EP8 description poser?

[Teriatric]

I'm in the UK. This is a direct quote from the Shimano Steps UK web site where the motors are restricted to 15.7mph/25kph (EP8 e-Bike System – SHIMANO STEPS):

"Responsive, especially noticeable when riding above 25km/h"

How on earth can they claim this? Mine starts to drag you backwards at that speed! Is this just a very bad translation from Japanese or should I try and sue them to get the limit lifted (tongue-in-cheek )

 

[steve_sordy]

They should sack the proof reader.
He/she should have spotted that the 25kph limit for UK sales should have required an edit on that sentence.

 

[Gary]

Mine starts to drag you backwards at that speed! Is this just a very bad translation from Japanese

No.
You're just weak. (and riding a, 25kg lump with big draggy tyres)

The Ep8s resistance above the assistance limit is so slight almost unmeasurable while riding.

 

[Teriatric]

No.
You're just weak. (and riding a, 25kg lump with big draggy tyres)

The Ep8s resistance above the assistance limit is so slight almost unmeasurable while riding.

Too right I'm weak, in the extreme! After riding it on three weekends then jumping on my Trek Fuel for night rides the little 26er thing just flies, so maybe the Merida is making me stronger, I'd like to think so! I had considered saving up for lighter wheels and tyres but I fear the weight of the thing and the bumpy stuff I do would crucify them. What I have found though in its defence is that 15mph is plenty between trees, and I can get it wound up fine with a decent downward gradient regardless of the inherent drag, and I tend to turn it off for flat stuff. Such a shame that OAPs stop producing testosterone so my muscle building days are well gone

 

[Gary]

Smaller volume, Lighter, harder compound faster rolling dry weather treads at higher pressures make a MASSIVE difference to how easy an Eeb is to pedal past the assistance limit.
Eg. Try a set of XC tyres at 40psi.

 

[Teriatric]

@Gary not sure how my vertebrae would cope with over twice the pressure I've used for the last fifteen years! I left Hardtail Heaven behind a very long time ago

 

[Rob Rides EMTB]

Regarding tyre pressures.... I recently read a report suggesting that on any given tyre, a higher pressure is not actually faster rolling. I'll try find it. In the meantime.. here's some stuff I found when I was bored...

Schwalbe statement on tyre pressures and rolling resistance

On a completely smooth surface the following applies: The higher the inflation pressure, the inferior the tire deformation and thus rolling resistance.

Off road it is exactly the reverse: The lower the inflation pressure, the lower the rolling resistance. This applies equally on hard gravel roads and soft forest tracks. Explanation: A tire with low inflation pressure can adapt better to a rugged surface. It sinks into the ground less and the whole rotational mass is held back much less by the uneven surface.

Tires with a smaller diameter have a higher rolling resistance with the same inflation pressure, because tire deformation is proportionally greater. The tire is flattened more and is “less round”.

Wider tires roll better than narrower tires. This statement generally invokes skepticism, nevertheless, with tires at the same pressure a narrower tire deflects more and so deforms more.

Obviously, tire construction also has an effect on rolling resistance. By using less material, less material can be deformed. And the more flexible the material is, such as the rubber compound, the less energy is lost through deformation.

Generally, smooth treads roll better than coarse treads. Tall lugs and wide gaps usually have a detrimental effect on rolling resistance.

Why do wide tires roll better than narrower tires?

The answer to this question lies in tire deflection. Each tire is flattened a little under load. This creates a flat contact area.
At the same inflation pressure, a wide and a narrow tire have the same contact area. A wide tire is flattened over its width whereas a narrow tire has a slimmer but longer contact area.

The flattened area can be considered detrimental to tire rotation. Because of the longer flattened area of the narrow tire, the wheel loses more of its “roundness” and produces more deformation during the rotation. In a wide tire, the flattened area is shorter in length and does not have so much effect on the rolling direction. The tire stays “rounder” and therefore it rolls better.

Also found this study interesting (more road oriented, but worth a browse):

Myths Debunked: Higher Tire Pressure is NOT Faster

This used to be one of the first things you learned as a cyclist: If you want to go fast, make sure your tires are pumped up to the maximum pressure. The harder your tires are inflated, the faster they roll. We now know that…

www.renehersecycles.com

 

[Gary]

Rob.
1. Ride a normal bike
2 Try sprinting with 20psi f&r
3 try sprinting with 40PSI f&r

Now tell me which pressure rolled faster.

You'll find the same resulting decrease in pedalling effort required with (most) climbing and most fire road traversing and most groomed flow trails.

Yes lower pressures roll faster the rougher the trail. Especially when you're not pedalling or pumping the terrain.

Most folk moaning about their Ebike being hard to pedal over 25kph aren't trying to pedal while riding anything genuinely very rough above 25kph.

Oh... And Schwalbe can feck off with their stupid comparisons of LARGER volume tyres at the SAME pressures as smaller volume tyres.