Answered Why is it believed that speed derestriction damages the motor?

[GrahamPaul]

I see quite lot of comments on here from folk saying that they will not be derestricting their bikes because it "will damage the motors".

Given that EMTB's are pedelecs, with the motor assisting the pedals, it seems to me that the limiting feature on motor assistance is how fast the pedals are being turned.

My little legs will only pedal at around 120rpm for a very few seconds. Even 110rpm is painful other than for a very short time.

The speed of my puny legs can be 110rpm in a 50 tooth cog or a 10 tooth cog - the speed down the road is a factor of 10 different. Thus the speed of the bike is entirely dependent on the size of that rear cog (for a given front sprocket and rear tyre).

The top speed of the bike is constrained by how fast my legs will turn in the top gear. But, given that my legs could equally be spinning at that same manic rate in a low gear up a steep climb, where is the damage caused by only the same motor output at the same rotational speed just because the velocity is greater?

(I have a, perhaps misguided, belief that motor manufacturers are making it as difficult and painful to derestrict their motors because they are worried about litigation arising from death/accidents caused by speed on derestricted bikes.)

 

[Jamsxr]

Raising it to the US limit isn’t exactly de-restricting the bike, we’re just rebelling against our EU overlords ?

Frankly the EU limit was limiting the fun factor of the bike, I’m regularly pedalling above 15mph as trails and jump lines in the UK frequently demand that. However, pedalling a 22kg bike was helping keep me fit!

I still ride my MTB most of the time, and personally I wouldn’t bother with an eBike at all unless I knew I could override the EU limit.

 

[GrahamPaul]

Raising it to the US limit isn’t exactly de-restricting the bike, we’re just rebelling against our EU overlords ?

Frankly the EU limit was limiting the fun factor of the bike....

Forgive me if I'm wrong, but doesn't the EU speed limit (for which you can have electric support power) apply to roads/public highways/public cycle paths?

Off-road, you are free to ride at whatever speed you want? Come to that, you are free to ride at whatever speed you like - just without the assistance of the electric motor. (Except here in Spain, where bicycles, of whatever type, have a mandatory speed limit on the public highway of 40kph).

I can see the sense in this because it's not just EMTBs that are limited but all Ebikes. Can you imagine the carnage in Amsterdam or Munich where clowns would be riding at 25mph on the crowded city centre cycle paths during prime school run and commuting time? (And yes, I do realise that they can ride clockwork bikes at those speeds - but not for far before they are too sweaty for the office - or get caught by other commuters and have the crap beaten out of them).

Having lived in a number of German and Dutch cities over a good few years, I really can see the reason for the speed limit. There are vastly more "normal" Ebikes on the road than there are EMTBs. We're just caught up in the desire to constrain the nutters running over school kids. (A mate of mine got his shoulder broken by a speeding clockwork bike as he was getting off a tram. Bikes can hurt third parties badly.)

Bicycle commuter usage is much different in the US - as is the city cycle path network - so, again, I can see the sense of 25mph.

Rail against the laws as much as you like - I love the German autobahns with their speed limit set to the speed of light - but you always find that you are going to be punished for life's arseholes. Thus, in the not too distant future (2022), all new EU cars will be fitted with speed limiters to ensure compliance with road speed limits. Just as all German autobahns will soon be losing their unrestricted status.

No motor manufacturer (European ones, anyway) wants to leave themself open to charges of negligence - and I am pretty sure this is why the anti-tamper measures. Yes, our EMTBs might be able to go a bit quicker on the single track (highly debatable in this part of the world) and we are being unfairly swept up into the restrictions needed to make our overcrowded cities work more peacefully. If you don't like it, derestrict your motor but stay off the public highway.

All of which brings me back to my original thesis: restricting motors to a set speed limit is not to protect the motor and that removing that restriction will not damage the motor given that its power output is restricted.

 

[Zimmerframe]

Forgive me if I'm wrong, but doesn't the EU speed limit (for which you can have electric support power) apply to roads/public highways/public cycle paths?

Off-road, you are free to ride at whatever speed you want?

Almost, except I think you're only allowed to ride "unrestricted" on "Private" land, not public land. A lot of the forests and other places people ride will be public, not private. Some of these might be privately/corporately owned but have areas open for public access, which I'm guessing would fall under the classification of public areas and therefore require you to abide by the laws.

So for me, with 4000 hectares of "private" forest on my doorstep, I should in theory be able to ride unrestricted. But if I crossed into the public area, I'd have to reset the bike to restricted to remain legal.

 

[Mikerb]

The rating of an electric motor is not an expression of power. It merely describes the electrical limits within which it is designed to operate...e.g input voltage. The best description of motor output is the stated torque although none of the motor manufacturers seem to specify where that is measured. If you mess with the motors inputs..e.g. voltage then you will shorten the life of the motor. Other than that you cannot alter the amount of power delivered. The controlling software merely controls the current delivered ,within the motors electrical specification, using sensors to measure rider torque input and cadence and the bikes speed. ....as measured by the rotation of the back wheel. Altering the top assisted speed will make no difference to the motor other than the potential for the motor to be in operation marginally more. I would guess that eventually manufacturers will either add another device to cross check speed...possibly a gps chip....or replace the existing speed sensor with an alternative method.
In terms of legality a deristricted bike should conform to laws governing motorbikes if on a public highway. Those laws do not apply when not on a public highway but (in the UK) there are a range of other laws which can be applied most specifically if an accident occurs involving an illegal vehicle.....public or private land would make no difference, albeit there maybe additional liability if motor vehicles are banned on public access land (as is usually the case).

 

[Jamsxr]

Forgive me if I'm wrong, but doesn't the EU speed limit (for which you can have electric support power) apply to roads/public highways/public cycle paths?

Off-road, you are free to ride at whatever speed you want? Come to that, you are free to ride at whatever speed you like - just without the assistance of the electric motor. (Except here in Spain, where bicycles, of whatever type, have a mandatory speed limit on the public highway of 40kph).

I can see the sense in this because it's not just EMTBs that are limited but all Ebikes. Can you imagine the carnage in Amsterdam or Munich where clowns would be riding at 25mph on the crowded city centre cycle paths during prime school run and commuting time? (And yes, I do realise that they can ride clockwork bikes at those speeds - but not for far before they are too sweaty for the office - or get caught by other commuters and have the crap beaten out of them).

Having lived in a number of German and Dutch cities over a good few years, I really can see the reason for the speed limit. There are vastly more "normal" Ebikes on the road than there are EMTBs. We're just caught up in the desire to constrain the nutters running over school kids. (A mate of mine got his shoulder broken by a speeding clockwork bike as he was getting off a tram. Bikes can hurt third parties badly.)

Bicycle commuter usage is much different in the US - as is the city cycle path network - so, again, I can see the sense of 25mph.

Rail against the laws as much as you like - I love the German autobahns with their speed limit set to the speed of light - but you always find that you are going to be punished for life's arseholes. Thus, in the not too distant future (2022), all new EU cars will be fitted with speed limiters to ensure compliance with road speed limits. Just as all German autobahns will soon be losing their unrestricted status.

No motor manufacturer (European ones, anyway) wants to leave themself open to charges of negligence - and I am pretty sure this is why the anti-tamper measures. Yes, our EMTBs might be able to go a bit quicker on the single track (highly debatable in this part of the world) and we are being unfairly swept up into the restrictions needed to make our overcrowded cities work more peacefully. If you don't like it, derestrict your motor but stay off the public highway.

All of which brings me back to my original thesis: restricting motors to a set speed limit is not to protect the motor and that removing that restriction will not damage the motor given that its power output is restricted.

The US limit is 20mph so we’re all good, safety first ?

Personally I think, in the UK at least, if we want to get more people traveling on bikes raising the limit should help promote that. When I used to commute my average speed was always over 15mph, so to me, 20mph makes sense. It gets me to my destination quicker and I’ll be less of a sweaty mess.

To be fair, our EU overlords and the current restrictions don’t bother me much, provided there’s a sneaky way around them if you go looking.

 

[R120]

If you ride a normal ebike, one designed for commuting, the cut off of assistance is no where near as noticeable or annoying - we have two Bosch motored Bergamont hybrids in my family, and riding them is a very different experience to riding an emtb - they are much more resolved riding experiences, and work very well, but the main reason is that they weigh a lot less, and run nice slick commuting tyres, meaning the cut off isn't anything like as much of, if at all, an issue.

The also both run Alfine DI2 hub gears, which integrate with the Bosch system, and really are bikes you can just hop on and ride, let the motor do its thing - in fact I dont think I have ever really though about the cut off being an issue when riding them.

With an EMTB the riding experience between assistance and non assistance is far more pronounced, because the weight, draggy tyres, suspension platform etc are no longer being "compensated" for by the motor.

 

[GrandPaBrogan]

I think it would be fair to say that 'speed de-restriction' in itself will not damage the motor if the parameters are within what the motors have been designed for. Unsanctioned tampering or DIY hacking of any kind of sophisticated electronic system on the other hand creates unpredictable consequences. It is understandable that this would therefore void the manufacturer's warranty, considering the complexity of today's pedal-assist motor designs. I can also appreciate why newer eBikes have tamper-proof countermeasures built in.

Think about... [weight / durability / power output / cadence input / bike speed / heat / battery discharge rate / production cost]... just to name a few.

Any initiative to optimise any one of these items in the design development phase will have an adverse effect on the other parameters. And because we consumers want to have our cake and eat it too, engineering teams spend countless hours squeezing blood out of these stones - to find some kind of ideal balance that might maximise each parameter without creating unacceptable compromises. The lighter, more powerful, longer-lasting an eBike system is made to be... the more these aspects will interact in a knife edge balance. We shall have our cake, but there's no such thing as a free lunch. The authors of this engineering work of art therefore, are the ones qualified to specify where and how much change in their system can be tolerated without causing damage. No doubt there are also other brilliant people out there that have the capability interpret the proprietary architecture correctly and modify motors within safe limits.

Government legislation as to what speeds the assist-limits should be - is another matter.

The impact that derestricted eBikes might have on land access when legislations are deliberately ignored - is also another matter.

 

[Rusty]

If you ride a normal ebike, one designed for commuting, the cut off of assistance is no where near as noticeable or annoying - we have two Bosch motored Bergamont hybrids in my family, and riding them is a very different experience to riding an emtb - they are much more resolved riding experiences, and work very well, but the main reason is that they weigh a lot less, and run nice slick commuting tyres, meaning the cut off isn't anything like as much of, if at all, an issue.

The Brose is terrible at the cut-off. Starts to drag early and is like an anchor out when it hits 32kph. With the Shimano I could pedal through and still get a little more speed.
Waiting for the new Scott Genius eRide with the Bosch to take for a decent spin as my only test was in a small car-park where I could not get 32kph easily.

 

[wepn]

The Brose is terrible at the cut-off. Starts to drag early and is like an anchor out when it hits 32kph. With the Shimano I could pedal through and still get a little more speed.
Waiting for the new Scott Genius eRide with the Bosch to take for a decent spin as my only test was in a small car-park where I could not get 32kph easily.

Interesting! Have you tried BLEvo? In Smart Power - Expert mode - there's an option called Delay Decreasing Assistance. Worthwhile trying. Just don't tell anyone you're using AUTO VerySoft

It has two functions.
a. Determines the responsiveness once the threshold has been reached.
b. Specifies the percent decrease once the Smart threshold has been reached.
There are two types of options you can choose from, the older manual percentage-based decreases with a fixed response delay, or an AUTO option which calculates both decrease amount and response delay. There are four AUTO options to choose from:
c. AUTO SuperEco: assistance is quickly decreased. This is the most economical setting but the harshest on your legs.
d. AUTO Eco: assistance is rapidly reduced.
e. AUTO Soft: assistance is reduced more slowly.
f. AUTO VerySoft: assistance is reduced even more slowly.

 

[Roberto6170]

I've had a Bosch activeline on an MTB with a speedsensor derestrictor on it and used it for a number of years in Spain with absolutely no probs at all apart from the Speedo displaying nonsense speeds! No overheating or strange noises just much better to use

 

[Waynemarlow]

Guys you can ride a speed derestricted bike on public roads without a problem, just don't go over 15mph in the EU. Simple. On Private land you can go at whatever speed you want.

But don't think you can put a 2000W motor on and not break the law, the 250W law is tenuous but all encompassing if you don't have a manufacturers sticker on stating 250W's

 

[Mikerb]

Guys you can ride a speed derestricted bike on public roads without a problem, just don't go over 15mph in the EU. Simple. On Private land you can go at whatever speed you want.

But don't think you can put a 2000W motor on and not break the law, the 250W law is tenuous but all encompassing if you don't have a manufacturers sticker on stating 250W's

...that is poor advice Im afraid. Both in the EU and the UK the definition of a pedelec is very clear and it has nothing to do with how fast you ride, and everything to do with the specification of the bike you are riding. Part of that specification is that the motor provides no assistance over 15.5 mph or 20 mph in the US etc). Any ebike that does not conform to the pedelec specifications ceases to be a pedelec and the defining aspect of a pedelec is that it is treated in law and for access as a bicycle.

There is the S Pedelec classification which provides greater speeds and it is treated somewhat differently even within different EU member states but in the UK it is treated in law the same as a moped except that it also requires individual type approval. So, DVLC registration, insurance, moped licence, helmet, lights etc.

You can, as you say, ride a bike powered by an electric motor that does not conform to the pedelec regulations on private land with permission of the land owner. That private land must however provide/contain no public access and in all probability from a legal point of view be able to demonstrate that measures have been taken to prevent any unauthorised access.

 

[Alexbn921]

Guys you can ride a speed derestricted bike on public roads without a problem, just don't go over 15mph in the EU. Simple. On Private land you can go at whatever speed you want.

But don't think you can put a 2000W motor on and not break the law, the 250W law is tenuous but all encompassing if you don't have a manufacturers sticker on stating 250W's

I can ride my road bike 25mph on flat ground. I'm dangerous.

 

[Alexbn921]

Road Bike

MTB bike no motor