Better descending - the weight factor.

Peddle Up!

I'm still working on improving my descending technique (see previous posts here ad nauseum), if only to save money on brake blocks. I'm a large rider (but not fat, I like to think ) at 6' 3" and 15 st and I've noticed that many of the really fast downhill merchants are small and (presumably) light.

Of course gravity is going to pull on me more to increase my speed, but I believe a real limiting issue is what happens when you hit a rough patch on the road - not always a pothole, sometimes just a bit of a ridge or similar. Despite being off the saddle, and keeping a light grip on the bars, it really shakes the bike and makes me feel less stable - cue dab of braking at speed.

What's the experience of other similarly sized riders. Any tips for dealing with this? Thanks.

BobScarle

Gravity acts equally on all objects irrespective of weight. Some people just seem to descend faster than others. Maybe it's due to frontal area, air resistance, etc.

Rough ground at speed can be a nightmare and nothing much you can do, other than what you have said. Use the brakes, that's what they are there for, but be careful. The ground can make the bike unstable, as well as uncomfortable, and any sudden movement, braking or steering, could be catastrophic. I try to avoid the rough, if possible, slow down if I can, or relax and hope if the others fail.

rick_chasey

On a long, straight downhill - heavier riders will decend quicker since they have a higher force due to gravity pushing the air out of the way.

However, as soon as it twists and turns you'd expect a lighter rider to be quicker - less to brake, less to turn, less to accelerate.

Speller78

I'm taller and (slightly) heavier than a friend i ride with and he descends much faster than me. I think it is a combination of his smaller frontal area and the fact that i'm a big girl's blouse.

mousetoo

BobScarle wrote:

Gravity acts equally on all objects irrespective of weight. Some people just seem to descend faster than others.

Dredging up my A-level physics, but this isn't true is it? Weight is the effect of gravity on mass. So higher mass, higher weight

Peddle Up!

mousetoo wrote:

BobScarle wrote:

Gravity acts equally on all objects irrespective of weight. Some people just seem to descend faster than others.

Dredging up my A-level physics, but this isn't true is it? Weight is the effect of gravity on mass. So higher mass, higher weight

All objects experience the same acceleration due to gravity, irrespective of mass. My mistake. :roll: I'd just eaten a pasty which explains it, I guess.

rick_chasey

Peddle Up! wrote:

mousetoo wrote:

BobScarle wrote:

Gravity acts equally on all objects irrespective of weight. Some people just seem to descend faster than others.

Dredging up my A-level physics, but this isn't true is it? Weight is the effect of gravity on mass. So higher mass, higher weight

All objects experience the same acceleration due to gravity, irrespective of mass. My mistake. :roll: I'd just eaten a pasty which explains it, I guess.

For sure.

But as you know on earth, you drop a tonne of feathers and a tonne of stones, the stones will hit the ground sooner because of air resistance.

rolf_f

If you think mass makes no difference then how about we have a vehicle pushing contest down a gentle slope. I'll push my bicycle and the other can push a truck!

The truck will take longer to get moving but it will eventually manage a higher velocity.

smidsy

The only thing that affects how fast something is moved by gravity is another force (e.g. friction), not the weight of the object.

Remember Galileo anyone?

racingcondor

It sounds like your biggest problem is confidence. You could probably improve your aerodynamics and the confidence may be improved by making changes to your bike/position on the bike that improve it's stability if you find it twitchy at speed (but there are soo many factors involved in that that I'm not going to hazard a guess).

Peddle Up!

racingcondor wrote:

It sounds like your biggest problem is confidence. You could probably improve your aerodynamics and the confidence may be improved by making changes to your bike/position on the bike that improve it's stability if you find it twitchy at speed (but there are soo many factors involved in that that I'm not going to hazard a guess).

Yep, it's confidence. Keep plugging away, I guess. :?

cougie

If you're descending at speed you want to be further out into the road - go where the car tyres go - away from the rough stuff at the side. You're more visible and you have more road to play with. Speed is usually your friend. Braking and rough road surfaces aren't a good mix.

I'm no scientist but I've always found my heftier pals descend a lot faster than the lighter ones. Freewheeling obviously.

I'm not sure about freefalling.

rake

gravity accelerates at the same rate in freefall, but you're not riding off a cliff. there is a forward component from downward force against the non verticle slope. more downward weight = more forward force which overcomes air resistance better.