How much effect does losing weight have on speed?

Craig0657

Hey Guys,

After watching a few GCN videos about this I've been inspired to drop a bit of weight to see if this improves my speed on climbs (and gets me some more strava trophies ) Just wondering how much faster I could expect to be if I dropped 5kg? Is there any scientific formula or graphs on this or is it all guesswork?

I'm 26, 6ft and currently 85kg, I have a decent fitness level and am currently riding around 40miles 3 times a week, averaging between 15-17mph depending on how hilly I chose the route. I'm also doing around 5 hours of gym based exercise a week aswell as the riding.

milemuncher1

Craig0657 wrote:

Hey Guys,

After watching a few GCN videos about this I've been inspired to drop a bit of weight to see if this improves my speed on climbs (and gets me some more strava trophies ) Just wondering how much faster I could expect to be if I dropped 5kg? Is there any scientific formula or graphs on this or is it all guesswork?

I'm 26, 6ft and currently 85kg, I have a decent fitness level and am currently riding around 40miles 3 times a week, averaging between 15-17mph depending on how hilly I chose the route. I'm also doing around 5 hours of gym based exercise a week aswell as the riding.

In my experience, a 'trimming' ( losing a couple of Kg's) is not as effective as increasing your power, thus increasing your power to weight ratio, by increasing power, rather than losing weight (unless it's a lot of weight). If you want to be better at hills, you need to increase your muscle endurance, rather than just the muscle power. I found a good way to do this, is just to attack hills in as big a ratio as you can, for as long as you can manage, and resist the urge to downshift and 'spin' until you physically can't go any further without doing so. If you want to augment this in a gym, get to a leg press machine, put as big a weight as you can shift, onto it, then work on seeing how quickly you can lift the weight, and how many times you can lift it. It flies in the face of the accepted best practice / technique ( to an extent) but it's effective, you just have to be very careful not to lock your legs straight by accident.

Pross

It will make quite a difference going uphill but little difference on the flat (other than most people's general fitness improves as they lose weight, assuming it's mainly fat).

I wouldn't bother with he leg press idea above, specificity is the way to improve muscular efficiency / power in any sport. Fit in some higher intensity rides on the flat and hill repeats among your normal riding. There's plenty on the training section here from people far more knowledgable on the subject than me so take a look on there.

fenix

Ditch the gym and cycle more.

pblakeney

Craig0657 wrote:

... I'm also doing around 5 hours of gym based exercise a week aswell as the riding.

You could do 5 hours extra cycling instead.

Craig0657

Thanks for your replies guys, it was just 1 particular GCN video that mentioned "if an 80kg rider lost just 5kg they could improve their time on a course by upto 4 minutes" that got me wondering if there was an exact formula for this.

As for ditching the gym work, I'm actually a PT and the 5 hours are a combination of spin classes and Body Pump that is 150-200 reps of pretty much every exercise you can think of.

yiannism

Its way more efficient to lose body weight than spend 1000 just to have 1kg lighter bike. I cant give you numbers but i can tell you that after ive lost 7-8 kg (i am 180/87kg now) my climbing ability got huge improvement.

Craig0657

YiannisM wrote:

Its way more efficient to lose body weight than spend 1000 just to have 1kg lighter bike. I cant give you numbers but i can tell you that after ive lost 7-8 kg (i am 180/87kg now) my climbing ability got huge improvement.

Glad to hear it! I've dropped 5kg in the last month just through riding more and have noticed a lot more pbs on segments so if I can clean my diet up a bit another 4-5kg should drop off pretty easily in the next few months.

fat daddy

the best of the GCN videos is ther one where they ride up a 5k hill with a power meter, one doing 230w and one doing 275w with a 5kg ruck sack on.

then resting, rehydrating and doing the same again but without the rucksack on.

so same power, same hill, same conditions but 5kg difference over 5k worked out about 1minute difference or something ??

imposter2.0

Fenix wrote:

Ditch the gym and cycle more.

^^ this. If you want to improve on hills, then w/kg and sustainable power are all that matter.

svetty

At 6ft and a PT you likely have lean muscle mass rather than fat. Depending on your build I'd not strive to be much under 75kgs TBH. Sustainable power is the key here

timothyw

There's a calculator here:
http://www.cyclingpowerlab.com/PowerSpeedScenarios.aspx

Plugging a few sample numbers in, losing 5kg means you will go about 1kph faster up a 5% incline for the same effort.

milemuncher1

Fenix wrote:

Ditch the gym and cycle more.

Pretty much this ^

milemuncher1

YiannisM wrote:

Its way more efficient to lose body weight than spend 1000 just to have 1kg lighter bike. I cant give you numbers but i can tell you that after ive lost 7-8 kg (i am 180/87kg now) my climbing ability got huge improvement.

This is very true. I know people who are retentive beyond belief, about saving a few grammes here and there, and spending big bucks doing so, but neglect their great big beer belly. It isn't rocket science.

Pross

Yeah, it can be calculated but would be very long winded to do with any accuracy over an actual course. You'd need before and after power figures, frontal areas and anything impacting on resistance. The basics of how much difference it makes on a set gradient all other things being equal are fairly simple physics that I assume are fed into the calculator linked above.

kajjal

Its a trade off, loose too much weight and your strength and fitness suffer. Loose unneeded weight and it helps alot especially up hills. In the summer due to being alot fitter i weight about a stone lighter and really notice the difference compared to winter.

StillGoing

Craig0657 wrote:

Hey Guys,

After watching a few GCN videos about this I've been inspired to drop a bit of weight to see if this improves my speed on climbs (and gets me some more strava trophies ) Just wondering how much faster I could expect to be if I dropped 5kg? Is there any scientific formula or graphs on this or is it all guesswork?

Tons of difference. I'm about 6kg over my weight from last season and on hills it makes a noticeable difference. Even 3.5kg makes a difference on a decent gradient.

ZMC888

Mathematically speaking dropping 5kg will save you time in the hills, but in my experience as someone that is 6ft, and has been 120kg and now weighs 79kg other factors are just as important.

In my opinion these other factors such as tires, drivetrain condition weather, air temperature, your fitness, nutrition and how you are feeling on that particular day all have as much effect. Even the right music can give you a big boost.

Also fair chunk is down to the bike, riding a light bike that inspires confidence that fits you well gives a big boost.

DavidJB

Waiting for OKGO to come and say it's fine being a fatty

Craig0657

Thanks for all the replies guys, here's to a lighter and faster summer of riding!

haydenm

YiannisM wrote:

Its way more efficient to lose body weight than spend 1000 just to have 1kg lighter bike. I cant give you numbers but i can tell you that after ive lost 7-8 kg (i am 180/87kg now) my climbing ability got huge improvement.

Is it? Surely it's entirely dependent on how much money you have? Losing 1kg is a pretty good saving, it takes me a lot less time to blow £1000 than it does to lose 1kg, seems quite efficient to me...

I lost ~2kg of bike weight between my steel tourer/cx and my supersix, it's made a noticable difference on climbs. Coming into good weather I will be aiming to lose a further 2kg to 4kg (unlikely) of body weight so I'm hoping to see similar improvements, it's way less effiecient than just getting on a different bike though

DavidJB

Weight on the bike is dead weight...weight on the rider at least gives you more power.

fat daddy

DavidJB wrote:

Weight on the bike is dead weight...weight on the rider at least gives you more power.

I knew all these extra inches around my waist were powering me along ...... think at lunch I might increase my wattage by going to McD's and growing my racing gut

homers_double

*points wife in direction of this thread*

haydenm

It's doubly inefficient for me to lose 2kg over buying a new bike as the weight is from being a borderline alcoholic, cutting out the beer would mean being unpleasantly sober for extended periods of time and that is a sacrifice I am just not willing to take.

Sorry for lowering the tone. As an aside, am I kidding myself that because I'm short and weigh 63kg it's less of a priority to lose the excess belly fat as I'll be lighter than most anyway? I'm fitter than I ever have been despite the seemingly immortal 16.8% body fat...

okgo

DavidJB wrote:

Waiting for OKGO to come and say it's fine being a fatty

I've lost a fair bit since last year to be fair, about 77-78kg vs 82 - noticed marginal difference in the time trials I've been doing over hillier courses, time will tell when I do some harder road races I guess but at this point it isn't night and day, though I can now get into a medium Nopinz skinsuit so that probably has helped also.

On the flat the weight makes almost no odds once you're up to speed, but if you can retain power and be leaner then I can't see an issue with that and I don't think extra weight = extra power. I still seem to have the same power as before, so that's handy. I've used the callipers a few times over the last few weeks and am about 6% bodyfat, which I suppose is about the sort of level you could sustain without getting sick too often.

timothyw

HaydenM wrote:

As an aside, am I kidding myself that because I'm short and weigh 63kg it's less of a priority to lose the excess belly fat as I'll be lighter than most anyway? I'm fitter than I ever have been despite the seemingly immortal 16.8% body fat...

Ultimately it depends on if you want to go faster on the flat or faster uphill.

If you want to go faster on the flat you are better trying to build up your sustainable power, in the process of doing that you might lose a bit of fat, but will probably compensate with a bit more muscle.

If you want to go faster uphill, then yeah, shifting the excess fat is the best way to do it.

If you want to go faster downhill, I'll meet you at the pie shop.

Personally I'm at the other end of the scale - at 120kg, even if I lose a couple of stone I'm still not going to be able to climb with the mountain goats, so I just don't worry about it.

fenix

OK if you're 120Kg - then your climbing will suffer - but would it be possible to lose weight for your general health ? (dunno you may be 100% muscle).

Its easy to overlook the bigger picture when we are talking of cycling.

Being a healthy weight will help you have a longer healthier life ? More time for cycling - hurrah !

haydenm

TimothyW wrote:

HaydenM wrote:

As an aside, am I kidding myself that because I'm short and weigh 63kg it's less of a priority to lose the excess belly fat as I'll be lighter than most anyway? I'm fitter than I ever have been despite the seemingly immortal 16.8% body fat...

Ultimately it depends on if you want to go faster on the flat or faster uphill.

If you want to go faster on the flat you are better trying to build up your sustainable power, in the process of doing that you might lose a bit of fat, but will probably compensate with a bit more muscle.

If you want to go faster uphill, then yeah, shifting the excess fat is the best way to do it.

If you want to go faster downhill, I'll meet you at the pie shop.

Personally I'm at the other end of the scale - at 120kg, even if I lose a couple of stone I'm still not going to be able to climb with the mountain goats, so I just don't worry about it.

I do want to go faster uphill but then when compared to the guys I ride with I already have at least a 10kg weight advantage. I see the weight loss as a bi product of spending time riding up hills to get 'fitter' rather than the end goal?

I like going fast downhill but I tend to do that specifically on an MTB and the fitter/stronger I am the faster I go, so no excuse for pies :oops:

slowbike

If you just want to go faster downhills then fit another couple of bottle cages and fill up at the top.

Practically everyone I know could benefit from losing a few pounds (of fat) - including myself - that stored fat isn't making me go faster or increase my staminer - it's just stored energy that isn't going to be used during a (normal) ride - a bit like carrying those emergency gels/bars or even money - you don't need it (most of the time) - difference is that those gels/bars and money (unless you're carrying coppers!) weigh a lot less ...

timothyw

Fenix wrote:

OK if you're 120Kg - then your climbing will suffer - but would it be possible to lose weight for your general health ? (dunno you may be 100% muscle).

Its easy to overlook the bigger picture when we are talking of cycling.

Being a healthy weight will help you have a longer healthier life ? More time for cycling - hurrah !

I could safely lose a good bit of weight but ultimately I'm 6ft4, short legged and built like a brick shithouse so it's hard (plus I have a two year old at home so there isn't a lot of time to carefully plan meals)

I don't have any concerns about my health, I knock out 140 commuter miles each week and can just about hold my own in Cat 4 crits (although have a bit of work to do there!)

If you met me, you'd be surprised that I'm as heavy as I am - most people are anyway!