What (readily-available) drinks are best?

[400bhp]

I never said 40 on the flat, herp. 40 is a decent downhill. 30 or so is my top speed on a well surfaced flat when I am feeling good. By the way, I don't have a speedo, I just look at the speed of the cars and take a rough guess, which is pretty accurate in low traffic since car speed = speed limit (at least on the dual carriageways, because of fewer junctions). If I am keeping up with the cars on the middleway, then I'm doing approx 30mph.

Thanks for the warm welcome, though.

It's actually a sort of compliment that you guys find it so unbelievable that you turn into 4 year olds.

 

[400bhp]

:goofy voice:

BirmingHam alubohama,

 

[TheDoctor]

Right...
At 40 mph the weight of the bike is irrelevant. You're battling a brick wall of aerodynamics.
You're also putting out about 4 horsepower, which is Wiggo, Cav, Lance and Cav again, all rolled into one.
Basically, you're not doing 40 mph on the flat. That's utterly impossible.

 

[youngoldbloke]

What is a front cassette? Sounds awesome - I want one.

 

[vickster]

Perhaps he needs to study a bit harder for his physics GCSE...also I am guessing he has never driven a car so has no idea how fast people drive?

Good luck to him in the Rio Olympics however if this is all true

 

[mrandmrspoves]

Moses walked on water!

 

[Kookas]

Right...
At 40 mph the weight of the bike is irrelevant. You're battling a brick wall of aerodynamics.
You're also putting out about 4 horsepower, which is Wiggo, Cav, Lance and Cav again, all rolled into one.
Basically, you're not doing 40 mph on the flat. That's utterly impossible.

Again, never said I did 40mph on the flat (but that was interesting, so are you saying it isn't possible to do 40 on the flat even on a road bike? I was hoping that a road bike would be like an enormous step up from an MTB in all road conditions).

 

[martint235]

Again, never said I did 40mph on the flat (but that was interesting, so are you saying it isn't possible to do 40 on the flat even on a road bike? I was hoping that a road bike would be like an enormous step up from an MTB in all road conditions).

Ok I've been avoiding joining in. I'm not the quickest person I know but I've got a light road bike with 53/39 by 25/11 gearing and I also wouldn't say I'm a slouch but I can hit about 33mph on proper flat and hold it for about 500 yards.

A TdF rider is probably able to hold close to 40mph in the peloton

 

[cyberknight]

I managed to hit 35mph on my MTB (Trek 6000) and that was down a reasonably large hill, or as large as Suffolk has to offer anyway. It was way beyond pedalling out and I was tucking in as much as is possible on a MTB.

I can hit 30mph, albeit briefly, on the flat on my roadie, but sadly not 40mph, that is reserved for hills, dry weather and no obstacles.

All that said I do often manage to overtake car when riding on my Brompton in London, although I am not goign to make a comment about the speed of traffic in London

And finally, a heavier weight doesn't mean you descend faster. The laws of gravity apply equally and a heavy object will fall just as rapidly as a light one. Weight is only a penalty going up and is of no advantage going down. Has no-one seen the feather and hammer experiment on the moon landing

Thats for objects in a vacuum, for bike riding its slightly different so the upshot is that a heavier rider will go down hills quicker due to aerodynamic resistance which of course does not factor on the moon.
. Two objects of the same weight but with different surface areas will fall at two different rates, gravity didn't change. What we have is with the bike & rider is the same surface area with increased mass, therefore the speed of decent will have to increase due to the higher mass, the difference in speed is due solely because of the higher wind resistance needed to overcome the higher mass.
pasted from a forum with regards to the same question ...
"Gravity acting on an object equals a force (mass x acceleration). That force has to move the object (mass). A 1 kg object will have a gravitation force = 1kg x 9.8 meters/sec = 1 Newton. Now a 100kg object in the same situation will have a gravitational force of 100 Newtons. However, it takes 100x the force to move the 100kg object at the same acceleration. So in a vacuum they accelerate the same.

Let's add air resistance. Let's say these objects are roughly the same size and shape which causes air resistance = 1/2 Newton at a given speed. At that point in time the first object will have a net force acting on it of 1/2N and will accelerate a 4.9 meters/sec. The other object will have a net force on it of 99.5 Newtons and will accelerate at 9.31 m/s."
"the net force acting on the rider is F = m*g*sin(theta) - Fd, where m is the mass, theta is the slope angle, and Fd is the air drag. Now the acceleration is a = F / m = g*sin(theta) - Fd/m. The more you weigh, the closer you're going to come to the maximum acceleration g*sin(theta)"

 

[black'n'yellow]

Ok I've been avoiding joining in. I'm not the quickest person I know but I've got a light road bike with 53/39 by 25/11 gearing and I also wouldn't say I'm a slouch but I can hit about 33mph on proper flat and hold it for about 500 yards.

A TdF rider is probably able to hold close to 40mph in the peloton

one of the early season road races I was in, we hit 40mph - but that was in a large group of 50+ riders. Typical 1hr crit average is usually about 24-26mph, so the OP is doing well to be able to hold 30mph on his MTB.

 

[TheDoctor]

Again, never said I did 40mph on the flat (but that was interesting, so are you saying it isn't possible to do 40 on the flat even on a road bike? I was hoping that a road bike would be like an enormous step up from an MTB in all road conditions).

Yes, I am saying that. Think about it - a 50cc motorbike needs around 4hp to do 30 mph. 40mph needs about 5 hp. You, I, nobody does 5 hp.
Now, I've done close to 50 mph on a bike, but that was down a big hill with a good tailwind. On the flat - no way. No way on earth.

 

[Hacienda71]

Cav will hit mid 40's for a few seconds with a world class lead out. However he can output 1600watts in a sprint. He is also a world champion and one of the best road race sprinters that has graced this earth.

 

[mrandmrspoves]

Performance enhancing drugs......or in this case hallucinogenic drugs!

 

[Kookas]

Yes, I am saying that. Think about it - a 50cc motorbike needs around 4hp to do 30 mph. 40mph needs about 5 hp. You, I, nobody does 5 hp.
Now, I've done close to 50 mph on a bike, but that was down a big hill with a good tailwind. On the flat - no way. No way on earth.

... I'll repeat: I never said 40 on the flat (but bear in mind that a motorbike weighs more than a bicycle). I've already said that it takes a good hill to get near 40. 30 is doable, though. I'll mention that I didn't maintain this speed for miles, only from the point where I hit the middleway.

 

[black'n'yellow]

...30 is doable, though.

how long do you expect to be able to hold 30mph for...??