Calculating power required to ascend a gradient

jibberjim

Stephencp wrote:

Jibbering Jim - could you expand on your earlier comment about the the different inertial loading between hill climbing and riding on the flat and perhaps explain what effect this has on the rider.

To put it very simply, when you have high inertia - your bike is going fast, your wheels are spinning fast and with the gearing it's "helping" the pedals turn through the parts where you don't normally push down. When the inertia is lower, because you're not going fast (and a really grinding gear changes the inertia seen at the pedal too) then you don't get this help turning the pedals.

The result is that it feels very different to your legs - and IIRC the studies show you actually recruit different muscles in the different situations, it certainly changes the cadences you choose.

Stephencp

Thanks for that Jim, I`d certainly agree it feels different.

thecrofter

Pokerface wrote:

amaferanga wrote:

Pokerface wrote:

But there are no hills in the UK that take an hour to get up! Longest one is all of about 20 minutes!

(But if not in the UK - I agree with you. It's easier to do higher wattages for longer times when on an incline.)

If you can get up the Bealach na Ba and Dufton Fell in 20 minutes then I suggest you give team Sky a call

The longest continuous climb in the UK is only about 5 miles long. Thus about 20 minutes of riding.


However - I was being technical about it and I'm sure there are longer 'climbs'. Just with little breaks in them.

The Bealach is 6 miles and rises over 2000ft from the moment you join the road at Tornapress until the summit there is no respite, it is continuous!!(check the Guiness book of Records - Longest Steep Hill in Britain, if you don't believe me). Given it's all very single track it takes nearly twenty minutes to drive up it in a car, but if you reckon you could manage it in twenty minutes on your bike, off you go.

SteveR_100Milers

jibberjim wrote:

Stephencp wrote:

Jibbering Jim - could you expand on your earlier comment about the the different inertial loading between hill climbing and riding on the flat and perhaps explain what effect this has on the rider.

To put it very simply, when you have high inertia - your bike is going fast, your wheels are spinning fast and with the gearing it's "helping" the pedals turn through the parts where you don't normally push down. When the inertia is lower, because you're not going fast (and a really grinding gear changes the inertia seen at the pedal too) then you don't get this help turning the pedals.

The result is that it feels very different to your legs - and IIRC the studies show you actually recruit different muscles in the different situations, it certainly changes the cadences you choose.

Which is also why riding a turbo at the same cadence and power as on the road feels very different, and therefore unholy.

DaveyL

thecrofter wrote:

The Bealach is 6 miles and rises over 2000ft from the moment you join the road at Tornapress until the summit there is no respite, it is continuous!!(check the Guiness book of Records - Longest Steep Hill in Britain, if you don't believe me). Given it's all very single track it takes nearly twenty minutes to drive up it in a car, but if you reckon you could manage it in twenty minutes on your bike, off you go.

Yeah, I believe the fastest guys in the Bealach sportive do it in about 40 minutes, but it is very much dependent on which way the wind is blowing...

amaferanga

2009 Bealach was a very, very windy one. Fastest for those that dibbed was 39:03 (over 5 mins quicker than me )

thecrofter

amaferanga wrote:

2009 Bealach was a very, very windy one. Fastest for those that dibbed was 39:03 (over 5 mins quicker than me )

I'm hoping for a south-westerly no more than about 10mph, the last time I cycled up the Bealach was thirty years ago, so I'm hoping it'll be gentle with me.

DaveyL

amaferanga wrote:

2009 Bealach was a very, very windy one. Fastest for those that dibbed was 39:03 (over 5 mins quicker than me )

Yeah, I did the first one, back in 2006, was it? I seem to remember it was a pretty calm day, maybe even a slight tailwind on the climb, and I think the top guys were closer to 30 than 40 min that day.

Paid for it with a headwind on the last bit from Torridon to Kinlochewe though