Time Saved From Weight Loss on Bike

trek madone 6.9

Trek Madone 6.9

A look at how much time and effort we can save by losing weight from either ourselves or our bike. We all know that saving weight helps us to get up hills, but how much will we save, if we can shave off 1Kg from our bike (or lose 10KG off our tummy) ?

As a rough rule of thumb, I had the idea that for  a 100 meters ascent, saving 1Kg would give you an extra 2 seconds.

Analytic cycling have this program to calculate approx time saved from losing weight.

I put in figures for next years Rake hill climb

  • 900 metres.
  • Height gain 100 metres
  • Average Gradient 11%
  • Weight of rider 61Kg
  • power 500 watts
  • Time Saved – 1.7 seconds

This seems about right from my own unscientific tests with different weights on the bike.

By, the way, in 2005 on the Rake, Ben Greenwood beat Jim Henderson by 0.3 seconds. In other words the winning margin was 0.3 seconds or 170 grams.

What About a Climb like Alpe d’Huez?

photo Maurice Koop

  • 14 km distance
  • average gradient of 8.1% (max gradient 10.6%)
  • Height gain 1071 metres
  • power 400 watts
  • 1Kg saved = 24.16 seconds

Lose 10 Kg and you will be able to climb Alpe d’Huez 4 minutes quicker. No wonder, heavier built riders like Mark Cavendish can never compete in the mountains.

Empirical Tests on Alpe D’Huez

According to this site (Alpe d’Huez weight). A rider tired climbing Alpe d’Huez at constant power of 275 watts. With 1.8 extra Kg. It took an extra 66 seconds – which is very close to what the model suggests for 1.8Kg (64 seconds) .

Losing Weight on the Wheel

It is argued that saving weight on your wheel gives an even bigger advantage. This is because a wheel rotates at twice the speed of your bike. Therefore, extra power is needed in accelerating wheel weight. According to the empirical tests on Alpe d’Huez adding an extra 1.8Kg to wheels was an extra 1 minute slower than putting the weight on the bike. Therefore, if you can some lighter wheels, the benefit from the weight saved will be greater.

Test Results from Alpe d’Huez

  1.  52.01, 275w – Normal bike + 1.8Kg extra water in tyres(!)
  2.  51.34, 277w – Normal bike + 1,8Kg extra water on bike.
  3.  49.40, 278w  – Normal bike
  4. 50.38, 273w – Normal bike, reduced tyre pressure only 3 bars.

Other issues in Weight Saving

Power. When climbing it is not all about weight, but also power transfer. If you lose weight at the expense of rigidity and strength, the gains may be lose. When I switched from Aluminium frame to Trek Madone 6.9 Carbon fibre, I felt a stiffer more powerful bike – the weight was actually the same.

Aerodynamics. At certain speeds benefits from reducing aero drag outweigh weight savings. Thus a slightly heavier time trial bike may be faster than a road bike on a hill climb of 3%. (as some found out at National Hill Climb Championships)

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5 Responses to Time Saved From Weight Loss on Bike

  1. Lewis March 27, 2012 at 11:23 pm #

    Wow! I’m carrying a bit of timber at the moment (15 stone) and I not cycling very much. I keep meaning to get my rear in gear and lose the weight (I’m looking at a stone or two) and this sounds like a pretty good incentive!

  2. steve November 6, 2011 at 12:18 pm #

    Great link, and hi to James, who I seem to be the BEFORE version of (120kg). I set myself a mile – 1608m – and a 0.05 slope which I’m hoping is 1 in 20, and about the max gradient I could hope to continue for a whole mile. It’s fascinating what happens as the power drops. A 4kg loss at 500W (lol!!!) gains only 5secs, but at 50W is well over a minute, tho the prog doesn’t say whether that little power would actually make it up the hill.

    Why 4kg? Because I reckon thats about the weight I would lose in sweat getting up the hill :)

    • tejvan November 6, 2011 at 5:22 pm #

      :) Steve, hope one day you will be flying up hills too.

  3. James November 6, 2011 at 8:33 am #

    It’s easier to look at the bike instead of lowering mass of your body.

    I’ve climbed hills at 78kg with ease and waited for friends to catch up but then
    I remember climbing the same hill at 120kg when I was obese and nearly died.

    On the same bike the only change I made was lose the lard, train and enjoy it.

    Nice link too -Gained 338 seconds lol

    • tejvan November 6, 2011 at 5:22 pm #

      wow, that’s quite a big weight loss – impressive

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