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Unanswered UK vs US Bosch CX motor performance

Long Way Home

New Member
Jun 9, 2022
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Cornwall
I have just joined the forum and am new to ebikes in general, in fact, my bike is yet to arrive, but I have a question regarding the performance difference between the US and UK/EU versions of essentially the same bike and that is...

What is it that actually limits the UK/EU bikes to 15.5mpg that allows some US bikes to 20mph? Is it a software region lock or is it in the speed sensor hardware?

My Trek Powerfly is going to be a commuter, but I'm concerned that the paltry limit of 15.5mph is going to be more of a nuisance than help, as I am likely to be riding at or just above this when cruising. Most regular riders of non assisted pedal bikes, will be quite capable of cruising at well in excess of the UK limitations and the cut off could well make the commute a pain and I'm trying to avoid using the car whenever possible.

Raising the limit to the US 20mph would actually have a large impact on my commute time and fatigue levels, making the commute enjoyable, rather than a grind.
 

Doomanic

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It's a software setting which cannot be changed internally, you have to use an external "cheat" device like a Volspeed V3 or 4.

Raising the assist cut-off over 15.5mph essentially makes the bike a speed pedalec with all the ball-ache that entails; registration, insurance, approved helmet. Whether it has any risk in the real world is for you to decide although I'm sure there will folks along soon to tell you they've been riding bikes that'll 50 for years and never been caught.
 

Long Way Home

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Jun 9, 2022
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If it truly is a software setting, then it can be changed, as the bike is designed for a higher speed. The next question is, how? I suspect that the solution is simpler than a chip,.
 

Long Way Home

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Jun 9, 2022
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i have had a dongle on my bike for 8 years now plod is not interested but it will half the range of the batt if you ride it going 30mph.
I would try to keep the bike within the original design remit for reasons of longevity, it's really about raising the ceiling for the motor on/off sequence at cruise.
 

Long Way Home

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Jun 9, 2022
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bosch use can bus programming it has not been hacked on the controller side and bosch dealers can not chage the region locks so only option is a dongle to remove the speed limit.

i use a bad ass dongle that slides over the speed sensor so can be removed in seconds but only shows half speed on the display
That dongle looks like the perfect thing for the job. Is it tuneable? Can it be set up to limit to say, 20mph?
 

Doomanic

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If it truly is a software setting, then it can be changed, as the bike is designed for a higher speed. The next question is, how? I suspect that the solution is simpler than a chip,.
It's not. The software to access the system is proprietary and region locked. That is to say a UK shop cannot access the US severs and vice versa.
And what could be simpler than pugging in a dongle and riding off into the sunset at Mach 5?
 

Doomanic

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@soundwave, your bike is Gen 2, right? The Gen 4 is much more sophisticated in it's tamper detection. The Volspeed V3 and V4 have user adjustable limit and can be used without detection as long as you don't go silly with the top speed.
 

Mikerb

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It's a software setting which cannot be changed internally, you have to use an external "cheat" device like a Volspeed V3 or 4.

Raising the assist cut-off over 15.5mph essentially makes the bike a speed pedalec with all the ball-ache that entails; registration, insurance, approved helmet. Whether it has any risk in the real world is for you to decide although I'm sure there will folks along soon to tell you they've been riding bikes that'll 50 for years and never been caught.
correct....plus in order to register the bike with the DVLA it also needs type approval. Your choice of course but you should be advised that any hacking device will make your bike illegal.and you intend using it on public roads in the main...................and if you want to continue this thread it should be in the derestricting section which is headed with necessary legal warnings.
 

Long Way Home

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Jun 9, 2022
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Cornwall
The question I was asking, is how a US bike differs from a UK bike in terms of its speed regulation.
I appreciate that it’s probably semantics, but I don’t want to tune or derestrict the bike, merely set it to a different region.
The legalities and practicalities of doing such a thing are at this point moot. If speed is the issue, I can quite easily break a number of limits without assistance and in most cases, without knowledge as well, as I don’t have any means of measuring speed.
 

Doomanic

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The question I was asking, is how a US bike differs from a UK bike in terms of its speed regulation.
The software to access the system is proprietary and region locked. That is to say a UK shop cannot access the US severs and vice versa.
I don’t want to tune or derestrict the bike, merely set it to a different region.
The only way to set the bike to USA is take it there and get a Bosch dealer to set it to USA.
 

Long Way Home

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Jun 9, 2022
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Has anyone actually got in trouble or been stopped for suspected 'tampering'? Who would actually stop you & check it out?
It's only likely in an urban environment and then, only if unsocial behaviour or an accident is involved. It's still not legal though, but neither are many seemingly day to day situations. UK law states that it’s illegal to linger after a funeral, for example.
 

Voluptua

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Oct 4, 2020
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If you ran into a child, someone might start asking. But perhaps that's not the point. As a group we have to maintain the positive attitude of the powers-that-be towards ebiking. At present we can go just about anywhere an unassisted bike can go. So bridlepaths and shared tracks are open. Going 20mph on the road is probably not going to arouse attention, but scaring granny and her dog at a local beauty spot will get us a bad name.
 

Long Way Home

New Member
Jun 9, 2022
22
10
Cornwall
IAt present we can go just about anywhere an unassisted bike can go. So bridlepaths and shared tracks are open. Going 20mph on the road is probably not going to arouse attention, but scaring granny and her dog at a local beauty spot will get us a bad name.

That has been the case so far, but it might change, as ebikes give additional mobility to conscientious riders and the anti-social alike. This sees more bikes in general out on the trails, footpaths and other open spaces. I have already noticed additional erosion in areas on the commons caused by mtbs in general, but a portion of those are additional riders on bikes that would not normally have the wherewithal or ability to venture out into.
Speed is a red herring, the real problem is going to be the increased numbers of riders and with them, the increased number of idiots that will always make up a percentage of the total. Some of my rides are fairly remote and it is very unusual to see another bike, but if I do, it's likely to be an ebike, as not many people could be arsed to put the effort in to get there by self propelled means alone.
 
Last edited:

Apps28

Member
Sep 15, 2020
4
3
Yorkshire
I have just joined the forum and am new to ebikes in general, in fact, my bike is yet to arrive, but I have a question regarding the performance difference between the US and UK/EU versions of essentially the same bike and that is...

What is it that actually limits the UK/EU bikes to 15.5mpg that allows some US bikes to 20mph? Is it a software region lock or is it in the speed sensor hardware?

My Trek Powerfly is going to be a commuter, but I'm concerned that the paltry limit of 15.5mph is going to be more of a nuisance than help, as I am likely to be riding at or just above this when cruising. Most regular riders of non assisted pedal bikes, will be quite capable of cruising at well in excess of the UK limitations and the cut off could well make the commute a pain and I'm trying to avoid using the car whenever possible.

Raising the limit to the US 20mph would actually have a large impact on my commute time and fatigue levels, making the commute enjoyable, rather than a grind.



Pre covid I asked a friend that lives in Canada to price me a us/can levo and shipping to the uk for the very reason that I wanted the faster bike.
The bikes themselves are cheaper in the states so together with shipping worked out just under the equivalent uk price.
However, some further digging revealed that should the bike or more importantly the motor have to go to a dealer, Specialized are very strict on compliance with uk law and would therefore change it to comply…. no point in the long run.
that was of course for a specialised and other manufacturers may be different.
I actually bought a trek rail in the end, absolutely love it and don’t find 15/16 mph an issue.
 

Long Way Home

New Member
Jun 9, 2022
22
10
Cornwall
I have now put close to 500miles on my bike and can comfortably say that a limit of 15.5mph, is not really enough for a commute. 20mph would be a significant increase and knock 16 minutes off of my journey time.
for others thinking of trying to forgoe their cars, the current UK speed restriction might well be a deal breaker.

To mitigate the issue, I have invested in a larger front chainring and have a closer ratio cassette to install, when I get the time. This will help prevent pedalling out on descents and spread the gear use a bit better, moving from 10-51 to 10-45.
10-51 gearing seems too low for an e-bike to me, even an emtb. I don’t use the 51 much at all, even on my non assisted bike.
 

venicenerd

New Member
Feb 18, 2023
18
4
Barcelona
The only way to set the bike to USA is take it there and get a Bosch dealer to set it to USA.
@Doomanic Is this actually confirmed to work, though? Could I take my Bosch Performance CX (Smart System) Motor over to the US and have it re-flashed there and then bring it back to Europe? I’m not talking about brining my entire bike to the US. Just the motor.

Also what would happen with over the air (via Flo app) firmware updates after that? Would the remain on US? Or would even that flash me back to the EU version?
 

Doomanic

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Also what would happen with over the air (via Flo app) firmware updates after that? Would the remain on US? Or would even that flash me back to the EU version?

Honestly, I have no idea. I have a pre-Smart Bosch so OTA updates are witchcraft to me.

Also, your plan is a little extreme for an extra 7kmh. Are chips/dongles/whatever available for the Smart System? If so, just do that. Your bike is just as illegal either way so why not do it in the cheapest/simplest way possible?
 

venicenerd

New Member
Feb 18, 2023
18
4
Barcelona
Honestly, I have no idea. I have a pre-Smart Bosch so OTA updates are witchcraft to me.

Also, your plan is a little extreme for an extra 7kmh. Are chips/dongles/whatever available for the Smart System? If so, just do that. Your bike is just as illegal either way so why not do it in the cheapest/simplest way possible?
Yeah I would probably try the chips first but as they seem to be still really unreliable I would love to have a backup option. Just don’t want to be stuck with at 6k bike at 25km/h. That would really piss me off lol
 

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