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Advice on descending for very small people

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  • mamba80mamba80 Posts: 5,032
    At only 5' 4'' and 58kg, I'm one of the smallest in my club, but one of the fastest decenders when the doing get twisty. The single biggest difference, is that I always look way through the corner and the path I want to take, stay relaxed and let the bike do the work. Being small also means that you have less frontal area, which should make up for your lack of mass.

    Another misconception is that gravity is somehow responsible for making heavier riders to descend faster, it's not. The greater mass just means you have more momentum (momentum = mass x velocity) for wind resistance to act against. All else being equal, objects of different mass will fall at the same rate.

    you may indeed be a demon descender but a rider of 80kg coming out of a corner at the same speed as a rider weighing 50kg will go away from him/her, also, a smaller rider will get blown about a lot more.

    Wind resistance may make a difference but it wont over come the effects of gravity - we used to run a hill climb, after everyone had gotten up, we d do a freewheel, no pedalling, roll down into a U shaped descent, without the fail, the heaviest rider always got the furthest up the other side.
  • DKayDKay Posts: 1,652
    At only 5' 4'' and 58kg, I'm one of the smallest in my club, but one of the fastest decenders when the doing get twisty. The single biggest difference, is that I always look way through the corner and the path I want to take, stay relaxed and let the bike do the work. Being small also means that you have less frontal area, which should make up for your lack of mass.

    Another misconception is that gravity is somehow responsible for making heavier riders to descend faster, it's not. The greater mass just means you have more momentum (momentum = mass x velocity) for wind resistance to act against. All else being equal, objects of different mass will fall at the same rate.

    you may indeed be a demon descender but a rider of 80kg coming out of a corner at the same speed as a rider weighing 50kg will go away from him/her, also, a smaller rider will get blown about a lot more.

    Wind resistance may make a difference but it wont over come the effects of gravity - we used to run a hill climb, after everyone had gotten up, we d do a freewheel, no pedalling, roll down into a U shaped descent, without the fail, the heaviest rider always got the furthest up the other side.

    At the end of the day, all depends on what frontal area you are presenting to the air in relation to the combined mass of the rider and bike and the velocity you are going at, as drag increases to the square of velocity. But please stop talking about the 'effects of gravity'. Gravity isn't a factor for making a rider with more mass descend down an incline faster than a rider with less mass (all other things being equal).
  • mamba80mamba80 Posts: 5,032
    We will have to agree to disagree on this, we both have different views and experiences, on the effects of weight and gravity.
  • lostboysaintlostboysaint Posts: 4,252
    At only 5' 4'' and 58kg, I'm one of the smallest in my club, but one of the fastest decenders when the doing get twisty. The single biggest difference, is that I always look way through the corner and the path I want to take, stay relaxed and let the bike do the work. Being small also means that you have less frontal area, which should make up for your lack of mass.

    Another misconception is that gravity is somehow responsible for making heavier riders to descend faster, it's not. The greater mass just means you have more momentum (momentum = mass x velocity) for wind resistance to act against. All else being equal, objects of different mass will fall at the same rate.

    you may indeed be a demon descender but a rider of 80kg coming out of a corner at the same speed as a rider weighing 50kg will go away from him/her, also, a smaller rider will get blown about a lot more.

    Wind resistance may make a difference but it wont over come the effects of gravity - we used to run a hill climb, after everyone had gotten up, we d do a freewheel, no pedalling, roll down into a U shaped descent, without the fail, the heaviest rider always got the furthest up the other side.

    At the end of the day, all depends on what frontal area you are presenting to the air in relation to the combined mass of the rider and bike and the velocity you are going at, as drag increases to the square of velocity. But please stop talking about the 'effects of gravity'. Gravity isn't a factor for making a rider with more mass descend down an incline faster than a rider with less mass (all other things being equal).


    Isn't it? What's the force acting on the rider that causes the acceleration then? Has someone "done a Hawking" on Newton's first law (the inertia one) and proven it wrong?
    Trail fun - Transition Bandit
    Road - Wilier Izoard Centaur/Cube Agree C62 Disc
    Allround - Cotic Solaris
  • diydiy Posts: 6,680
    Dkay is correct only in a vacuum. The issue is rider mass is not proportional to area exposed to drag. Thus all things being equal (on this planet at least), the heavier rider will descend faster.
  • DKayDKay Posts: 1,652
    Isn't it? What's the force acting on the rider that causes the acceleration then? Has someone "done a Hawking" on Newton's first law (the inertia one) and proven it wrong?

    You are missing the detail. For object of different masses, there is no difference in their acceleration due to gravity. The reason a rider with more mass descends faster is due to fact that they have greater momentum, which overcomes the opposing force of aerodynamic drag / friction.
  • mamba80mamba80 Posts: 5,032
    Isn't it? What's the force acting on the rider that causes the acceleration then? Has someone "done a Hawking" on Newton's first law (the inertia one) and proven it wrong?

    You are missing the detail. For object of different masses, there is no difference in their acceleration due to gravity. The reason a rider with more mass descends faster is due to fact that they have greater momentum, which overcomes the opposing force of aerodynamic drag / friction.

    who gives a xxxx ? this a cycling forum not a Physics forum.... its gravity taking me down the hill faster than Mr Skinny Pants...Momentum? Gravity ? all the same to me as it does the same job.
  • lostboysaintlostboysaint Posts: 4,252
    Isn't it? What's the force acting on the rider that causes the acceleration then? Has someone "done a Hawking" on Newton's first law (the inertia one) and proven it wrong?

    You are missing the detail. For object of different masses, there is no difference in their acceleration due to gravity. The reason a rider with more mass descends faster is due to fact that they have greater momentum, which overcomes the opposing force of aerodynamic drag / friction.

    Nope, you just moved the goalposts.
    Trail fun - Transition Bandit
    Road - Wilier Izoard Centaur/Cube Agree C62 Disc
    Allround - Cotic Solaris
  • overlord2overlord2 Posts: 336
    I don't think size has got a lot to do with descending - it's primarily about bottle followed by technique - plenty of very light pro riders manage to descend well.

    On UK roads size does have a lot to do with it. UK decents are bumpy, windy, lots of tight turns with blind corners on very narrow roads, sheep and lambs in road. Hence it is impossible to get any momentum. Heavy riders will have the pull of gravity.

    Get me on an alpine decent I can match most people. Long decents and sweeping corners are not very technical.

    Decending fast in the UK is pretty much suicidal eventually you will end up in a tractor, car, sheep, cow, stone wall, pothole or a tandem accending that 20% gradient.
  • lesfirthlesfirth Posts: 1,147
    Isn't it? What's the force acting on the rider that causes the acceleration then? Has someone "done a Hawking" on Newton's first law (the inertia one) and proven it wrong?

    You are missing the detail. For object of different masses, there is no difference in their acceleration due to gravity. The reason a rider with more mass descends faster is due to fact that they have greater momentum, which overcomes the opposing force of aerodynamic drag / friction.

    who gives a xxxx ? this a cycling forum not a Physics forum.... its gravity taking me down the hill faster than Mr Skinny Pants...Momentum? Gravity ? all the same to me as it does the same job.

    Some people should keep their opinions to themselves. :roll:
  • pinnopinno Posts: 41,599
    When I get to the top of a hill, I pick up a strategically placed breeze block to help me descend quicker. The only problem is that it really does make a mess of the paintwork.

    FWIW and way off topic. Is it me or is everyone a bit tetchy on the BR forum? This is usually silly season but it is an altogether different sort of silly season at the moment. Can we blame the weather?
    seanoconn - gruagach craic!
  • diydiy Posts: 6,680
    The training fitness and health forum is usually like this. :D As long as you stick to the following unwritten rules you'll be fine:

    1. only qualified sports coaches may comment on training.
    2. only thin people can give diet advice
    3. if you are not training to race, move along nobody cares about your goal
    4. suggesting any method of training that doesn't involve riding your bike is satanic worship
    5. the laws of physics don't matter.

    The above said tongue in cheek, its actually not a bad place to discuss stuff with people who've actually thought about it for more than 5 mins. :D
  • roger_merrimanroger_merriman Posts: 6,157
    Hi All

    Would really like some ideas on improving my descending. I'm reasonably experienced, do sportives, race the odd crit, keep up fine with the clubrun BUT I'm 5' tall and 49 kg, and when it comes to proper descending I can't hold the pace or sweep of the 'average' competent male club rider. Yeah I know they are 75kg and 6', but a. I lack bottle b. they seem more planted on the road - I feel light and skippy. Have experienced this particularly on mountain descents e.g.Italian GFs where if I hit a windy section, everything gets nervous. I've noticed my smaller, lighter male riding companions also suffer more than the larger guys. Is it just a size/weight differential thing? I've done the bikefit, cornering techniques etc so I'm comfortable, not overstretched, in the drops, low and relaxed arms, decent bike (Spesh Amira which is equiv of Tarmac for us hobbits), not overdeep rims (about 26- 30mm), generally running Conti GP4000s at about 100 psi in the dry. What can I do better or different, or should I just eat more pies? thanks!

    clearly weight does help.

    I'm 90KG and until recently had various SS bikes which I could still leave most behind on the downs.

    have to say normally I don't since most uk descents you can't see though the bends, so just roll.

    some bikes are more twitchy than others. wider softer tyres can't hurt for sure.

    how often are you descending properly? unless you feel your loosing a lot of time/unsafe i'd not worry about it that much. The times down are much less so, even if you where a shocking descender the time lost is much less compared to the climb.
  • JonnyyorksJonnyyorks Posts: 13
    Does this relate to straight downhill or corners? I notice you are calling out twitchiness and nerves so that is clearly a confidence issue. I'm not the heaviest rider (72Kg) but I roll very well and have no problem keeping up with much heavier riders on freewheeling descents. I guess the question is why?, and to be honest I don't know, but would guess at the following:
    Confidence. I'm very relaxed on the bike and my heart rate drops very low as soon as I start descending. I do believe if you are nervous you hold on a lot tighter and feel everything the environment has to offer. As soon as you feel it you start to worry about it and a set of defensive factors kick in

    Most of all you need to go through the uncomfortable zone and this I think is a mental challenge. You need to up your speed gradually on different gradients of hills until higher speed becomes normal and the twitches don't register. It is highly unlikely that a twitch will throw you, but if you are feeling it the chances are you are sitting up, grabbing on to the bars, stiffening your body and reaching for the brakes. All of these are things that will slow you. The reality is that everyone gets those twitches, no matter how heavy they are, but are sensitive to them to a different degree. The less sensitive you are the more confident you will be. The chances are what you think is a big movement will be almost invisible to the eye, it is just your head magnifying the effect. Like driving a car 50mph seems ridiculously fast at first, then the brain normalises it and then it feels slow.

    - braking. Using brakes downhill is dangerous as the chances of twitching, locking etc get greater at higher speeds. As such I don't brake ever on a downhill unless I need to negotiate a corner. If I do need to slow down (it would be a corner) I sit up high to start with and use my body as a windbrake before applying the brakes. This does two things, it gets your body into a more natural braking position with good weight distribution and it scrubs some of the speed before the pad hits the rim. It's amazing how effective the body is as a brake (even if you are small).
    - not being aero. I get down behind the stem to present a small of footprint as possible. Clearly this is an unstable position in anything but the straightest of straight lines; it does work though. To do this I think you have to be comfortable moving you body around the bike at high speed and you need to have the confidence to move your fingers away from the brakes to a degree. This is something that should be easier for a smaller rider.
    - for technical descents you need to read the road well, choose your line and brake smart. A lot of road riders don't look that far ahead due to riding position, but this makes for slow descending in my opinion. You need to get your eyes forward, scan the road for obstacles and corners, choose your line and then hand over to your subconscious to negotiate them. A very good motorcycle racer taught me that your subconscious decision making is much faster than your conscious so let your eyes worry about the road ahead and your head worry about what is in front of your wheel (your eyes provided this information seconds earlier)
    - braking, only ever do it in a straight line and the pressure on the brakes should be exactly as your head calculated. If it isn't and you are slamming on or slowing up to quickly, your judgement isn't matching your ability or your brakes aren't calibrated to your riding style
    - cornering. Don't worry about the bike or the direction. You should already have worked out your line and therefore your speed and lean angle so let your head take over and work out how to achieve it. I don't think I've ever thought about where my handlebars are pointing at any given moment, but I do think about lean angle in relation to road surface and conditions. I personally like to jam pressure onto the outside pedal when leaning into a corner in general, but more so on descents as they tend to be faster. You need the edge of the tyre to hold and that helps in my opinion.
  • pinnopinno Posts: 41,599
    The training fitness and health forum is usually like this. :D As long as you stick to the following unwritten rules you'll be fine:

    1. only qualified sports coaches may comment on training.
    2. only thin people can give diet advice
    3. if you are not training to race, move along nobody cares about your goal
    4. suggesting any method of training that doesn't involve riding your bike is satanic worship
    5. the laws of physics don't matter.
    6. Posts exceeding 8 words is heresy and
    7. Using words that contain more than 2 syllables is a capital offence.

    The above said tongue in cheek, its actually not a bad place to discuss stuff with people who've actually thought about it for more than 5 mins. :D

    FTFY
    seanoconn - gruagach craic!
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