Cadence and Mountainbike

[buabco]

HI all!!

I've just bought a heart rate monitor and started looking at possible training programs and it came to me that everybody seems to be recommending hi cadence for biking (90 - 100 rpm)...

So I started surfing the internet and finally came to a formula to calculate cadence with speed and gears... the formula I up with is:

Speed (km/hr) = 0.006 * wheel perimeter (cm) * Cadence (rpm) * Chainwheel cogs / Freewheel cogs

It seems to be right, my problem came when I input into the formula my biggest Chainwheel and my smallest freewheel (44 - 11), if I use a 90 rpm cadence I get 48 km/hr, which is a speed I've never been able to get on a flat surface my bike.

The fastest I've been able to go on a flat surface is about 36 Km/hr (using this gear combination) and this gives me a cadence of about 70 rpm, and even I get tired I can maintain it for a while, my heart rate seems to be going a bit fast (150 bmp).

So mainly my questions are:

1.- Is the formula right?
2.- It seems to me that a 90 or 100 rpm cadence for a mountainbike is too much, which should be a cadence I should target on my training?.

Hope someone can help me with this questions.

Oh by the way, I speak spanish so I'm not sure I used the right words for the bike parts.

 

[triguy98]

try to find the Analytical Cyclist website. all sorts of cool calculataors and such there.

 

[Peka]

That sounds about right for a 44/11 depending on the size of your tyres. 70rpm is getting a bit low.

The fact that it's a MTB makes no difference to the cadence you should be using. My sweet spot for cadence is around 100rpm, though on steep climbs in the dirt it will often drop much lower than that. I wouldn't be pushing top gear at 36kmh, I usually use the 5th or 6th cog (9 speed cassette) and top chain ring (42T).

 

[buabco]

WOW 100??? today I tryed to ride at 70 rpm... well since I didn't have an rpm metter I did 30 Kmph at 44/14

But it really felt link I was spining to fast, my legs got a bit sored also... guess I'll have to get use to hire cadence though (I was doing like 165 bpm).

do you think you nide clips to go over 80?

 

[triguy98]

WOW 100??? today I tryed to ride at 70 rpm... well since I didn't have an rpm metter I did 30 Kmph at 44/14

But it really felt link I was spining to fast, my legs got a bit sored also... guess I'll have to get use to hire cadence though (I was doing like 165 bpm).

do you think you nide clips to go over 80?

Clipless def. helps smooth out the pedaling motion, allowing for a higher cadence. The average MTBer has a cadence of 85, I do about that on the flats, higher when powering up hills and whatnot.

It takes a little getting used to, but you'll find the higher cadence more beneficial to your riding.

 

[cheapie]

and more beneficial to your knees.


i think perhaps your cadence is higher than you think. get on an excercise bike that has a cadence readout and see where you are. 70 and below is quite slow.