"What's the steepest gradient for a road bike?"

charliew87

Interesting piece by wired in response to Cav's tweet wondering how steep a slope it's possible to cycle up after the Tirreno monsters.

http://www.wired.com/wiredscience/2013/03/whats-the-steepest-gradient-for-a-road-bike/

Beckers62

viewtopic.php?f=40013&t=12910129

One I made earlier ;-)

binkybike

charliew87 wrote:

Interesting piece by wired in response to Cav's tweet wondering how steep a slope it's possible to cycle up after the Tirreno monsters.

http://www.wired.com/wiredscience/2013/03/whats-the-steepest-gradient-for-a-road-bike/

I think he has underestimated the possible power of a pro cyclist (for relatively short climbs anyway) and overestimated the friction, once the back wheel starts slipping you are doomed, although this depends on tires, surface and conditions.

Not that I have sums to back that up of course.

navrig

binkybike wrote:

charliew87 wrote:

Interesting piece by wired in response to Cav's tweet wondering how steep a slope it's possible to cycle up after the Tirreno monsters.

http://www.wired.com/wiredscience/2013/03/whats-the-steepest-gradient-for-a-road-bike/

I think he has underestimated the possible power of a pro cyclist (for relatively short climbs anyway) and overestimated the friction, once the back wheel starts slipping you are doomed, although this depends on tires, surface and conditions.

Not that I have sums to back that up of course.

I agree. I think a powerful pro cyclist who specialises in climbs would run out of traction of the steepest hill before he ran out of oooomph.

joe.90

cav probably tweeted that on a wimb and within a day someone has analyzed it to the nth degree!

slowbike

Well - on the track Geraint Thomas produces
Max 1250watts
Average 800watts
for 4k in 3 min 53.3 seconds.


Assuming the max is the acceleration from start so it's only a (relatively) brief reading we can forget that ...
but he's averaging 800watts - I wonder how well he'd go up a 45% gradient ... he'd have the power ...



(feck - I'd like to reach max 800 watts - no chance of averaging that!)

bompington

You don't need much power to go up a 45% gradient - if you can do it slowly. No hard scientific calculations or evidence to offer but I'm fairly sure that traction is the limiting factor in most cases.

gezebo

Are we talking about standard geometries or custom made bikes??

Cleat Eastwood

heres a mtb going up scannupia @45%

http://vimeo.com/5206053

and heres a geezer doing a wheelie....down scannupia

gotta have a hobby I suppose

dennisn

bompington wrote:

You don't need much power to go up a 45% gradient - if you can do it slowly. No hard scientific calculations or evidence to offer but I'm fairly sure that traction is the limiting factor in most cases.

Ya, you can climb a wall if you can get traction. Still, you have to keep from falling over if you go really, really slow.

You're right that you MAY not need much power(depending on the vertical feet required) but no matter what the slope the only things that matter(as far as power used or required) is concerned is how much weight(you and the bike) you've got to move and the vertical rise. i.e. if you need to move 200 pounds(you & bike) up, oh say, 1000 vertical feet it will take a certain amount of power / work without reguard to slope angle. How much and how high. Nothing else matters.

ShutUpLegs

joe.90 wrote:

cav probably tweeted that on a wimb and within a day someone has analyzed it to the nth degree!

It's pretty dull tbf fair