (works out to infinity).
2. The ChaseCam feeds into a Canon ZR100 camcorder (which records in VCR mode from an external source). Given the choice I would have gotten a camcorder that allows remote recording start/stop.
3. The third part is the "accesory" list needed to run all this:
- 8 AA batteries to power the ChaseCam
- wiring to connect ChaseCam to camcorder
- CamelBak to hold everything (no bladder)
- mount for ChaseCam (adapted helmet light mount)

I use rechargeable AA batteries.

1. Camcorder - Approx 80 minutes with stock battery, IDK with new battery (2 hours = 1/4 used). Longest tape available is 80/120 minutes (so 2 hours in LP mode).
2. ChaseCam - 10-12 hours on the AA batteries. I've recorded two races weeks apart without charging the batteries.

There are some other details but this is the basic setup. I think I'll have to post something a little more detailed (pictures etc) on the setup.

Anonymous said...

Hi aki, great articles on sprinting. I have never prcticed in any methodical way like you describe, but now I want to. Do they still do the Purchase ride? do you have the video from yesterday's finish in wilton?

Thanks, Doug

Aki said...

hey doug

you can definitely get more out of a sprint if you work on specifics and take advantage of all the technical advances made in the last 10-15 years (ramped teeth = shift under pressure, Ergo/STI levers = shift while sprinting, clipless pedals = shift while sprinting).

Purchase sprint rides ended 10 or so years ago after a runner got hit by a car at the same time the sprints were happening (runner was about 1 mile from the group). The school decided it was too risky to allow the sprints there and shut down the ride.

I am experimenting with a Firewire (I'm a bit behind the times) to bring the tape images of the finish to the computer. I'll post when I figure this out.