PhatBobby
There was a nice little table in Runner’s World that illustrates how much faster you could be if you lost weight. Of course, this would not take into account speed increases due to training.
There was a nice little table in Runner’s World that illustrates how much faster you could be if you lost weight. Of course, this would not take into account speed increases due to training.
According to RW author Amby Burfoot, runners on average get 2 seconds per mile faster for every pound they lose.
Does anyone know of a similar table or ‘rule of thumb’ for cycling?
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Wow, sorry I do not have the answer but was going to ask this. I was talking after a ride with some guys they said an older Bicycling Mag. article had covered this subject. I’m not sure if they covered flat riding (seems they would) but I was told it did cover riding hills. I was not able to find this.
I hope someone here has this info as we’re always chiding each other on hills and the losers start talking bike weight, big guts etc as the standard excuses!
Best question on here in a while!
EDIT: Here’s something I just found.
EDIT: Mr g variables are understood. Just trying to isolate weight as best as possible. This interests me cause my weight fluctuates a lot and I do note a difference taking variables into account. Here’s a variable – If I have a gut I find breathing much harder bent over and my form is not nearly as good, harder to keep my knees in etc. So like several have said (me too, just not here) losing body weight is far cheaper and in general better anyway. I feel stupid riding a 15+ lb bike with love handles droping over my shorts!
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I think Amby Burfoot et al. are talking hypothetical tripe.
I wouldn’t take any notice of this pseudo-science!
Any weight loss their guinea pigs made was down to some sort of regime or training, hence the perceived improvement time! Besides that everyone is ‘wired’ differently so its hard to pinpoint.
Sorry, but I wont even attempt a rule of thumb for rider weight loss, and speed gain, I don’t think many others here will do either. . . . but I could be wrong!
If you want to lose weight and enjoy cycling then – Wahey it’s a bonus!
EDIT: I hate to take issue with your link MR but the ‘Assistant professor assumed’ ! ! – I think that says enough! Also please bere in mind that a heavier rider will chomp harder on the pedals whilst out of the saddle, will go faster on downhill sections and be more resilient to strong headwinds,etc. ! ! Do you see what I mean? – Too many variables.
EDIT2: I see where you coming from M R – It would be nice to isolate the one component (personally I dont think it can be done but there is a remote possibility,- that I could be wrong!!)
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It actually depends on the terrain.
On flat land, most of your energy is consumed overcoming wind resistance – so your speed will increase very little (if any). The only increase will be the energy gained from weight you lose related to tire friction (unless you lose tons of weight and significantly reduce your cross-sectional area). This would be such a small amount (assuming it’s only a couple of pounds), it’s pretty much negligible when considering wind resistance increases with the square of velocity.
On hills, you would notice the most gain. Since you have less weight, less wind drag (due to lower speeds), you have to do less work to achieve the same speed. (Work = force x distance). It’s the equivalent of picking up a box that weighs 25 pounds compared to one that weighs 30 pounds. You’ll be able to pick the lighter one up faster. How much faster depends on the difference of the weights.
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I did a rough calculation and it costs about $700 a pound to take weight off my road bike and I save money taking weight off of me. So when I dropped 22 pounds since Jan 1, I figured I saved $15,400 by not having to spend it to lighten my road bike the same amount of weight . Now I have $15,400 that I would’ve spent to lighten my old road bike to spend on a new road bike and that will make me much faster than I was on the old road bike with the 22 pounds I had before Jan 1. Got that?
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First of all, I don’t know the answer. And as per one of the earlier respondents answer, there truly are many variables that cannot be measured.
However, you can potentially calculate a valid answer using basic physics. Assuming a constant power output (thus, no change in fitness level) and same slope, you can calculate speed based on the change in weight.
Been out of school too long to know which formula to use, but conceptually, it could be done!
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The two second rule only works for running because you’re lifting your entire body weight with each stride. All else being equal, lighter is always faster for runners. There’s no similar rule for cycling, and if the road is flat you probably won’t save anything at all. You can make a pretty good estimate for roads steep enough (maybe around 8%) for wind resistance to stop mattering. Increase in speed (m/s) per kilogram of mass lost works out to:
0.102*P*sqrt(1e4+G^2)/(G*m^2)
P is power in Watts, G is % grade, and m is starting mass in kilograms.
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Several of the above posters are correct as it doesn’t apply to cycling with-in reason. Ambry’s 2 sec/lb only is if you are over your “ideal” weight. Keep on loosing weight past your ideal weight and you will run slower.(if you are 6′-6″ tall and 80lbs your nick-name won’t be flash) In cycling it is all about three things, 1) Power output on flat ground) 2) Power to weight ratio when climbing. 3) Technical skills when descending a steep curvy road and mountain biking.
Note: Aerodynamics becomes an important part in limiting your top speed.(your power needs to increase by a factor of 4 as your speed doubles.)