Do some bikes roll faster?

[summerdays]

<Daft question alert>
I've noticed when I cycled with two different friends that when going downhill freewheeling, if I am behind them I keep catching them up, or if infront I end up ahead of them.

Does my bike roll faster, or is it that I'm perhaps slightly heavier (less than a stone I would guess - I'm 10st 9 ish). Or could it be just that they hit the brakes quicker. All bikes are under £500 although one of them is a new Trek about £500, both of their tyres are probably skinner than my Marathon ones.
</Daft question alert>

 

[Aint Skeered]

The weight of the rider comes into being.
I certainly descend faster than my 'less fleshed' teammates.
I am pretty sure the bike set up also has a lot to do with it

 

[piedwagtail91]

in our clubs frewheel contest, i've used the same bike but with different wheels. i changed from a shimano setup with xt hubs to campag with some record hubs.the bike went further on the campag.in similar conditions. ie wind direction and strength.tyyres were the same on both occaisions.
it may be down to the heavy duty seals on the xt. comparing to other riders then i'm about 15 stone and usually drop the others even on fixed.
i think that body weight, bike positon and possibly hubs/bearings all play a part.

 

[LordoftheTeapot]

Gravity has a part in it as well (I should of been a scientest)

 

[stevenb]

It's your weight (you & the bike).....thats all there is to it.

 

[Smokin Joe]

Tyres.

 

[Keith Oates]

It's a combination of several things, weight, tyres, wheel bearings and aero position are the main ones I can think of for now!!!!!!!!!!!!!!!!!!!

 

[Crackle]

What they all said.

Two riders of unequal weight on equalish bikes - heavier rider will descend faster.
Two riders of equal weight on equalish bikes - the one in the best aero position will descend faster.
Two riders of equal weight in the same aero position - the bike with the least rolling resistance will descend faster.

Least rolling resistance will probably be tyres first, hubs and stuff second.

 

[Fab Foodie]

Your wheels and tyres make a massive difference.

Put the skinniest, lightest tyres you can get away with on and you'll notice a marked difference immediately.

I've noticed this since I've had 2 sets of wheels. The lighter aero Reynolds Alta-Race with Michelin PR2's seems to out-roll anybody that I regularly ride with but when I swap to my heavier non-aero CXP22's on Ultegra with Krylions I seem to roll at the same aspeed aseverybody else. The Reynolds/PR2's combo is noticeably faster downhill.

 

[Cycling Naturalist]

What they all said.

Two riders of unequal weight on equalish bikes - heavier rider will descend faster.
Two riders of equal weight on equalish bikes - the one in the best aero position will descend faster.
Two riders of equal weight in the same aero position - the bike with the least rolling resistance will descend faster.

Least rolling resistance will probably be tyres first, hubs and stuff second.

To analyse it down a bit further:

The heavier bike and rider will have the greatest potential energy to enable them to go faster and further. However, the energy has to be used efficiently for this to happen.

 

[Dave5N]

Bloody hell. Haven't you lot ever heard of Galileo?

 

[piedwagtail91]

Bloody hell. Haven't you lot ever heard of Galileo?

the European satellite gps system?

 

[Dave5N]

Funny, but more amusing is the pompous way certain people spout nonsense as if it is established fact, when a cursory glance at a GCSE physics book would put them straight.

 

[Crackle]

Funny, but more amusing is the pompous way certain people spout nonsense as if it is established fact, when a cursory glance at a GCSE physics book would put them straight.

What, so if you drop two riders from a tall tower, the heavier one won't reach the ground first?

Did Galileo do Potential and Kinetic energy as well then?

 

[Dave5N]

No. The weight ( or properly, the mass) doesn't affect the acceleration. Ignoring friction, they will fall at the same rate.