Suspenion and speed

[tenderbehind]

I vaguely remember reading the other day that suspension setting and pre load setting can affect the speed of an e bike, or perhaps any ordinary bikes, I can't see how or why it should, can anyone enlighten me please?

 

[iaing]

I vaguely remember reading the other day that suspension setting and pre load setting can affect the speed of an e bike, or perhaps any ordinary bikes, I can't see how or why it should, can anyone enlighten me please?

As I understand it, the theory is that the suspension absorbs some of the rider's energy on pedalling. No idea if it is actually true though.

Iain

 

[flecc]

It can be true and often is on bikes with their generally poor suspension damping standards.

Movement upwards of the sprung assembly absorbs energy, and if poor damping permits the sprung assembly to overbounce upwards and then rebound, the force impacts back to the road. With the forks sloped forwards and the wheel speed mismatching the road surface due to the bounce, the rebound force slows the forward motion.

With regard to the effect on pedalling, the suspension compression as it acts stores the energy momentarily in it's springs as referred to above. Half of that rebound energy is returned to the road, the other half up into the bike. With soft and poorly damped suspension the upward movement of the bike can be greater than if the bike had no suspension. Since this will often be out of synchronism with the rider actions, it often opposes the rider pedal strokes and upsets muscle rhythm.

And of course the main loss of pedal effort with soft suspension is the way in which it gives under hard pedalling downstrokes, transferring the forces intended for propulsion into storage in the springs for the later disturbing return referred to. This is worse with rear suspension, though well designed geometry can alleviate the effects to some extent.

The degree of the suspension effects on pedalling with e-bikes is set by the proportion of rider effort contributed, in turn affected by the available motor power, but the ill effects are never as severe as they are with unpowered bikes.
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[SEATALTEA]

The bulk of bikes under a few hundred £££s have cheap suspension which is often little more than a basic spring fitted inside only one of the front forks or somewhere under the rider if it has 'full suspension'. Travel on the flat and other than the slight weight gain they bring nothing more than a more comfortable ride.

When you begin to climb, descend or travel on anything other than a flat surface a % of the input from the rider or the terrain is absorbed by the suspension. So if your pedal input whilst climbing is 100% then front and rear springs may steal a combined 10% of the energy you put into the bike just going up and down with each pedal stroke.

Pay a little more and you can get suspension with a multitude of adjustments for your riding style, terrain, weight etc which is of great use when riding up or down hills like this on a MTB http://www.panoramio.com/photos/original/5598004.jpg

On electric bikes designed for road use I fail to see the point of suspension, rider comfort could be addressed with a sprung seat post.

 

[keithhazel]

It can be true and often is on bikes with their generally poor suspension damping standards.

Movement upwards of the sprung assembly absorbs energy, and if poor damping permits the sprung assembly to overbounce upwards and then rebound, the force impacts back to the road. With the forks sloped forwards and the wheel speed mismatching the road surface due to the bounce, the rebound force slows the forward motion.

With regard to the effect on pedalling, the suspension compression as it acts stores the energy momentarily in it's springs as referred to above. Half of that rebound energy is returned to the road, the other half up into the bike. With soft and poorly damped suspension the upward movement of the bike can be greater than if the bike had no suspension. Since this will often be out of synchronism with the rider actions, it often opposes the rider pedal strokes and upsets muscle rhythm.

And of course the main loss of pedal effort with soft suspension is the way in which it gives under hard pedalling downstrokes, transferring the forces intended for propulsion into storage in the springs for the later disturbing return referred to. This is worse with rear suspension, though well designed geometry can alleviate the effects to some extent.

The degree of the suspension effects on pedalling with e-bikes is set by the proportion of rider effort contributed, in turn affected by the available motor power, but the ill effects are never as severe as they are with unpowered bikes.
.

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parts of this i can vouch for(the other parts are too technical for me ) as one of my previous bikes was a SYNERGY going under the name of a EDISON...plus other names which i forget,this was a very good bike in lots of ways,under geared for pedaling above 12mph and underpowered as was a 24 volt was the reason i got rid of it, but it was the most comfortable ride i have had,i never felt a bump at all as suspension was like one of them baby bouncer things,so for pottering around it was a superb ride,but anytime you tried to push the pace your imput was battling against the suspension and not all going where it should on the pedals...if i only ever wanted a bike to go at 10mph like on a sunday stroll i would never have got rid as it was excellant....horses for courses...

 

[flecc]

http://www.panoramio.com/photos/original/5598004.jpg

On electric bikes designed for road use I fail to see the point of suspension, rider comfort could be addressed with a sprung seat post.

There are a few circumstances where sprung forks can be a benefit on an e-bike, and I've covered those on my suspension article in the technical section.
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[joab]

In short suspension adds confort but you lose some speed.

 

[Caph]

In short suspension adds confort but you lose some speed.

I've always felt that electric bikes are ideal for suspension since it's the battery doing the work, and if it has to work a bit harder for my ride to be comfier then that's fine by me. I have to say that my suspension is quite stiff so I mainly benefit from it off road but some of the roads near me almost qualify as off-road!