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Club 10 Result 3/8/16

edited August 2016 in Time Trial
18 riders were out this evening and faced a strengthening SW wind. 2nd claim rider Bryn clocked 22:14 for first place on the night which was more than 30 seconds faster than his previous best. Emma was first lady with yet another impressive PB. Felix was top junior and best Vet on standard was Stuart who was also fastest CCA rider.

Thanks Steve, Martin and Robert for organising, and Clare for help with refreshments - results below

Main result

Handicap winner with a 2:55 PB was Adam and can get a free ride next week.

Handicap result

Comments

  • Thanks to all for making this happen. Surprised by the PB this evening given the wind but obviously pleased.
  • Thanks very much to the helpers!
    Technical question for any budding power analysts: last night as I had been expecting to marshall till the last minute, I rode my road bike, without any aero bars - unsurprisingly given the wind, bike choice and massive buffet lunch, it wasn't my quickest time, albeit pb for a road bike. However, my average weighted power reading (using same power meter, fairly consistent) was about 40watts higher than my course pb that is getting on for a minute faster than last night - what does this mean?:

    A)my position on the TT bike is too extreme/aero, and I can produce more power on road bike, but this is compensated by less frontal drag, so TT bike still faster? How much difference in wattage would you expect between an aero position on a TT bike and 'normal' drops position on a road bike?

    B)does fighting a headwind cause you to produce more power? If so why can't I produce that power with no wind, and just go faster?

    C) did the big lunch give me plenty of fuel but make me too fat to be aero..?

    Thanks in advance,
    Dave.
  • Very interesting question. I had assumed that one of the advantages of a TT bike was that it allowed you to get into an aero position, AND into a position that enables you to produce more power? I'm thinking about all of this at the moment as I consider getting a TT bike. I have a decent aero position on my road bike, so what advantage will getting a TT bike bring me? As an experiment, would you consider using TT bars on your road bike some night, perhaps with your good wheels, to make things equal?
  • James, I don't suppose you or anyone else picked up a small black cotton purse with a blue tag, containing a few cards and some cash, maybe on the sign-in desk? I was waiting for it to come out of the washing machine with my skinsuit, but it wasn't there...
    thanks!
  • I'm no expert but perhaps just looking at your overall average power for the whole ride doesn't tell us what's really going on - i.e. ideally we'd need the average power for each leg (out tailwind and return headwind).

    My best guess is that:
    1. You did put a lot more power down on the return headwind leg.
    2. This was offset by a lot less power on the out tailwind leg.
    3. An aero bike should have a much bigger positive effect in headwind.
    4. I see no reason why you shouldn't be able to put down the same amount of power on either bike.
    5. Stuffing your face at lunch probably ain't gonna help either way!

    I really struggled in the headwind last night, and I suspect my strategy of going out easy-ish on the tailwind leg caused me to lose too much time - that I couldn't make up on the return (especially on a road bike with a position that isn't that low).

    Would be interested in thoughts of those on TT bikes - especially Robert who absolutely smashed it yesterday!
  • Good question Dave which I am sure will generate a lot of response. I have been wondering the same thing. So here are some of my observations for what they are worth.

    I only have a road bike. My best power reading this year came from the first TT I did start of season. Nothing aero apart from being on drops throughout but with horrible winter tyres. This has been my slowest time. Since then I have made gradual improvements most weeks but power has never matched that first week.
    I have just out of interest tried to add something pointy or slippery most weeks.
    First thing to go was the tyres then added Clip on TT bars. These 2 things separately gave biggest leaps. But have also added over shoes, pointy hat, no gloves (read that was better?) Last nights effort was another PB and the secret weapon this week - shaved legs = 19 seconds???
    I tried a disc wheel on the back for 1 out of 2 25's that I did on the Guilden circuit a week apart and the disc was faster by 40 seconds. Will try the disc on the 10 soon.
    I think possibly the bottom line is that there are always too many variables to be able to make real sense of this. The maths surely says same power but more aero = faster. I suppose it is partly weather you are able to produce the same power in the aero position. I know I don't really feel as comfortable in the TT position as when riding the road bike normally. I have tried Jack's TT bike and that is far too extreme for me. I guess if I practised more TT style I would see gains?
  • TT bike with a decent position disc and deep sections will always be faster than a road bike. You probably ride the road bike more so are more comfortable on it and the position will allow you to put out a little more power. Most people drop power a little on the TT bike due to having a different position or not riding it as much so not used to using your muscles in the same way. My power is pretty much the same on both, maybe a couple of watts higher on the road bike... Either that or it's all in the head. Some guys go remarkably quick with very little power because they have a very fast position... Time for some #justinfacts I do believe.
  • edited August 2016
    There is definitely a trade-off between power vs position irrespective of all the other aero gains that can be made which would tend to be more marginal. I would very much agree with what Will has posted.

    In some ways the faster you go the harder it is to apply power (not true, of course if all other forces remain constant). During Chris Froome's super aero descent from the Col de Peyresourde at 45-60mph he was only able to apply a small amount of additional power from pedalling (my guess 50 -100 watts at best), although this enabled him to move ahead of the rest of the field who mostly relied only on the force of gravity. Contrast this to the ascent at around 12-15mph where output would have been constantly in excess of 400 watts. All this helps to explain, Stuart, why your power has dropped as you have developed aero gains.

    Tim, your strategy was fine as "A fundamental truth about time-trialling is that they are not won by going fast but by not going slow" Graham Obree. Simple maths tells us that on an out and back course with a wind in line with the course you will spend longer going slow against the wind than going faster with it therefore more time will be lost by going too slow into the headwind. It would seem that your somewhat less aero position meant your speed dropped dramatically.

    The outleg is 3.2 miles and the top road to Wrestlingworth is 3.6 miles. A 2mph deficit at say 28mph on the outleg would equate to about 31 seconds but at 22mph would be a minute for the return. Having analysed various rides from last night it is likely you only lost about 70 seconds in the Easterly direction but a whole 2 ½ minutes Westerly (to the top rider who’s power was 11% higher into the headwind – others that I looked at were only 3% higher) .
    Amongst everything else pacing strategy plays a massive part in determining the overall time to get round any given course.
  • Thanks gents, all very intriguing, everyone raises some good points...

    Brendan - just from what I've seen, I think the ratio of emphasis on aero to power-producing position depends quite a lot between different manufacturers - some companies bikes seem to be purely aimed at getting the rider in a low position, whereas some examples like the Canondale Slice seems to have a more upright position - from reviews it appeared slower than others, but more comfortable, so better for producing power over longer distances. I'm guessing that may be more similar to triathlon-focused bikes that aim to provide a position that allows the rider to be able to run a marathon after the bike leg without crazy muscle spasms....

    If you believe the marketing (and probably some science), a TT frame should cut through the air better than a standard road bike - I have felt mine was a bit quicker in a headwind, and it certainly is quicker than the road bike with bars used to be - not sure how much of this was down to a slightly lower position on the TT bike. I did used to put aero bars on my road bike, as you suggest (although not with the good wheels) - and the improved position bought me about 1.5-2mph on the old course - about the best improvement you can get for the money! Sadly the aerobars won't attach to my current bars, so I can't try it again with the wheels...

    Tim - interestingly, the difference in power on the in/out legs wasn't as much as I'd expected - on the out (turn 1 to turn 2) it was 260w (27.6mph), compared to the in (turn 3 to turn 4) at 275w (21.2mph) - it felt more of a difference! compare them with my course pb on a fairly calm night 226w (25.9mph) out and 228w (23.5mph) for nearly a minute quicker on the TT bike. As Stuart says, though - there's a lot of variables involved!

    Will - I think you're probably right, too - I don't train much on my TT bike, and its really noticeable that when I do get out on it at the weekend, I almost always get a PB on the Wednesday...
    However, I do still wonder if my position is too low to generate the most effective power - certainly my bike fitter on the road bike was concerned that with limited hip flexor movement, going into too much of an aero tuck would compromise my pedalling power.

    I found a really interesting book (if you're a bit of an anorak) is Training and Racing with a Power Meter by Hunter/Allen - certainly back's up James' theory - although I hadn't really thought about the concept of it being harder to produce power the faster you go - presumably you'd notice this more on a flat, straight 'out and back' style course, rather than one with four corners and lumps..?
  • Power meter calibrated properly? Having a shift there or it not being zeroed correctly could account for any oddities. That and batteries being on last legs etc..i tend to ride similar powers for both road and TT as i do a fair amount of training on the TT bike.
  • Had a new battery just the other week, and recalibrate every time I change it between bikes (is this necessary on a Stages PM? Not sure what it actually does...) - looked like a fairly normal reading on the way down to the start...
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