Bike weight vs Body weight

[Eldron]

I honestly don't think i'ts down to air resistance that makes the heavier rider slower up the hill. Friction between the bike and the ground needs to be taken into consideration where the friction on an object is directly related to the force exerted on the object ie. The downwards force of the weight of the rider.

 

So with all things being equal, the heavier rider has to work harder to not only move the weight up hill, but he needs to exert more power to overcome the friction force.

 

Here is a cool quote I got from this article: https://tunedintocycling.com/2014/06/28/aerodynamics-part-1-air-resistance/

 

 

What would riding a bike be like if you didn’t have to overcome air resistance? Reading from the graph, it takes about 100 watts of power to overcome the combination of rolling, drive and air resistance when you’re going 25 kph (15.5 mph). If you take air resistance out of the equation and imagine the linear functions for rolling and drive resistance extending beyond the 50 kph boundary on the right side of the graph and continuing to increase at roughly the same rate, that same 100 watts of power would be sufficient to move you forward (on a very rough estimate) at a speed of about 125 kph (77.7 mph).

[dave303e]

to counter the argument that bike weight makes it handle better see video below- these bikes all weigh over 100kg.

 

If you want to cycle faster lose the body fat...

 

[ChrisF]

Okayyyyyy .....

 

It IS Friday, so lets stir this pot a bit ....

 

 

DRAG - this is a function of "projected area" and "the square of the velocity", and a few other things.  Sorry, but your "projected area" wont change that much if you loose 5 or 10kg .... so the PRIMARY contributor to drag force is the velocity.  Double your velocity and drag increases four fold !!!  Not that this is a real issue for the speed at which us mere mortals climb steep hills though .... so really not worth faffing about this.

 

 

MASS - for the moment lets look at "equivalent mass", thus combining  "linear and rotational" mass via some fancy maths.  There are two distinct different situations to consider :

1) CONSTANT velocity - going up a hill at constant velocity there are basically two forces to consider, ie the weight component (Fg) and the friction component (Fr).  Fr is mostly constant, and wont change noticably for a few kilograms to a side.  Now consider the mass component, let's say rider and bike has an equivalent mass of 100kg.  For a typical grade 1:10, you can effectively add another 1,7N of force to drag you up the hill, translating to about 4,7W at a mere 10km/h ... yada yada .... it is a LINEAR equation !  So if you can reduce your mass by 10%, you can SAVE 10% of your energy going up hill !!  Or, like your skinny buddies, you can fly up the hills for the same energy input.

 

2) Accelerating - No the maths becomes just a little more complex, as the rotational masses have a bigger impact than the non-rotational masses ....  Significant advantages to lightweight rims and very light tires, much more so than saving grams on ultra-light weight gears .... yada yada .....not so easy to come suck a single figure showing savings here in weight loss.  But since the bulk of the time spent going uphill is done at virtually constant speed this is just a handy excuse to justify those lightweight rims ....

 

 

so all said and done, drop a few pounds or a few Pounds to get up that hill easier ....  

[NoirBiker]

Pizza and beer is why I ride. and Steak and Boerewors and Pork rashers... and beer...

I eat those but I still weigh 54kg  except the pizza , granted I run a lot, commute daily to work for 20km plus a 4 km walk into the plant and do weekday and weekend rides so yeah. When I started cycling I was weak, a moderately fat bloke would beat me on the climbs easily until I put effort, trained hard and learned a lot of mtb and cycling skills now climbing is my forte but my sprinting could be better so in retrospect a light weight cyclist without effort and training is as good as nothing on a superlite bike.