Page 1 of 11

Weight

Posted: 25 Jun 2014, 3:34pm
by al_yrpal
Reading a few threads about new road bikes on here I had almost convinced myself I need to get one. I feared that what I have been riding is too slow because its too heavy. So, I decided to weigh my bike, a 1971 Mercian Professional fitted with a Campag Veloce groupset and a Brooks Professional saddle, it weighs 10.6 kg. To my surprise this is the same as many of the latest road bikes although you can get 7kg+ road bikes but they are silly money.

I then weighed what I usually carry, pump, spare tube, seat pack, wallet, phone, keys lock and water, this added up to 1.9 kg.

Having lost 33 lb of flab recently I am aware that this has made hills much easier. I can usually average about 12.2 mph on a ride around here which involves both moderate and steep hills, making little effort. If I do try to put in some effort I can push my average up to 13.5 mph.

This has left me with a few questions:

Would 3 kg less make any difference?
Am I carrying too much stuff?
Is my old bike inherently slower than modern bikes for some obscure reason and if so what is it?

Al

Re: Weight

Posted: 25 Jun 2014, 3:48pm
by Mick F
This is a good question, and one I have been contemplating raising myself.

All-up weight is the weight your body has to cycle along with.
Acceleration and climbing hills are a problem, but steady flat riding makes no difference. Down hills you're better off heavier.

As for carrying stuff, I take two CO2 cylinders and an adaptor, a set of plastic tyre levers, two inner tubes, and a small multitool ...... all stuffed into a small bag behind the saddle. Water bottles? I take some if I need to, either one bottle or two. I only fit mudguards when I need to. Basically, my 531c bike is as light as it's going to be. I've lost nearly a stone over recent years, and I'm as light as I'm going to be.

Bike 23lbs, me 12st = 191lbs = 86.64kg all-up weight.
If I had an 18lb bike, my all-up weight would be reduced to 186lbs = 84.37kg

Make a difference ............ I don't think so! :lol:

Re: Weight

Posted: 25 Jun 2014, 3:54pm
by Freddie
They say extra rotating weight makes the most impact. I don't know if ultra light inner tubes, lighter tyres and wheels would be feasible and worth trying, or even how much difference they would make to your riding? Your brooks weighs a lot compared to other saddles, but I doubt you're eager to part with it.

I tend to like certain components, so it doesn't leave me much in the way of options for losing extra weight from my bikes.

Re: Weight

Posted: 25 Jun 2014, 3:58pm
by AndyBSG
Just out of interest, how did you weigh the bike? I'd like to weigh mine but don't think my bathroom scales are right for the job :)

Re: Weight

Posted: 25 Jun 2014, 4:08pm
by tatanab
Me- age 62, 73kg
Daily ride including saddlebag with cape, tools etc - 17.7kg
Average speed with steep and/or rolling hills (not on the scale of Mick F) - 14 to 15 mph.

Last week I took out another machine which weighed 9.5 kg with a pared down bag and contents totalling 10.5kg. Riding at the same perceived effort (small) I averaged 15.5 mph so possibly as much as a massive 1mph difference when shedding 7kg. Does it matter?

Re: Weight

Posted: 25 Jun 2014, 4:08pm
by Mick F
Bathroom scales aren't absolutely accurate of course, but the difference between two readings will be much better than the absolute figure.

Weigh yourself whilst holding your bike and record the weight.
Weigh yourself only, and subtract it from you+bike.
You can do the same with your child/dog/cat/rabbit. :D

We bought a luggage weighing thingy from Lidl's a few months ago. Basically a spring balance, but digital. It has a strap and hook arrangement that you can hold your suitcase, and as you lift it off the ground the scales record the weight - in lbs or kg.
I did it with my bike held by middle of the top tube, and got the same figure as per the bathroom scales method above.

Re: Weight

Posted: 25 Jun 2014, 4:09pm
by hondated
AndyBSG wrote:Just out of interest, how did you weigh the bike? I'd like to weigh mine but don't think my bathroom scales are right for the job :)

Andy I think that you could use your scales and just stand on them holding your bike.

Re: Weight

Posted: 25 Jun 2014, 5:02pm
by al_yrpal
If you step onto my scales the digital displays zero. Then you simply pick up the bike and the weight is displayed. To weigh yourself you dab the scales with your foot, they zero, then you step on.

Perhaps I should loose more weight, cheaper than another bike!

Al

Re: Weight

Posted: 25 Jun 2014, 5:52pm
by mjr
I'm sure there was a report from a doctor commuting who bought a light tart bike, randomly selected whether to ride that or his previous heavier one each day and found it was like 30 seconds over 15 miles or something of that order - basically, not significant and random chance at traffic lights could make more difference. I can't find it, but I did find this lovely quote from the often-great Dave McCraw:
http://mccraw.co.uk/bike-weight-performance/ wrote:When somebody jumps on a lighter bike and claims to have taken minutes off their local climb they’re either benefiting from placebo or they live at the foot of Mont Ventoux!

I'm meaning to weigh my bikes soon. I think the manufacturers claim they weigh 15kg and 17kg. My current grab-bag of tube, tools, waterproof, snacks and stuff is 1.5kg (just weighed it) and the locks are about the same again. There is stuff that I've omitted from the grab bag when riding with a local fast group (sun block and puncture canister, for example) but usually I prefer the convenience to the minor speed benefit.

Anyway, it's the fens. The wind dictates my speed most of the time. :lol:

Re: Weight

Posted: 25 Jun 2014, 7:24pm
by reohn2
I don't own a solo bike that weighs less than 13kg.
I've long since forgotten to worry about weight or speed.
I ride at the effort I feel comfortable with,that would make a difference when climbing or accelerating on a lighter bike,flat and mildly undulating terrain there wouldn't be much difference.
Some folk like a light bike to make climbing easier,TBH if I climb two or three gears lower them it doesn't worry me at all,if I had to struggle to keep up with a group due to bike weight I'd wave them off.
The two Vaya's and Kona Dew Drop suit me fine,comfortable(in the case of the Vaya's extreeemely comfortable)handle well and will go any where I point them and point them down some unusual ''roads''.
I've no need for fancy pants lightweights to raise my average speed,it means nothing to me :)

Re: Weight

Posted: 25 Jun 2014, 8:27pm
by Brucey
al_yrpal wrote:
This has left me with a few questions:

Would 3 kg less make any difference?
Am I carrying too much stuff?
Is my old bike inherently slower than modern bikes for some obscure reason and if so what is it?

Al


respectively;

-yes, but not that much
-probably.
- yes; it might have slow tyres but it won't be very aero, and you might not be very aero when you are sat on it.

However overall, there are not huge gains to be made through lightness, low Crr tyres, and (within reason) aerodynamic bikes/riding positions. If you want to go faster you can get a small benefit from these things (about 0.5- 1mph each) but I'd suggest that there is probably a much larger chunk of extra speed to come from the 'engine'.

Somwhere online there is a calculator which works out power vs speed for different bikes/riders and you can play around with some of the variables and see how you get on.

cheers

Re: Weight

Posted: 25 Jun 2014, 8:37pm
by Mick F
Brucey wrote:........ but I'd suggest that there is probably a much larger chunk of extra speed to come from the 'engine'.
I'd suggest that it's definitely the major chunk of speed that comes from the engine.

Re: Weight

Posted: 25 Jun 2014, 8:40pm
by recordacefromnew
Freddie wrote:They say extra rotating weight makes the most impact.


Double at the tyre/tube/rim, varying to no difference compared to any non-rotating mass on the bike at the hub, and only in terms of effort to accelerate.

Re: Weight

Posted: 25 Jun 2014, 9:25pm
by jb
The total weight on its own isn't necessarily the problem. An extremely light bike can be thrown about under the rider when honking up hills in a way that would be noticeably more tiring on a heavy bike.

Re: Weight

Posted: 25 Jun 2014, 9:45pm
by easyroller
Of course you need a new bike! :D




/end