# General Cycling Discussion - Some help with a technical cycling term, please!

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mooklekloon
07-10-07, 08:16 AM
Hi everyone,

I know that cadence is the actual rotational speed of the cranks measured in RPM.

However, I was wondering if there was a term to describe a similar but related concept. For each speed of the wheel, and each gear, there is minimum cadence that is required in order to engage the cranks (the minimum cadence so that you are not free pedaling). Is there a technical term cyclists use to describe this specific value?

Bob Ross
07-10-07, 08:58 AM
"Threshold Of Motation"

Cyclaholic
07-10-07, 07:24 PM
Rotational event horizon?

thequickfix
07-10-07, 09:01 PM
I don't think that there is a different term for what you are describing, because it is effectively the same as cadence.

Thinking as I type here...
For a given speed (m/s) (v=s/t), the wheel rotates at a certain rate (vr=(2pi(s/2.02))/t) (i.e., angular rotation of the wheel per second, assuming 700x23 tires). The rotational velocity of the wheel is directly related to the minimum rpms of the crank by the gear ratio (chainring/cog). So, in order to find the necessary angular rotation of the crank per second you would simply multiply by the reciprocal ((cog/chainring)*(2pi(s/2.02))/t).

All of this calculates the minimum cadence for a given velocity and gear ratio, but it is also a backwards way of describing how cadence and gear ratio determine velocity. In other words, given any two of the three variables, the other necessarily follows.

DannoXYZ
07-11-07, 07:04 AM
I know that cadence is the actual rotational speed of the cranks measured in RPM.

However, I was wondering if there was a term to describe a similar but related concept. For each speed of the wheel, and each gear, there is minimum cadence that is required in order to engage the cranks (the minimum cadence so that you are not free pedaling). Is there a technical term cyclists use to describe this specific value? Same thing as cadence. Spinning slower than the current cadence to maintain that speed in that gear is called "soft pedaling" where you're not really applying much force at all. This is a way to slowly adjust speed in a pack without making drastic actions like braking and messing up the guy behind you.

Bob Ross
07-11-07, 07:34 AM

He wants to know if there's a name for the cadence threshold for any given gear-inch combination beneath which the rider is soft-pedaling, and above which the pawls on the rear hub are engaged by the drivetrain.

I'm pretty sure the correct answer is "no, there isn't a name for it."

Cyclaholic
07-11-07, 07:58 AM
It depends where you're from, on the east coast it's called "the cadence below which you're soft pedalling", however on the west coast it's called "the cadence above which you're not soft pedalling"

....can be confusing.

thequickfix
07-11-07, 04:09 PM

He wants to know if there's a name for the cadence threshold for any given gear-inch combination beneath which the rider is soft-pedaling, and above which the pawls on the rear hub are engaged by the drivetrain.

I'm pretty sure the correct answer is "no, there isn't a name for it."

Actually, I'm almost certain it's the same thing. Think about it: for a given speed and gear ratio, the rate of rotation of the cranks necessarily follows, regardless of whether you are "soft pedaling" or not. Consider a fixed gear drivetrain. Even if you are not applying pressure to the pedals, the cranks will spin at a certain rate depending upon how fast you are going.

caloso
07-11-07, 04:19 PM
Paul Sherwen calls soft pedaling "glass cranking." Therefore the term you are searching for is "anti-glass cranking."

DannoXYZ
07-11-07, 05:08 PM
Actually, I'm almost certain it's the same thing. Think about it: for a given speed and gear ratio, the rate of rotation of the cranks necessarily follows, regardless of whether you are "soft pedaling" or not. Consider a fixed gear drivetrain. Even if you are not applying pressure to the pedals, the cranks will spin at a certain rate depending upon how fast you are going.Yeah huh?
"there is minimum cadence that is required in order to engage the cranks (the minimum cadence so that you are not free pedaling)."Sounds a lot like just pedaling cadence. Now there may be a difference between FORCE on the pedals. If you pedal with more force than necessary to maintain steady-speed, you'll accelerate. If you with exactly the required amount of force to overcome air-drag and rolling-resistance, you'll maintain steady-speed. Even when you're initially soft-pedaling with less force than required, you're STILL at that same cadence.

Then anything slower than normal cadence is really the same as coasting. There's not enough force to maintain steady speed. It's actually possible with soft-pedaling to pedal slower than necessary, but still have the crank & rear-hub pawls engaged with barely any force.

Retro Grouch
07-11-07, 05:30 PM
I don't know the answer but I'm curious. Why do you ask?

Tom Stormcrowe
07-11-07, 05:40 PM
Circulation maintenance of the legs while coasting?

That would be my proposal. On long coasts down hill, I will slowly roll the cranks to keep the blood flow going in my legs. Is that what the OP is asking?

nox tuboid
07-11-07, 09:09 PM
How this information could posibly be of any use to any one is beyond me but what the hey....

cooker
07-11-07, 09:16 PM

He wants to know if there's a name for the cadence threshold for any given gear-inch combination beneath which the rider is soft-pedaling, and above which the pawls on the rear hub are engaged by the drivetrain.

I'm pretty sure the correct answer is "no, there isn't a name for it."
No, the correct answer is, there is no such thing. If you slowly braked to a stop while pedalling firmly in any gear, your cadence would gradually drop to zero but the gear would remain engaged. There is no point where you drop below a threshold for that gear.

If you want to calculate the cadence for a particular gear combo and speed you can, but it is a predetermined number...there is no variability in it.

If you are riding at a speed that means your wheel is spinning at 100 rpm and you are in a 48/24 combo (if there is such a thing), the pedals must be spinning at 50 rpm. Anything less than that and you are coasting; anything more, and you have sped up the bike.

edp773
07-11-07, 10:18 PM
Pedaling as opposed to not pedaling. There is no term cyclists use, but maybe a bicycle engineer has a term.

cooker
07-12-07, 07:48 AM
Just to recap my longer post, you're either pedalling at the cadence that matches your gears and speed, or you're not.

caloso
07-12-07, 10:37 AM

timmhaan
07-12-07, 10:42 AM
yeah, the cadence will be a fixed value depending on speed\gear.

are you asking if there is a term for pedaling below that cadence?

Bikepacker67
07-12-07, 10:54 AM
He wants to know if there's a name for the cadence threshold for any given gear-inch combination beneath which the rider is soft-pedaling, and above which the pawls on the rear hub are engaged by the drivetrain.

I'm pretty sure the correct answer is "no, there isn't a name for it."

Isn't this dependent upon speed?
At 3mph, a 34X17 gear combo can be engaged with a low cadence.

Treker
07-12-07, 11:39 AM
It depends where you're from, on the east coast it's called "the cadence below which you're soft pedalling", however on the west coast it's called "the cadence above which you're not soft pedalling"

....can be confusing.

And if we consider whether we're in the northern or southern hemisphere, well then, the situation becomes quite complex indeed. :)