Weight

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Mick F
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Re: Weight

Postby Mick F » 26 Jun 2014, 9:03pm

Brucey wrote:...... a 1% weight reduction might make for almost 1% increase in speed.

Almost?

1% ....

I weigh 75kg plus a bike of 10.5kg making an all-up weight of 85.5kg
I cycle at 7mph up the hill from the river into Devon for 1.5miles (2,650yds) and take 13mins

Say I swapped my bike for a light CF 7.5kg, my all-up weight would be 82.5kg - ie minus 2.5%

Therefore I'd climb into Devon 2.5% faster - ie 7.175mph.
This means I'd save ..... what? 5 seconds? 4 yards? .............. maximum?

What's the point unless I'm Wiggo?
Mick F. Cornwall

Brucey
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Re: Weight

Postby Brucey » 26 Jun 2014, 9:19pm

your maths may be flawed ( you would be nearly 20s faster up a 13 minute climb by my reckoning) but I don't disagree with the conclusion.

And a few less pies is a lot cheaper and simpler if you want to lose that little bit of weight... :wink:

cheers
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Mick F
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Re: Weight

Postby Mick F » 26 Jun 2014, 9:34pm

Sorry, arithmetic may be flawed at this time of the evening. :lol:
Glad you get the picture though.
Mick F. Cornwall

OnYourRight
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Re: Weight

Postby OnYourRight » 26 Jun 2014, 9:45pm

I make it about 27 seconds. If we get a few more takers I reckon we can save Mick F a minute!

Brucey
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Re: Weight

Postby Brucey » 26 Jun 2014, 9:52pm

OnYourRight wrote:I make it about 27 seconds. If we get a few more takers I reckon we can save Mick F a minute!


I agree, because a 3kg saving is ~3.6% not 2.5% overall.

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cycleruk
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Re: Weight

Postby cycleruk » 26 Jun 2014, 10:25pm

3kgs = 3 bags of sugar.
Put the 3 bags in your saddlebag and go and do a long climb.
Now take them out, repeat the climb and see how much quicker you are. :mrgreen:
(have a bit of rest between the climbs though. :oops: )
You'll never know if you don't try it.

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al_yrpal
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Re: Weight

Postby al_yrpal » 26 Jun 2014, 10:32pm

I can see where this is leading…. Time to break out that concrete block again Mick!

:D :D :shock:

Al
Touring on a bicycle is a great way to explore and appreciate the countryside and towns you pass through. Make a difference...

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Mick F
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Re: Weight

Postby Mick F » 27 Jun 2014, 8:42am

Only last month, I rode 800odd miles towing my trailer. The all-up weight of which was about 50lbs.
It didn't slow me down at all .......... except for climbing hills of course and acceleration from a standstill.
Speak to Ferrit Worrier for instance. I rode with him up Cat and Fiddle over to Buxton. He left me standing on the hills, but I was with him all the way otherwise.

Once rolling along, my average speed was near enough the same as it would have been without it. I'm not a naturally fast rider and usually take my time climbing hills, my average speed isn't much affected. Obviously I could race along lightweight, and be held back considerably by weight.

I doubt if I rode a 7Kg CF bike I'd be any faster than on my 10Kg steel steed.

The thing is, I'm a tractor, not a Ferrari. :D
Mick F. Cornwall

Brucey
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Re: Weight

Postby Brucey » 27 Jun 2014, 9:48am

IIRC tractors just use more fuel to go the same speed as usual when the going is tough, which is another side of the same coin.

BTW if you truly have a tractor-like torque curve, you may not need all those gears.... :wink:

cheers
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SleepyJoe
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Re: Weight

Postby SleepyJoe » 27 Jun 2014, 11:17am

Back in October I treated myself to a new Trek Madone full carbon bike
It is about half the weight of my normal commuting bike, an old Dawes Audax with rack & panniers.
The last few weeks I have been commuting on the new Trek and enjoying the ride.
It certainly feels quicker up the hills but doesn't feel so fast down hill or as easy rolling as the Dawes.

Yesterday, I rode my old Dawes for a change (I didn't want to get my new bike wet!)
I went the scenic way home, a 16 mile loop up & down some steep Devon Hills, an hour-ish long ride.
However, I was still 1 minute quicker compared to my best time on my light weight Trek
So much for bike weight making any difference to real world cycling times!

Mark

profpointy
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Re: Weight

Postby profpointy » 27 Jun 2014, 12:12pm

Whilst a few ounces ain't gonna matter, I can certainly tell the difference if I carry my PC home rather than leave it in the office. I guess it's a kg or two. And whilst I've only done a little cycle touring, again you don't really want to care extra because you're loaded already. Certainly if hillwalking with a rucksack, an extra kg very much matters - saying it's "only a litre of water" - is fine and dandy, but when walking in hot climes, how much water you can carry really matters - and every extra litre is a burden

OnYourRight
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Re: Weight

Postby OnYourRight » 27 Jun 2014, 12:44pm

profpointy wrote:Whilst a few ounces ain't gonna matter, I can certainly tell the difference if I carry my PC home rather than leave it in the office. I guess it's a kg or two.

Unless it’s a MacBook Air or something similar, it might be closer to 3 or 4 kg by the time you’ve added its bag, power adaptor, and any other clutter in the bag. Do you have any convenient way to weigh it?

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al_yrpal
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Re: Weight

Postby al_yrpal » 27 Jun 2014, 4:53pm

Reading up on Campag hubs and freewheels “notoriously noisy freewheels" is the general comment on Campag so I am now relaxed about the loud clicking. The DT Swiss freewheel on my Cannondale Rush also makes loud klicking thus indicating to all and sundry you are riding a quality bike I suppose? :lol:

Al
Touring on a bicycle is a great way to explore and appreciate the countryside and towns you pass through. Make a difference...

profpointy
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Re: Weight

Postby profpointy » 27 Jun 2014, 5:51pm

OnYourRight wrote:
profpointy wrote:Whilst a few ounces ain't gonna matter, I can certainly tell the difference if I carry my PC home rather than leave it in the office. I guess it's a kg or two.

Unless it’s a MacBook Air or something similar, it might be closer to 3 or 4 kg by the time you’ve added its bag, power adaptor, and any other clutter in the bag. Do you have any convenient way to weigh it?


. Look up a manufacturer's website if you're that bothered.

Brucey
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Re: Weight

Postby Brucey » 27 Jun 2014, 6:11pm

SleepyJoe wrote:Back in October I treated myself to a new Trek Madone full carbon bike
It is about half the weight of my normal commuting bike, an old Dawes Audax with rack & panniers.
The last few weeks I have been commuting on the new Trek and enjoying the ride.
It certainly feels quicker up the hills but doesn't feel so fast down hill or as easy rolling as the Dawes.

Yesterday, I rode my old Dawes for a change (I didn't want to get my new bike wet!)
I went the scenic way home, a 16 mile loop up & down some steep Devon Hills, an hour-ish long ride.
However, I was still 1 minute quicker compared to my best time on my light weight Trek
So much for bike weight making any difference to real world cycling times!

Mark


if you have good tyres on the dawes but crummy ones on the trek that could easily do it.

Suppose you climb at 200W; a 10% weight saving only nets you the benefit of an extra 20W or so, and that is only when you are going uphill. However, bad tyres (or simply unsuitable ones) could easily 'cost you' 20W (or more) all the time

Also don't forget that your pedalling stroke will have become habituated to the dawes; the slightest change in crank length or riding position may mean that you simply don't pedal so well on the trek.

cheers
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