Review What is your hub 'freewheel' time? Rolling resistance comparison

[Carbon.]

I am only familiar with the mxus and bafang, but with them, the clutch is between the planetary gear triangular body/carrier and the axle. During motor freewheeling (unpowered) , the motor pinion is stationary, the whole triangular planetary gear body which is normally locked to the axle now spins and the planetary gears must also spin (load-less) as they are between the stationary motor pinion (sun gear) and the moving outer ring gear on the hub.

Which Bafang model have you used?
I consider buying Bafang rear model but their availability is really poor.

 

[Deleted member 16246]

Ah....But you need to compare 'like with like' as regards the weight/size of the tyre and rim. A hub fitted with a large and heavy 29"tyre will have a greater 'flywheel effect' than a smaller lightweigh 16" wheel on a Brampton, so should spin for longer.

Yes - but another important variable is the force applied to spinning the wheel in the first place.

 

[Carbon.]

Yes - but another important variable is the force applied to spinning the wheel in the first place.

Yes, and the higher inner rolling resistance in a hub the quicker it stops.

 

[Sturmey]

We talking about very low levels of energy here, even in the worst case. The kinetic energy (momentum) in the wheel will be about 50 joules and in Carbon's bike, it depletes over 19 seconds. The energy loss in this example is about 2.5 joules/sec or 2.5 watts. However this loss takes place over a variable reducing speed range and I would double this figure to 5 watts in the case of someone having to make a one hour cycle home at 25km/hr with no battery or power. The average cyclist in this case would need a leg output of perhaps 200watts so adding the front hub unpowered represents a 2.5% loss of pedal power.

Flywheels - Kinetic Energy

The kinetic energy stored in flywheels - the moment of inertia.

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