What makes a good descender?

[ColinJ]

I'd taken Yellow Fang to mean that he couldn't physically go fast enough on a fairly gentle non-technical descent. The technical stuff is something else altogether.

Fast technical descending requires two things - skill and courage, and I don't have enough of either! A mate of mine does, and it is scary but fascinating to watch him in action. I can't believe how far he banks over sometimes... When we first started riding together I used my lard-power to gain about 200 metres on him on a long descent which led to some bends further down. I was braking way in advance of a tight left-hander when suddenly the Kamikaze nutter dived past on my inside and just laid his bike over. I was so shocked that I went straight on and almost hit the wall opposite. After that I always chose to follow him downhill.

 

[HLaB]

I'm a terrible descender also. With me its not because of weight, although I'm quite light (10,3 I think), its because I'm too nervous.

 

[Tynan]

always been quick downhill me, can free wheel past people

I am 14st9lb and used to be a lot heavier

 

[Dave5N]

STill don't understand the weight thing. What was Galileo on about then?

 

[col]

I think if your bike is in order,the best thing to do is try to make as small an area for the wind or air to catch,wrap yourself round the bike,and get as low as you can.But knowing the hill,and or having the balls for it can make a big difference.

 

[Chris James]

STill don't understand the weight thing. What was Galileo on about then?

What don't you understand about the weight thing?

All riders when they start to descend a hill will accelerate at the same rate due to gravity.

However, your maximum speed is limited (so called terminal velocity) and this is prediominantly due to wind resistance slowing you down and preventing you from endlessly accelarating.

Imagine two riders freewheeling down a hill.

At terminal velocity the forward forces are equal to the backward forces, so you no longer speed up but just maintain your existing speed.

But the gravitational force driving you forward is the mass of the rider x gravitational acceleration. So a rider who weighs 25% more will have 25% greater forward force but the wind resistance at terminal velocity would have to be 25% more too. Since wind resistance is related to frontal area and speed (but not mass of the rider) then the heavier rider will attain a higher terminal velocity - assuming they have the same frontal area.

This effect is particularly visible on tandems where the front area is similar to a solo cyclist's but the weight of the tandem and riders is approximately double that of a solo rider.

 

[Fab Foodie]

What don't you understand about the weight thing?

All riders when they start to descend a hill will accelerate at the same rate due to gravity.

However, your maximum speed is limited (so called terminal velocity) and this is prediominantly due to wind resistance slowing you down and preventing you from endlessly accelarating.

Imagine two riders freewheeling down a hill.

At terminal velocity the forward forces are equal to the backward forces, so you no longer speed up but just maintain your existing speed.

But the gravitational force driving you forward is the mass of the rider x gravitational acceleration. So a rider who weighs 25% more will have 25% greater forward force but the wind resistance at terminal velocity would have to be 25% more too. Since wind resistance is related to frontal area and speed (but not mass of the rider) then the heavier rider will attain a higher terminal velocity - assuming they have the same frontal area.

This effect is particularly visible on tandems where the front area is similar to a solo cyclist's but the weight of the tandem and riders is approximately double that of a solo rider.

Agreed.
In a vacuum both riders regardless of weight will descend at the same speed.
In a vacuum, a feather and a cannonball will fall at the same rate. When they hit the ground at the same moment, the cannonball will make a big dent whereas the feather will not...this is the force effect due to the greater mass of the cannonball.
Overcoming the force due to the wind is where weight matters... all other things being equal.