Sunday, June 14, 2009

Go faster stripes

I like time trialling because it feeds my numerical obsession. But sometimes it can be confusing. Pinning down why you're fast on a particular day when you're not on another should be a matter of power and aerodynamics, but sometimes there are things that you can't explain easily.

I've done two 25 milers in the last week. Both were largely on dragstrip-type dual carriageway courses, both had a moderate amount of traffic and wind, similar air pressure, and I averaged exactly the same power for both (314W).

One was the nationals, where I did 54'49 for 43rd. The other was the Dursley 25 on Saturday evening, where I flew around to win in 50'49 - a new personal best and club record, and I think the second fastest time ever on the U46B (Richard Prebble has done 50'02 on it). Interestingly, my old PB of 52'02 was set on the same course last year in June with almost the same power output (315W).

The other interesting thing is that I put 1'30-1'50 into riders who beat me or finished close to me at the nationals. Had I done that in Norwich, I'd have been top 15. So there was a relative gain as well as an absolute one, but for no extra power. What gives?

Some of the absolute gain is explainable. The nationals course was about 0'30-1'00 slower because of the two sets of right hand turns and the roundabout that I had to slow for each lap 'cos of traffic. Plus it was a headwind/tailwind at the nationals and about 12 degrees, whereas it was a crosswind and 18 degrees in the Dursley event. Crosswinds are faster when you've got an aero frame and disk, 'cos of the sail effect. What's that worth? It'll have to be another 2'00, but I suspect I'm being generous.

I made a couple of equipment changes too: I pumped up the tyres to ~140psi instead of ~110 (only good if you've got good roads). I finally got to use my newly purchased Zipp 808 with a Planet X FMB tubular on it - definitely quicker than my usual Zipp 404 + clincher. The tyre/wheel combination makes a lovely singing sound as you ride along. Unfortunately it didn't drown out the song that was going through my head: Hit Me Baby One More Time, by the much misunderstood chanteuse Britney Spears. Don't ask me how that got there 'cos I don't know.

I also bought a Specialized aero bottle, which although it was tilted to one side probably provided a bit of a fairing compared to a normal bottle. I got some new Pearl Izumi shoe covers - a bit better than my rather tatty lycra ones. And I mounted my computer on the top tube, which was more aero but resulted in a bruised left knee 'cos I kept hitting it on the upstroke. Bit of a fail there.

Finally I was riding in new shoes and had abstained from alcohol for a whole week. Shocking I know. But neither seemed to affect my power output, which is a Good Thing.

So that's the other 1'00-1'30 in absolute and relative terms. Well, it'll have to be.

Pacing wise, from a power perspective I was about the same in the Dursley as I was at the nationals. Speed wise, I seemed to get faster in the Dursley despite dropping power, so I dunno what was going on there 'cos the traffic would have been getting lighter towards the end of my ride (I started at 6pm, finished at 6:50). But I do remember in the first 8km I was getting used to riding the 808 at speed (it's deeper so it wobbles more in a crosswind), so would have been putting out more power than necessary. On the second lap I'd figured out how to stop it moving around so much.

My splits were nice and even: 10miles/16.1km in 20'18, 12.5miles/20.1km in 25'25, 15miles/24.1km in 30'34, 25 miles/40.2km in 50'49. So the last 10 miles was about the same as the first 10, allowing for the standing start.

It was nice to win against a full field anyway, and points to some faster times later in the year. Also good to see Robin do his first race for Chippenham (54'06), as well as 13 year-old Luke Davies knock four minutes off his best to clock 1'05'14. He reckons he's raced six times in the last eight days, so it's obviously knocking him into shape.

Next up: the Dave Lloyd Mega Challenge next weekend (jeez I hope it doesn't rain again). It's now 240km and finishes at the top of a steep hill. Plus I'll have to ride to Wrexham station afterwards, so it could be a 270km day.

The weekend after that, I'm doing a 50 mile TT (a similar course to yesterday's 25), then the next week a 10, again on a similar course. The aim is to go under 20 minutes for that 10...

3 comments:

marty said...

Dun good. An even nicer sensation for the aforementioned #'s man? Seems likely the whole notion of quantifying performance by numbers is more deeply entrenched by your scientific training (as opposed to an academic life focused on the Arts, or no academic life). But me thinks that something happens that is nothing to do with scientifically measurable things each time we feel we can shine, we (perhaps unconsciously) permit ourselves to be in a fearless flow, and our "full force" is exposed. (Yeah, I know I'm convoluting the obvious, it's oft and "simply" called confidence).
One of the great things about the race of truth, is that once you get out of your own way, no one else can obscure your performance.
The immeasurable, indefinable energy aspect in conjunction with those 315 watts has all the positive elements aligned (which is a much bigger factor than we sometimes allow ourselves to feel), versus 315 watts with wasted energy trickling down in between the positive and the negative, swirling into a self canceling nothingness, furthering its source.... deleterious doubt? OK, and the faster swirling of the 808's? What frame? Pic's? Marty
Hey can you shoot me your shEmail address, something else I wanted to have a quick yarn about.
chasesyney@gmail.com

Jeff Jones said...

Marty, there is much in what you say. It's not just the numbers - although that does make it easier to measure performance. It's about going *fast* and that is something I have learned to do when racing. It's putting the power down smoothly during the pedal stroke so you keep your momentum going for the least amount of effort. It's getting into the right tuck so you feel like you're invisible to the wind. It's concentrating on going fowards rather than looking down at your power meter.

My power/pacing at the Dursley 25 and the National 25 was almost identical. As was the guy's who I beat in the Dursley but who beat me by 1'40 at the Nationals. I had better equipment (808 + faster tub, aero bottle, computer on the top tube) at the Dursley but I also knew the course and had the right mindset.

Going fast is fun!

Jeff Jones said...

Pics at the nationals (no 808 on):

http://www.sarahbrookephotography.co.uk/photo2752721.html

and
http://www.sarahbrookephotography.co.uk/photo2752722.html