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Sunday, May 16, 2010

Track Gearing

The biggest difference between track and road racing is the attitude towards and use of gears. Gearing on the road isn’t thought about all that much, except perhaps for juniors who have to comply with gear restrictions. At any given time, riders commonly don’t know what gear they are in. By contrast, on the track, gears are a precise matter, and gears are chosen very specifically for each event.

As an opening note, track racers talk in gear inches – not teeth. It’s much more precise and frankly easier to say. A roadie at the track is easy to spot because they will talk about gears in terms of teeth rather than inches. If you’re going to get into track racing, it’s worth learning and thinking about gears in terms of inches. To help you do that, I’ll make reference to both systems below.

Track racers invariably use much smaller gears (and therefore, pedal at much higher cadences) than their peers on the road. When Tom Boonen winds up a sprint on the road, he is in a 53 x 11 or 53 x 12, which yield 126” and 116” gears, respectively. If his sprint tops out at 60kph (37mph), his cadence will max out at either 100 rpm’s exactly (in the 53 x 11), or 109 rpm’s (in the 53 x 12).

By comparison, elite track racers commonly hit 60kph, but would never use a gear larger than 50 x 14 (94”), and more likely would be riding a 49 x 14 (92”) or 51 x 15 (90”). So, at 60kph, their cadence is between 134rpms (50 x 14) and 141rpms (51 x 15). To put this in road terms, for an elite track race – say, the World Points Race Championship – the world’s top riders will do the entire race in a gear just a little bit smaller than a 53 x 15.

That’s a pretty big difference in approach. A road racer would never limit himself to a maximum of a 53 x 15 – but that’s what the top track racers do.

The real difference between road and track racing is best understood when you realize that track racers don’t just provide short bursts at 140rpms. Because elite track races commonly proceed at 50 – 55kph (31 – 34mph) for long periods, track racers sustain 120 - 130rpms throughout much of the race, and then accelerate to over 140rpms for the sprints. Hitting 140rpm’s for a sprint isn’t hard – any roadie can do that. Sustaining 120 to 130rpm’s for an entire race (no freewheeling!) and then hitting 140+ rpm’s in the sprint is impossible for most roadies – it takes some training.

So – understandably, when they start out on the track, many experienced roadies just figure that the track racers must have it wrong, and choose an enormous gear (say, a 51 x 14 – 95.5”). That’s what I did. It doesn’t work. After a while, they come around.

So, why do track racers use such small gears? There are probably other explanations beyond what I will offer here. I am neither a physicist nor a physiologist. But I’ll give you my angle on it.

If you’re going into a race with only one gear, you are going to optimize that gear to the most critical moments in the race. But the most critical moments in a race aren’t just the sprints; they are the accelerations, too. The problem with riding a relatively large gear on the track is that it accelerates more slowly (a distinct disadvantage when you need to jump hard to stay near the front), and ramping that gear up for repeated accelerations will burn your legs out over the course of a race.

So, in simple terms, you want a gear that can do two things: efficiently get you through repeated accelerations from 40 to 50kph, and also get you up to 55 – 60kph for the sprints. In a typical 92” gear (49 x 14), when the field is proceeding along at 40kph (25mph), you will be turning 91rpm’s. When there’s an acceleration up to 50kph, you will need to produce 114rpm’s. To accelerate again up to 60kph, you will hit 137rpm’s.

These accelerations are easier to do in a smaller gear than in a larger one. A true roadie might choose a 53 x 14 (99”) for a perfectly flat race where the speeds range from 40 to 60kph. Certainly, for the 60kph sprints, that gear will wind up to a respectable 126rpm’s. But at 40kph, a 99” gear will be grinding along at 84rpms, and at 35kph (22mph) the gear would truly be in slow motion at 73rpm’s.

Now, I suspect this analysis won’t be entirely satisfying, especially to roadies who haven’t tried the track. I won’t claim that this is the whole story – there are surely more and better explanations for why experienced trackies all use smaller gears than road racers do. Other factors may include the fact that there is no freewheeling – so track racers never get to rest their legs altogether between major efforts. Or the fact that it’s harder to get out of the saddle on the track, particularly in the corners of a steeply banked track, so simply accelerating a large gear by standing up and using your body weight for leverage isn’t as easy to do.

In any event, the fact remains that track racers do all use smaller gears. And while Tom Boonen may be more likely to turn a 53 x 11 than a local amateur roadie, world champion trackies are not more likely to use large gears than local amateur trackies. If anything, elite track racers tend to use smaller gears than amateur trackies do.

So, what does track gearing look like in practice? The table below shows a typical selection of chainrings and cogs that a track racer would keep in stock, and the gear inches they produce with a 700 x 23 tire, rounded to the nearest half-inch. For easy comparison to road gears, I have included the gears on a 53 chainring in the far-right column, even though a 53 would be an unusual (though not unheard-of) chainring to find on a track more here

...................also more information on track racing here

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