Neo 2T - cranks too short for cadence?

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Legs

usually riding on Zwift...
Location
Staffordshire
A bit of a funny one, so bear with me.

My 7yo has taken to riding Zwift on his mountain bike on my Neo2T (he started last week and has ridden about 90 miles!). Unfortunately, because of the long chainstays and short cranks, the cadence sensor doesn't reliably detect his feet passing, so we get a display of 63-65rpm on the screen, irrespective of how fast his little legs are going round! When going uphill (anything >5%), he bogs down, the cadence display drops off, and he finds it almost impossible to get going.

What I want to know is; is this a problem? Is the software adjusting his resistance on the basis of this spurious cadence? Or is it all catered for in the internal workings of the machine? I can't really gauge whether the resistance is realistic because my big feet trigger the sensors, and Andrew doesn't really know what feels right and what feels wrong. I suppose we should try with Trainer Difficulty turned down a bit?

I know there are workarounds, such as zip-tying a spanner to the crank... or getting a separate BLE cadence sensor... but do we actually need to do either of these?
 

bobinski

Legendary Member
Location
Tulse Hill
A bit of a funny one, so bear with me.

My 7yo has taken to riding Zwift on his mountain bike on my Neo2T (he started last week and has ridden about 90 miles!). Unfortunately, because of the long chainstays and short cranks, the cadence sensor doesn't reliably detect his feet passing, so we get a display of 63-65rpm on the screen, irrespective of how fast his little legs are going round! When going uphill (anything >5%), he bogs down, the cadence display drops off, and he finds it almost impossible to get going.

What I want to know is; is this a problem? Is the software adjusting his resistance on the basis of this spurious cadence? Or is it all catered for in the internal workings of the machine? I can't really gauge whether the resistance is realistic because my big feet trigger the sensors, and Andrew doesn't really know what feels right and what feels wrong. I suppose we should try with Trainer Difficulty turned down a bit?

I know there are workarounds, such as zip-tying a spanner to the crank... or getting a separate BLE cadence sensor... but do we actually need to do either of these?

I have read elsewhere it makes no difference to resistance.
 

Bobario

Veteran
Your cadence doesn't alter the resistance in the trainer, but a low cadence makes it harder to spin the cranks when the resistance does ramp up. Lowering the difficulty level would definitely help, as it would effectively give him a lower gear.
 

T.M.H.N.E.T

Rainbows aren't just for world champions
Location
Northern Ireland
Lack of cadence will only bog the trainer down in erg mode during a workout (presumably he isn't doing)

Garmin/Tacx own solutions aren't great https://support.garmin.com/en-GB/?faq=btBijKpQyY6MQ11TybJVE9
 
Shorter cranks gives you a smaller mechanical advantage so it's harder to push the pedal down any one gear.
But shorter cranks also means that your feet don't move as fast in the same gear.
Combine the two effects and it's easier to ride in that gear with a higher cadence vs the cadence you'd want with longer cranks.
It's fairly standard to have shorter cranks on a recumbent where it's helpful to ride with a high cadence.

The workaround for a young rider is just to lower the resistance to match the lower mechanical advantage.

Luck .............. ^_^
 
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