Wednesday, February 16, 2011

Racing - Junior Gear Limits

Ah, Junior gearing.

When I wanted to start racing, I fell under this strange and unknown rule called the "Junior Gear Limit". I knew about gear ratios. Heck, that's how I got into cycling, calculating the gear ratios for various chainring and cog combinations, trying to optimize the setup for 8 usable gears out of a 10 speed setup.

Meaning a 2x5, not a 10 speed hub.

We're talking old school here, with the emphasis on old.

Anyway, when I started racing, the rules stated I would be limited to a 7.47 meter roll out.

Ehhh, what?

My bike could not travel more than 7.47 meters with one pedal stroke while in the bike's biggest gear.

A quick look at the reference charts showed that I could use a 53x15, coincidentally the same gear my friend and first mentor Ken had on his bike. (Of course this would change if the bike had 700x21 tires - 650c and 24" wheels would require different gears... more on that later.)

Problem was finding freewheels that started with a 15T.

Even now, with cassettes, it's kind of hard to find a non 11/12/13 first cog cassette. Now try finding a 15T. Or 17T.

Freewheels come pre-assembled and were usually not customizable, at least not readily. Shops didn't stock extra cogs for the most part so you got what you got. Plus most cogs were different for different positions. You might end up with 3 or 4 17T cogs before you got one that fit the 4th spot on your freewheel. It was a pain.

Fortunately I'd optimized my Dawes Lightning's gearing using what's now known as a compact crank, a 110 mm bolt circle diameter (BCD) crankset, shod with a 48/34 combo of chainrings.

Combined with a 14T freewheel in the back (14-21 or 14-23 freewheels - I had two), this came very close to the 53x15 ratio. In fact a lot of Juniors used a 49x14 big gear, so my 48x14 was appropriate.

I patronized a shop that was managed by a racer, a Junior no less, and he sold me a bike set up with a nice 53/42 crankset running a 15-21 almost-straight-block freewheel. It ran 15-16-17-18-19-21, giving me the very nice 16T and 18T cogs, incredibly useful at 22 and 20 mph cruising speeds.

A true straight block (one tooth increments) would have ended in a 20T for a Junior. For Seniors it'd have been the knee-destroying 12-13-14-15-16-17, a 12-17, a tiny freewheel that allowed you to replace drive side spokes on your wheel without touching a freewheel tool.

That's tiny.

Just to compare to current gearing, the 42x21 bottom gear is the same as a 39x20. I seriously don't know how we got up the hills back then, but we all made it with a 42x21. The "strong" guys would run a 42x19, wimps a 42x23. One of my (Cat 4) teammates did Mount Washington and begrudgingly fitted a 42x28 "bail out" gear, doing all but the last few hundred meters in a 42x24 ratio because that was his "super low" gear. He ended up using the bailout gear at the steep section at the top and disappointed himself doing it.

Nowadays that'd be considered pretty dumb.

I run a 39x25 by default, bumping it down to a 39x23 for crits. With 10 cogs in the cassette, I can run a pretty tight set of cogs and still go to a 23T. The 25T big cog forces some jumps but the gear, well, I use it a lot on longer climbs or steeper ones.

Anyway...

Juniors nowadays still have to contend with the Junior gear limit. Why?

A lot of Juniors' parents criticize the gear limit. It forces them to use a ridiculously low top gear. It doesn't let them keep up with the massively geared Senior riders. It limits downhill and top speeds.

But it does something incredible for the long term - it builds an incredibly supple pedal stroke. It teaches the rider pedal form without any drills, without any mindless one foot drills on the trainer, no weird exercises.

You just try and hang on as long as possible. So natural for a 14 year old.

As a non-Junior, it's a little depressing watching Juniors progress. First they show up on a ride, wearing baggy shorts (borrowed from dad, or just baggy because they're still too skinny for anything out there). They get shelled in a heartbeat, making you wait (you can't ditch a 14 year old). They spin tiny gears, ridiculous. You run out of breath just watching them.

Then a year or two later, they're still there when the group hits the hills. And their insanely low weight, oftentimes still in just double digits, allows them to spring away when the road points up.

Who cares if you blast by them on the descent, watching them pedal a tiny gear furiously while you soft pedal you 53x11 by them? It still hurts to have to chase for 5 minutes after the top of the hill.

Then the day comes where they're with you to the end of the ride. They're still struggling with the gear limit in the final bit of the ride, where the pace picks up and perhaps there's a sprint. As you roll down the final few straights you may find yourself on said Junior's wheel. They sit and spin an incredibly high rpm, smooth as silk, months or years of desperate chasing now showing in their form. You know instinctively that when you jump they'll be hard pressed to match you, but you also know that it's only because of the gear.

Mano-a-mano, with appropriate gearing, that silky smooth pedaling Junior will annihilate you time after time.

Every single time.

So for all the critics, I say wait a few years. Life won't pass them by, and the best Juniors, the ones that'll "make it" will make it nonetheless.

In fact, I think Cat 5s should have a gear limit, maybe a 53x14, maybe a 53x15, something easily spun out in a sprint or downhill and less than comfortable in high speed (35 mph) bridge moves. This would go a long way towards teaching proper pedal technique to new riders.

How do you calculate a gear's rollout?

As a Junior this becomes critical since it's illegal to race with a gear that's too big (instant DQ - like the 1983 Junior Crit Nationals where the winner was DQed for running a 53x12 instead of a 53x15 - they awarded Roy Knickman, second by a touch, having rolled his tire in the straight line sprint, the National title) and a huge handicap if the gear is too low.

Remember that rollout is related to your tire size.

Measure the circumference of your current tire. Make sure the bike is normal - tire pumped up, no weight on bike. Then mark where valve is on a floor with a line type pattern like a linoleum or tile floor, roll wheel along line until valve points down again, measure in mm if possible.

ChainringTeeth/CogTeeth*circumference = roll out.

Chainring/Cog gives you the multiplication ratio the actual gear gives you (45x12 to use YMCA's example). A 45x12 is 3.75, i.e. the cog turns 3.75 times for every turn of the chainring (or crankarm).

Remember that usable ratio relies on tire circumference. One very good rider in CT, many years ago, got DQed in the state TT. He won by a couple minutes but he'd fitted an oversize tire on his rear wheel. He (wrongly) assumed that any wheel/tire would work with a 53x15 for the limit, but when he went to rollout his rear wheel consistently failed by probably half a centimeter (or some minor thing like that).

He was duly DQed even though he was running a 53x15 because he ran something like a 28mm tire.

What was frustrating about his experience was that he didn't need that - he was so good that he started carrying a spare tire in the TT because he could have a flat, stop, change it (tubular), keep going, and still finish with a reasonable expectation of winning the TT by a minute or so. He flatted one year and didn't finish, and based on his prior multiple minute winning margin he should have been able to change the flat and still win.

Remember that the gear limit really has to do with your tire's circumference.

The gear thing is simply an easy way to refer to a given gear in a language others understand.

Confusing:
"Dude, what's your biggest gear?"
"7.465 m"
"What?"
"Well, it's 7.452 if I use that other wheel."
"Huh? What are you smoking?"

Not as confusing:
"Dude, what's your biggest gear?"
"53x15"
"Oh. I'm running a 49x14. Couldn't find a 15T but I had the 49T ring."
"Oh."

Of course if one is running a 28mm tire, that's a different story. But on a training ride, or talking over lunch, or in a team meeting, gears are fine.

At a race you have to remember to think in rollout terms.

If you're a new rider, regardless of age, consider a mental gear limit. Try to limit your use of, say, the 11T. Or 12T. Or 13T. Or 14T. Spin lower gears while sitting in. You'll get sore in different parts of your legs, especially the fronts of your shins (at first).

But this pays off in the long run. It's why the old school training schedules all had 1000 or 1500 miles of 42x18 spinning on flat roads - to teach you how to pedal.

It's why I do some stupid long rides when I only do hour long crits.

It's so I remember how to pedal.

1 comment:

Danny said...

Aki, I thank you very much for this blog post. It's Dan from the forum, I asked this question there a month or so ago and you came up with the answer I was looking for.

Very helpful!