February 2008 - Posts

Faster #6 - Cadence drills
29 February 08 09:07 PM | ericgu | with no comments

To travel at a given speed, you need to put out a given amount of power. You can either do that by pedalling slowly and putting a lot of pressure on the pedals, or by pedalling faster and putting less pressure on the pedals.

Since the more pressure you put on the pedals, the faster your legs get tired, it's preferable to pedal faster. Within reason.

First of all, there is a limit to how fast you can comfortably pedal. And second, spinning generally stresses your aerobic system more, so you can run out of breath more easily.

So high cadence isn't somewhere you always want to go, but it's a useful tool to have in your arsenal. And if you can ride smoothly at a high cadence, you will be able to ride smoothly at a lower cadence, which is a good thing.

You may have come across suggestions to aim for riding at 90 RPM. I'm going to make a different suggestion. If you are willing to work at it now and then, you can expand your RPM range all the way up to 120 RPM, and beyond.

To make good progress, you need to do focused drills that will work on your speed. Here's the one that I like to do:

1. Start at a comfortable cadence and a middle amount of pressure
2. Over 30 seconds, gradually increase your cadence until you reach the point where your stroke becomes jerky or you start bouncing
3. Back off the cadence slightly until you are smooth again
4. Continue for 30 seconds
5. Slow back down to your original cadence

Repeat this a couple of times, and you're done for the day. The next time you get back to it, extend step 4 to a minute, and then ultimately aim for 2 minutes. You are retraining your neuromusclar system, and it will take a bit of time to do so, but over time you'll smooth out again. Initially you will be a bit inefficient at this, so you might get out of breath. You can deal with this by going into a slightly easier gear, and over time it will get easier.

On normal rides, spend some time at a higher-than-normal cadence, but don't try to push up your whole limits.

You don't need a computer that supports cadence to do this, but it does help. With doing these now and then, I pushed my top cadence from 105 RPM up to 120 RPM, and on a ride last year I held 145 RPM for about a minute while pulling at the front of a paceline on a slightly downhill.

Rating: Good stuff. Will make you faster, but most importantly, will make you smoother and impress you're riding buddies.

 

Filed under: Faster

Faster #5 - Specificity
25 February 08 09:17 PM | ericgu | with no comments

Initially, you just start riding. Perhaps you're doing it for fitness, or to lose weight, or just for recreation. And then, at some point, you decide that you want to get a bit more serious, so you start riding a bit faster, riding a bit farther.

And then you plateau. You're riding harder, but not getting any better.

The problem is that you're riding "sorta hard".

A bit of digression into training theory...

The purpose of training is to impose training stress on your body. The stress triggers your body to get better during recovery. But when you're riding sorta hard, you aren't riding hard enough to put a real training stress on your body. That's why you plateau.

The way to get beyond this is to add specificity into your training. Rather than trying to work on all aspects of your riding - on all the energy systems that go into being fast - you work on them one at the time.

Or, in other words, your training is *specific* rather than being general. You might be doing:

• Intervals, to stress your anaerobic system hard
• Long steady rides to build up your aerobic system
• Tempo work to push up your aerobic threshold
• Muscle tension to improve your strength

And, you'll be sure that you're recovered so that you can get the full benefit from the hard workouts.

The disadvantage? Well, you have to have focus, and you have to work to fit the workout you want into group rides (if you go on group rides)

Speed Improvement: High
Coolness Factor: Low (this isn't very sexy stuff)
Cost effectiveness: Epic. At most, you need a book, but you can get by with what you read on the internets.

Verdict: One of the best ways to improve your speed, if you can stick to it.

Filed under: Faster

Faster #4 - Ceramic bearings...
09 February 08 09:34 PM | ericgu | with no comments

Ceramic bearings - bearings with ceramic balls rather than steel balls - are a common choice by the top-end cyclists. So, how much do they really gain you?

If I can, I try to figure out what sort of maximum gains you might see when from a specific increase. In this case, we can do a decent job, as we know roughly how efficient bicycles are.

The best data that I've found suggests that modern drivetrains are about 95% efficient (though it's hard to know exactly what they're measuring). If we could get rid of all the lost, it would be like we increased power by 5%. So, a climb that took us 10 minutes would now take:

600 seconds * 0.95 = 570 seconds.

Which seems like an impressive difference.

Though, from a speed perspective on the flats, it's not as big of a deal. 5% more power takes us from 15 MPH to 15.3 MPH, or from 20 MPH to 20.4 MPH.

But, we're not going to get rid of all of that - there's still some loss in the chain.

Cyclingnews did an article a while back on SRAM's $190 bottom bracket that claims that it reduces frictional losses from 4% to 0.5%. Note that that also includes some other low-friction design changes and a low-friction grease. That's gets you up that 10 minutes hill about 21 seconds faster.

On the other hand, Zipp claims that you get 2 watts at 25MPH with their ceramic wheel bearings. The handy Speed and Power Calculator estimates that 25MPH requires 300 watts with hands on the drops, which means you're saving 2/300 or about 0.6% of your power. Not really a lot of savings there, though presumably you could save that much for each wheel, and gain a small amount of speed. They do note that the savings against the high-quality steel bearings they use on their other wheels is only about 1 watt.

We can also assume that both SRAM and Zipp are using the best ceramics they can find in their bearings, and there are very likely cheaper bearings that are going to have a lesser surface finish and therefore far fewer gains. I'd be especially leery of the improvement from other ceramic bottom brackets because my guess is that the seal design and lubricaton are significant factor, especially given the big difference in gains from using ceramic bearings between the bottom bracket and wheels. As for cost, I've seen 5 bearing sets for Mavic wheels for $300. Or, you can find a set of bearings for $35 on ebay.

In other words, buyer beware. Those ceramic bearings you saw on ebay may not be any faster than the ones you're currently using.

Speed Improvement: Medium (pretty good for a hardware change)
Coolness Factor: High (all the pros are doing it)
Cost effectiveness: Low

Verdict: The bottom bracket looks nice, but yowsa, those parts are expensive. But, probably a better use of funds that that titanium seat post bolt you were thinking of buying...

Filed under: Faster