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A question for the smarties.(6 posts)

A question for the smarties.hayaku
Dec 15, 2002 3:36 AM
Riding a 7% gain for 17km in a time of 1:00.17 starting at 600m, in the same conditions, with the same gear, the same fitness level and same effort... How much weight would someone have to lose to complete the course in 49 minutes?

Everything isn't the same, I have a better bike, lighter wheels and will have been training for a lot longer than my first try but for the sake of mathmatics, wont you amuse me?

I know I'd have to drop a lot of weight but luckly that can be done, I think.

Thanks.
M.
need to know some things...merckx56
Dec 15, 2002 5:55 AM
what do you weigh now? Do you know how much power you made during the last effort?
Power to weight ratio would be the best indicator. going purely by what you have given us, it's really not possible to figure it out. the time gain is around 20%, but the rest of the numbers for the equation are missing.
Some assumptionsLeGrimper
Dec 15, 2002 2:30 PM
Wattage = vertical climbing x weight (rider & Bike)
OVER
time (in seconds)

Speed = Gear Ratio (52/19 X wheel diameter)x cadence

Assume rolling resistance of 70 watts to allow for OTHER factors. Another fixed point.

Therefore if you were 80kg (plus 10kg bike weight all up) and took an hour to climb 7% for 17kms (1190 meters), @17 kph then this is approx 370 watts. 4.08 watts per kg (you and bike). The gear would be something like 39x23 at 58rpm.

Keeping these variables fixed, to do it in 49 minutes would mean loosing 15kgs, and increase of watts per kg to 4.99, speed to 21kph. The gear now needs to be 39x23 at 66rpm, or push a larger gear.

That is a lot of gain.

I know this is all theory and inaccurate due to a lot of variables but basically to take ten minutes out of a 17km hill at 7% will need a lot of training. It is something like an 18% fitness gain. Maybe manageable over two or three years of steady effort.

Hope this helps. Given the formula it is easy to set something up in Excel and chart fitness on your favourite hill, graph it etc etc

LeGrimp.
That's a lot of weight!hayaku
Dec 15, 2002 8:15 PM
Thanks for your help guys. I will be able to drop 5kg from last year's weight(80kg), unfortunately 15 is out of the question.

I will have a stiffer bike and lighter wheels. Last year I did the race with only very little training under my belt. I'm hoping for a miracle... but not betting on it.

We'll see what happens, if I'm successful you'll definately hear from me!

Thanks again.
M.
Keep us postedLeGrimper
Dec 16, 2002 2:13 AM
Good luck with it all.

If you were 80kg last year and 75kg this year with a lighter bike, say 7kgs rather than 10kgs,

then for the same power you should be looking at somewhere in the region of 55 - 56 minutes for the 17kms.
Some answersKerry
Dec 15, 2002 6:42 PM
A 150 lb rider would have to lose about 35 lbs. A 180 lb rider would have to lose about 42 lbs. This effort is about 285 watts for a 150 lb rider, 330 for a 180 lb rider.