Peteaud
Veteran
- Location
- South Somerset
I think i am slower due to my gut acting like a parachute. 
Don't believe what they all say about "weight".
- Thread starter gavroche
- Start date
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gam001
Über Member
Roadhump
Time you enjoyed wasting was not wasted
- Location
- The flatlands of South West Lancs
I'm a 5' 9", 15 stone stocky guy, quite powerful but with a bit of a beer belly. My weight has been up and down over the years though. I find age is also a performance inhibitor. I am almost 53 now and just cannot reach the average speeds I used to to reach 15 years ago (I have an old file on which I recorded some from that time - a bit geeky, I know). 20 years ago I used to make it to the top of a hill about 8.5 miles away in 30 minutes on an inferior bike to the one I now use, but now it takes me about 35 minutes.
Cycleops
Legendary Member
- Location
- Accra, Ghana
I know the feeling, and it takes you all night to do what you used to do all night!
Shut Up Legs
Down Under Member
I'm a faster cyclist and better climber than I was at 20 (I'm now 45). Youth was wasted on me, I'm afraid. I'm sure I could have been a much better cyclist back then if I'd only bothered to work on it.
Crankarm
Guru
- Location
- Nr Cambridge
Yeah, but to be a fast cyclist over most terrain you have to be lighter and stronger. So power to weight ratio is important. Even a sprinter like Cavendish is pretty thin compared to most of the Joes riding on here who claim fat and fit is fine and climbers KOM riders are like skellingtons compared to nearly every plodder on here. It's not just visible fat but fat around your vital organs that counts and fat that silts up the arteries. Eat less crap, moderate portion size, ride harder, more frequently and for longer.
Crankarm
Guru
- Location
- Nr Cambridge
Depends what you define as "fit". Moving to the kitchen to grab another pack of Doritos whilst watching the TdF might qualify but if you wish to do any intense sustained sporting activity then, no.
Shovelling in the pies just because you ride 1 mile to work and back each day and weighing 15+ stones does not mean you are fit. You are a heart attack waiting to happen, not to mention a candidate for diabetes with all the Coke you'd drink and cakes you'd probably eat as well.
Rob3rt
Man or Moose!
- Location
- Manchester
There are several things that ought to be recognised.
On the flat, power to weight is largely irrelevant, power to CdA is the dominant factor to how fast you will go. The frontal area of a heavier and a lighter rider is generally not that different (within reason, discounting extremes) so the rider with the highest absolute sustainable power (for the relevant duration) will often be quickest.
The reason that many heavier, more muscular riders are okay on the short steep stuff is because generally the heavier riders are relativelly very powerful and/or explosive (i.e. short duration power output is very high) thus they can put out a lot of power for the shorter duration to get up the short climbs with the bunch. As the hills gets longer they suffer though as a typical sprinter has a distinctly downward sloping power profile (i.e. power drops off sharply the longer the duration) so they will fatigue and slow substantially. It is here that your power to weight ratio (as most seem to refer to it) really starts to dominate.
Of course in the grand scheme of things, being as light as possible while being as powerful as possible is desirable, why carry something you don't need (plus having less fat has benefits other than reduced weight) but the reality is, depending on your discipline you will need to compromise, i.e. if you are a climber, you will need to give up some power to get light, if you are a sprinter, you will need to get heavier to gain explosive power, etc.
It should also be noted being powerful is not the same thing as being strong!
On the flat, power to weight is largely irrelevant, power to CdA is the dominant factor to how fast you will go. The frontal area of a heavier and a lighter rider is generally not that different (within reason, discounting extremes) so the rider with the highest absolute sustainable power (for the relevant duration) will often be quickest.
The reason that many heavier, more muscular riders are okay on the short steep stuff is because generally the heavier riders are relativelly very powerful and/or explosive (i.e. short duration power output is very high) thus they can put out a lot of power for the shorter duration to get up the short climbs with the bunch. As the hills gets longer they suffer though as a typical sprinter has a distinctly downward sloping power profile (i.e. power drops off sharply the longer the duration) so they will fatigue and slow substantially. It is here that your power to weight ratio (as most seem to refer to it) really starts to dominate.
Of course in the grand scheme of things, being as light as possible while being as powerful as possible is desirable, why carry something you don't need (plus having less fat has benefits other than reduced weight) but the reality is, depending on your discipline you will need to compromise, i.e. if you are a climber, you will need to give up some power to get light, if you are a sprinter, you will need to get heavier to gain explosive power, etc.
It should also be noted being powerful is not the same thing as being strong!
wait4me
Veteran
- Location
- Lincolnshire
(I have an old file on which I recorded some from that time - a bit geeky, I know).
Old files are like us --they lose their cutting edge over the years. Was going to put something about bastard in here but couldn't think of a link
Old files are like us --they lose their cutting edge over the years. Was going to put something about bastard in here but couldn't think of a link
400bhp
Guru
What does that mean?
Rob3rt
Man or Moose!
- Location
- Manchester
CdA = drag co-efficient which is largely dependant on your position on the bike and equipment choices. It is also not static and varies with yaw angle.
Flat speed would be a compromise between being aero and being powerful, to get more aero, it usually involves getting lower and narrower at the front end. Both things which compromise power (either by closing the hip angle or by constricting your chest). So you need to balance how aero you are with how much power you put out.
Flat speed would be a compromise between being aero and being powerful, to get more aero, it usually involves getting lower and narrower at the front end. Both things which compromise power (either by closing the hip angle or by constricting your chest). So you need to balance how aero you are with how much power you put out.
Rob3rt
Man or Moose!
- Location
- Manchester
I also forget to mention in my rather long post, people seem to refer to power to weight ratio as a single figure, this is not the case, power to weight ratio varies with duration (unless you are a Duracell bunny and are either on or off and your power is constant across all durations)!
400bhp
Guru
Long time since I did physics, but have done a bit of research around motor racing.
So, co-efficient is between zero and 1 is it? What's the formula that incorporates mass/acceleration/speed? (combination). What's "yaw" for a bike?
Rob3rt
Man or Moose!
- Location
- Manchester
I think CdA can be greater than 1. Formula is given on the Wikipedia page: http://en.wikipedia.org/wiki/Drag_coefficient
Yaw is the effective incident wind angle as far as I understand (function of wind angle and speed?).
The following may be interesting: http://anonymous.coward.free.fr/wattage/cda/indirect-cda.pdf
It is a way to estimate CdA using a power meter, Golden Cheetah has this method built into a nice GUI called Aerolab, it also covers the equations and any assumptions and simplifications, apparently this method is quite good and has good sensitivity, there are a few variations out there too.
GrasB is your man for this stuff, or get yourself over to the Wattage group or TTF.
There is never a day with little to no wind here, so I haven't had the chance to give this a go. I will do at some point though. I think my club mate has done some testing of this type on the velodrome. I think he was testing helmets and I seem to think the KASK Bambino won (not to say it is the best helmet, but the best fit for him and his ride position, in those conditions, he uses a Bambino and another helmet on the road, seems to vary which he uses).
Yaw is the effective incident wind angle as far as I understand (function of wind angle and speed?).
The following may be interesting: http://anonymous.coward.free.fr/wattage/cda/indirect-cda.pdf
It is a way to estimate CdA using a power meter, Golden Cheetah has this method built into a nice GUI called Aerolab, it also covers the equations and any assumptions and simplifications, apparently this method is quite good and has good sensitivity, there are a few variations out there too.
GrasB is your man for this stuff, or get yourself over to the Wattage group or TTF.
There is never a day with little to no wind here, so I haven't had the chance to give this a go. I will do at some point though. I think my club mate has done some testing of this type on the velodrome. I think he was testing helmets and I seem to think the KASK Bambino won (not to say it is the best helmet, but the best fit for him and his ride position, in those conditions, he uses a Bambino and another helmet on the road, seems to vary which he uses).
