I guess this is a topic dear to most road rider's hearts! But I wonder if things have gone past the physics of the matter, into mere myth and custom?
I own a Softride Solo - a fairly heavy (14 kg) road bike. But it is very comfortable as it uses a carbon fiber suspension beam (no seat post). I have recently ridden a more normal and slightly lighter road bike, weighing in at 10kg. It was a LOT faster than the Softride, both on the flat and climbing hills.
I am trying to work out why so that I can either talk myself into buying a new bike, or so I can fix my Softride so that it is just as fast.
Argument 1 - Total weight (rider+bike)
Looking on the Softride website, I see they put forward the fairly reasonable argument that it is the complete weight of the rider, plus, bike, plus water bottle, mobile phone, etc that is important.
This seems a good scientific argument. If a rider weighs 100kg, and the bike 15 kg - total weight is 115kg. If we drop the bike weight to 10kg, this is only a total decrease in weight of 4% - no big deal.
Argument 2 - Bike weight alone
Most cyclists (And my local bike shop) assert that the bike weight is the big thing. Take off a couple of kilos on the bike, and you make a big difference in speed, etc. ie drop the weight from 15kg to 10kg. This is a drop in weight of 33% - a big change.
Never mind that you have a 110kg rider on the bike, loaded down with 2 kg water, mobile phone, digital camera, food bars, etc.
This does not make sense to me - but it has the advantage in that this seems to be what everyone has found to be true by experience. Or is it what they have heard at the bike shop, or read in bike magazines?
I have to admit that my slight experience shows me that the bike weight is the big thing. And it is what my local bike shop guy insists is the fact in real life.
Here was my "test" situtation.
Bike #1 - Softride Solo
Aluminium frame, 105 groupset, 700x23 wheels, flat handlebars. 14kg. Suspension beam seat post. Here in Australia costs around AUD$4,000. A road bike, but probably more of a tourer than a flat out speed machine.
Bike #2 - Raceline
Aluminium frame, Tiagra groupset, 700x23 wheels, dropdown bars. 10kg. Fairly cheap (entry level) road bike. Around AUD$1200.
Same rider (me), with basically the same equiment (ie water bottles, etc). The Raceline was MUCH faster than the Softride. Climbing hills was markedly easier on the Raceline.
So what do other people think? Is there a good scientific reason why the bike weight itself seems to be the over-riding factor? When it comes down to it - working out the physics of the matter is not so important to me - but is it true?
I own a Softride Solo - a fairly heavy (14 kg) road bike. But it is very comfortable as it uses a carbon fiber suspension beam (no seat post). I have recently ridden a more normal and slightly lighter road bike, weighing in at 10kg. It was a LOT faster than the Softride, both on the flat and climbing hills.
I am trying to work out why so that I can either talk myself into buying a new bike, or so I can fix my Softride so that it is just as fast.
Argument 1 - Total weight (rider+bike)
Looking on the Softride website, I see they put forward the fairly reasonable argument that it is the complete weight of the rider, plus, bike, plus water bottle, mobile phone, etc that is important.
This seems a good scientific argument. If a rider weighs 100kg, and the bike 15 kg - total weight is 115kg. If we drop the bike weight to 10kg, this is only a total decrease in weight of 4% - no big deal.
Argument 2 - Bike weight alone
Most cyclists (And my local bike shop) assert that the bike weight is the big thing. Take off a couple of kilos on the bike, and you make a big difference in speed, etc. ie drop the weight from 15kg to 10kg. This is a drop in weight of 33% - a big change.
Never mind that you have a 110kg rider on the bike, loaded down with 2 kg water, mobile phone, digital camera, food bars, etc.
This does not make sense to me - but it has the advantage in that this seems to be what everyone has found to be true by experience. Or is it what they have heard at the bike shop, or read in bike magazines?
I have to admit that my slight experience shows me that the bike weight is the big thing. And it is what my local bike shop guy insists is the fact in real life.
Here was my "test" situtation.
Bike #1 - Softride Solo
Aluminium frame, 105 groupset, 700x23 wheels, flat handlebars. 14kg. Suspension beam seat post. Here in Australia costs around AUD$4,000. A road bike, but probably more of a tourer than a flat out speed machine.
Bike #2 - Raceline
Aluminium frame, Tiagra groupset, 700x23 wheels, dropdown bars. 10kg. Fairly cheap (entry level) road bike. Around AUD$1200.
Same rider (me), with basically the same equiment (ie water bottles, etc). The Raceline was MUCH faster than the Softride. Climbing hills was markedly easier on the Raceline.
So what do other people think? Is there a good scientific reason why the bike weight itself seems to be the over-riding factor? When it comes down to it - working out the physics of the matter is not so important to me - but is it true?