Planing

[PurpleFrog]

http://georgenaterry.com/steel-bike-weighing-9-6-lbs-more-than-titanium-bike-climbs-just-as-well/

..a real world test: two guys racing each other up the same hill, one on the ti bike, one on the steel. They swapped out the bikes several times. Both were evenly matched in terms of strength, endurance and weight.

The weight of a steel bike is always of interest. This steel bike was 9.6 lbs heavier than the ti bike, but it climbed as well. It sounds implausible, but as Jan explained, when the weight of the riders was taken into account, the steel bike plus rider was only 5% heavier than the ti bike plus rider, but the steel bike “planed”, helping the rider generate the extra power needed to overcome the weight difference.

Fans of Jan’s bike testing will know there is an advantage to a bike that “planes”. This is a bike that is in synch with the rider and flexes in a way that “gives back” some of the rider’s energy to the drivetrain.

There's more technical stuff here:

http://janheine.wordpress.com/2011/10/0 ... stiffness/

http://janheine.wordpress.com/2011/02/2 ... stiffness/

...Does this make sense to anyone here and have they noticed any frames that seem to give an extra boost to pedaling? I have a suspicion that the GT crossover might cause the rear triangle to used (unintentionally) to get the same benefit.

 

[velofrog]

Re:

i saw it fleetingly as it passed waaaaaaay over the top of my head..... :shock:

 

[NeilM]

Re:

9.6lbs heavier! What was it made of, cast iron!

I have a carbon road bike that weights 8kg / 17.6lbs I have a steel road bike that weighs the same.

I have an alloy 29'er that weighs 9 kg / 19.8lbs.

Most of my retro steel mtbs weigh around 11 to 12kgs / 24 to 26lbs which would mean the Ti bike in this example weighed 16.4lbs or 7.45kgs... that's a light bike, whatever it's made of.

 

[The History Man]

It doesn't mean that. Both bikes could be proportionally heavier than yours actually.

 

[NeilM]

Both bikes could be proportionally heavier than yours actually.

True, but a 9.6lb difference between two comparable bikes is still huge.

 

[PurpleFrog]

Re:

I remember finding a paper somewhere that showed there were differences between the amount of energy a bicycle frame would return when used as a spring.... The work had been done at some UK university.

 

[Rod_Saetan]

The Prof touches on it here: http://www.compint.com/stinkingweasels/ ... ffness.htm - given common accepted frame design is 'stiffness is everything' (in the BB/drive area) it makes intriguing reading.

 

[PurpleFrog]

Re:

That's terrific - I though Trek's lawyers had removed all of Bontrager's "Rants" from the Net (as they can very often be used to undermine Trek marketing.)