Weight loss = Increased speed
 

I wasn't sure if I should put this here or in Road Cycling but my question is:

Riding the same bike, under the same conditions, how much difference in cruising speed could one expect from a 30-pound weight loss?

I know there is a formula out there somewhere and an online calculator that let you plug in different variables such as incline, wind speed, weight, etc. but I couldn't find it and as I remember I had problems getting it to work correctly back when I first saw it.

Last fall I was cruising (60 minutes or more at steady pace) at about 18mph on flat ground with no wind. 28lb touring/hybrid 700c x 28 Bontrager H2 eco tires. I weighed 230 lbs and have the goal of losing 30 pounds by April 1 (I'm about half way there). I'm not looking for advice on training or on getting a lighter road bike (I already have a project road bike in the workstand). I'm just curious about approximately how the loss of 30 pounds of excess (fat) bodyweight would effect average cruising speed, isolated from other variables.

My plan is better training, better bike, and the loss of 30 pounds of excess weight in preparation for doing a couple of charity centuries and being better on group rides. Just for curiosity's sake, I'm wondering how much of the improvement I'll hopefully see comes from the bike, greater strength and endurance, and how much is because of the loss of excess baggage.

A way to look at it would be if I rode one day with a 30-pound weight vest, took a day of rest, and then rode the same course, on the same bike, under identical weather conditions, but minus the weight vest, how much speed could I expect to gain.

I'm closing in on 30lbs loss now, and I'd guestimate a couple mph increase in cruising speed and much more climbing ability.

However, I have no idea how much is from weight loss, vs improved strength and endurance.

About the closest I could guess to your real question would be when I load my paniers with 30lbs of groceries; this does noticeably impact my off-the-line acceleration, but on the flats once at speed, it doesn't really seem much different. It also, of course, strongly impacts climbing.

Given the same level of fitness it won't make a big difference on the flats but it will be significantly easier to stay with the group on hills. On anything over about a 6% grade you should be a little over 10% faster, e.g. a hill that previously took 10 min to climb should take under 9 min at your new weight.

I am hoping/expecting to see these results from losing weight:
1 - increased tolerance to heat
2 - easier breathing
3 - easier to increase cadence due to lighter legs
4 - faster climbing
5 - easier to find bike clothes that fit
6 - difference in how cold is tolerated
7 - less issues chafing
8 - less hand numbness (less weight on hands)
9 - easier to maintain aero tuck
10 - not needing to eat as much to maintain energy levels (which may make it harder to lose weight)
11 - possible loss of power if you do not make special effort to do strength training
12 - adjustments in how you ride in winds
13 - need to replace bike shorts possibly new style to provide same compression/fit characteristics

Yup, for sure, power to weight ratio goes up(roadies always talking about this) when you lose fat... you'll get up those hills faster!

Congrats on your weight loss and good luck on your continued success. Hard to answer your question: there are way too many variables. Assuming your power output remains the same, you'll go significantly faster up a hill and negligibly faster on the flats. That's because the important metric when climbing is power to weight; on the flats it's power to frontal area.

On level ground, body weight by itself has only a very small effect on speed. There is no gravity to overcome, the energy needed to accellerate to speed is a very small component, and the change in aerodynamics is small (you're still as tall as you were before). It's not 2 mph. It's not even .2 mph.

On a hill, it depends on how steep the hill is. Here's a calculator: http://analyticcycling.com/ForcesLessWeight_Page.html
Pick your favorite climb and plug the numbers in.

What will make you faster everywhere is being in better condition. If you ride more to lose weight, you'll get that in addition to losing weight.
Double win!

http://www.analyticcycling.com. Using all defaults except combined rider bike weights of 258 and 228 gives speeds of 24.45 and 24.65 mph.

Rough rule I follow: 5 pounds loss is .5 minutes savings over a 5km climb.

What caloso said. Keep on biking! You'll see improvement from reduced weight and significantly improved fitness. The only controlled ways I can think of to test the difference NOW (I would not) would be to do your test with and without 30# of stuff on the bike. Or find someplace that has Computrainer indoor trainers and try a climbing course at two different weights entered into the system.

For sure. I went from 195 to 175 over the summer, and I could fly on my bike. I could keep up with the bikers that looked like they were pros, even on my old beater vintage Bianchi, which was my first bike. Now, it's winter and I bulked up a bit again both in muscle/fat, and am sitting around 200. I don't find myself sitting in the top 2 gears as often as I did when I was 25 pounds lighter and riding probably 20-30 miles/day. Of course, I'm sure conditioning has a huge part in performance, too. It's all good though because I'm going to cut the fat, keep the muscle, and hopefully be even faster than before. You do the same, and you'll love the results.

This is very, very true! Especially going up hills.

Me and my dad go for rides sometimes together in the summer, I way 150lbs, and he's about 250lbs, now I know that is a very big difference but when we go up hills, I'll be him up by about 30 seconds to a minute (depending on the size on hill) and on the downhill he beats me by the same amount. In my opinion, weight plays a big roll in speed.

Weight means nothing on the flat, I am 192lbs and my Dad is 260lbs or more - he can beat me on the flat because he is slightly stronger. Not much stronger, but just a bit stronger and that makes him faster. As soon as we get near a hill it is see-ya-later time as I sit back and relax at the top of the hill waiting.

I've lost about 61 pound since this time last year. My normal cruising speed has picked up from about 12mph to 14-15mph. Average speed over the whole ride has increased as well, but not as much. There's a steep hill close to the end of my usual route that I like to challenge myself with. When I was first able to tackle it last year, I got up at about 3-4 mph. The other day I did it at 5-6mph, and wasn't breathing or struggling nearly as much as I used to. I'm figuring the improvements are due in part to being stronger and partially to towing around less weight.

I'm not sure it's possible to figure a speed gain due to weight loss. If you were talking about the speed difference of having 30lb of fat surgically removed from your body (assuming you could do it with no complications and ride the day before and the day after the surgery) then you'd probably notice you were faster up hills but possibly slower down hills.

If you're talking about weight loss achieved as a result of cycling you'll have all sorts of other variables in there as well. When I started cycling my weight stayed much the same but I got thinner - for all I was losing fat I was gaining muscle and getting fitter. Then when my weight started to drop the muscle and fitness continued to ride, which makes it impossible to figure how much of my performance gains were due to having less fat to haul and what was due to being stronger and fitter.

One of us is unclear on what that word means.

... which is all well and good, if you can change your weight while keeping everything else constant.

If you can show me someone who lost 30 pounds without changing their strength, fitness, effective frontal area etc then your link is useful. Otherwise, read the context of the part you selectively quoted.

Read the OP.

Asgelle - great work taking my post out of context, make you feel good?

I said on the flat. If you have the same power to weight ratio or whatever then being heavier means nothing. I explained this in my post.

I suppose one could ride a given route on a bike, then load up some panniers with the amount of lost weight and see what the difference is. That would give an approximation of how much is due the weight and how much to gained strength.

First, you stated it, but never explained your reasoning. Second, you're wrong. 2/10 mph might be small, it might be insignificant, it might be negligible, but in no way is it nothing.

I lost 30lbs and didn't get a bit faster on flats... But I did gain endurance, better comfort, and slightly better climbing ability. Since I didn't ride much while losing the weight my guess is those benefits weren't from riding but from weight loss.

In my experience I find weight has a huge affect, you can take all those charts and through them away. To many variables to consider and the mind also has a lot to play in it. I find a big difference whenever the scale goes up or down 10lbs, those charts do not equat fitness results of less body mass. I can push a higher speed longer on flat ground at 195lbs then I can at 205lbs and above, don't care what a chart says it's what I experienced and climbing difference was huge. I've rode anywhere from 305lbs to 197lbs but most has been done around the 220lb mark. The difference for myself between 220 and 200 are drastic, last year I let myself go again and I could not perform at the level I know I can which I will not let happen again, I'm on a journey to get under 180lbs by August and I can't wait to see how I can ride under 190 let alone 180! Like I said forget about the charts....make your own!!!

On flat ground, the weight alone won't make much difference. I think the formulas you're thinking of are for climbing. There will be increases in speed due to overall health, but that would be hard to quantify and put into a formula.