Big fella, first bie sub £1500....

[disneycjd]

Hi everyone
I am pleased to have found this forum. I have read a lot of posts and now wondering if you could share some views. I am looking for my first e bike. Thinking of a touring model and had liked the Cube Katmandu 650 but they are just too expensive at the moment. As a large chap (120KG and 6ft) I wanted something with decent power and so was looking at bikes with the Bosch Performance CX Gen4 crank.
I also looked at the RadPower Rhino as the price was keen and they didboht a 750w and 250w version (although I cannot see apart from the 500w if there is any power difference). I would also like to use some trails on private land so the ones where I could maybe increase the power and then make legal again for the road would be good.
I would like mud gaurds and lights and something that can do at least 40 miles on a charge.
IF you have any suggestions I would love to hear of them.
Thanks!

 

[Raboa]

Hi, what about the Whoosh Bug Bear.

Woosh Big Bear Plus | MTB electric bicycle from Woosh

The Woosh Big Bear Plus, a very sturdy electric bike for the traditionally built riders with 36V 15AH/17AH battery from Woosh.

wooshbikes.co.uk

Excellent company and post on here.

 

[disneycjd]

Thanks. I had looked at whoosh and as an original Essex boy was keen on this company. The front hub motor puts me off making it heavy and difficult on trails. I’d before a crank motor to be fair.

 

[Raboa]

I don't know if this would be of interest.

Bumblebee police auction site, buy a second hand bike of them and fit a crank drive motor.

Bumblebee Auctions

Thanks

 

[Fishy]

"I would also like to use some trails on private land so the ones where I could maybe increase the power and then make legal again for the road would be good."

No such thing as 'making it legal again' if it can exceed 250 watts/15.5MPH, it's illegal.

 

[disneycjd]

"I would also like to use some trails on private land so the ones where I could maybe increase the power and then make legal again for the road would be good."

No such thing as 'making it legal again' if it can exceed 250 watts/15.5MPH, it's illegal.

Interesting as RadPower Bikes say their 750w is legal here in the UK and have that confirmed by DVLA and isn't there a few bikes that allow you to switch the power? I heard of a 1000w which can switch from 250w to 1000w?
Thanks

 

[vfr400]

It depends what you mean by legal. They're not legal as a pedelec bicycle, but are legal as a registered L1eA vehicle.

The rule is absolutely clear for a licence-free pedelec: The motor can be rated at no more than 250w, so you can't use a 750w or 1000w one and cut down the power, i.e. the restriction is on the motor itself, not how much power you push through it, which is rather convenient for us because it means that we;re not limited on output power, while as in the USA, the limit is 750w output power, not rated power. Luckily, there are a few "250w" motors that can handle a lot of power.

AFAICS from the only court case I've seen about illegal pedelecs, the court applies the law like this:

1.Does all power cut above 15.5 mph?
2. Is the motor rated at no more than 250W?
3. Does the vehicle have pedals that can propel it without the motor?

Probably, now you can add:
4. Does the motor stop when you stop pedalling?

If the answer to all those questions is yes, you'll most likely walk away free.

 

[disneycjd]

It depends what you mean by legal. They're not legal as a pedelec bicycle, but are legal as a registered L1eA vehicle.

The rule is absolutely clear for a licence-free pedelec: The motor can be rated at no more than 250w, so you can't use a 750w or 1000w one and cut down the power, i.e. the restriction is on the motor itself, not how much power you push through it, which is rather convenient for us because it means that we;re not limited on output power, while as in the USA, the limit is 750w output power, not rated power. Luckily, there are a few "250w" motors that can handle a lot of power.

Thank you. Thats helpful. So https://www.e-bikesdirect.co.uk/brands/cyclotricity/ex-demo-cyclotricity-stealth-1000w-dual-power-electric-bike is something that wouldnt work?

For the 250w motors that have power? Do you mean the Bosch Performance CX Gen4? for instance

thanks

 

[vfr400]

Thank you. Thats helpful. So https://www.e-bikesdirect.co.uk/brands/cyclotricity/ex-demo-cyclotricity-stealth-1000w-dual-power-electric-bike is something that wouldnt work?

For the 250w motors that have power? Do you mean the Bosch Performance CX Gen4? for instance

thanks

The first 250 crank motors were advertised as around 40NM torque with a max speed of 15.5 mph. Today, there are 250w crank-motors that are advertised as 110NM with a top speed of 15.5 mph.

Power =torque x speed.
Hello!

It's the same with hub-motors. Basically, torque is proportional to current, so you can get more torque by increasing the current. There's always a safety margin built into the motor specifications, so when the designer/engineer decides on the rating, it's a question of how much safety margin they build in and how much you want to exploit it. Motors like the 250W Bafang BPM, CST and SWX02 seem to have very large safety margins.

 

[KirstinS]

"I would also like to use some trails on private land so the ones where I could maybe increase the power and then make legal again for the road would be good."

No such thing as 'making it legal again' if it can exceed 250 watts/15.5MPH, it's illegal.

Well, I belive there is a way to do this with some Chinese system. And I've done it and belive it to be legal.

But its proper DIY and come with risks of frying controllers or motors or both

However, for interest I do via a booster battery

1. Splicing a connector into the power to the contoller. I like XT60, say female
2. Make a male blank. By that I mean a connector that simply reconnects the circuit. For legal use keep it in
3. For private land use, remove the blank and plug in a battery. I tend to use 11.1v lipo packs and chuck them in my pannier.
4. You are now shoving 48v nominal through a 36v system for more speed and torque.

For example my xf07 250w 36,v front hub which is pretty small can do 24mph this way. Unplug the booster and it is back to about 15.5mph

Once again you risk frying stuff this way but I am pretty sure this keeps the bike legal for both applications. Obviously doing 24mph on a public road isnt, only on private

 

[disneycjd]

So.... thank you all so much for all of this. So would I be right in saying actually to shift the big fella up the hills at full speed actually its not the 750w motor vs 250w motor....its about the NM that the motor outputs? Big batteries are for range...

Thanks!

 

[vfr400]

That's about it when you're buying an OEM bike. When you build your own, you have more control over the NM.

 

[Woosh]

So.... thank you all so much for all of this. So would I be right in saying actually to shift the big fella up the hills at full speed actually its not the 750w motor vs 250w motor....its about the NM that the motor outputs? Big batteries are for range...

Thanks!

you will need both, torque and power, because you need to maintain a minimum speed. Let's say you weigh 120kg and you ride a 30kg bike up a 10% hill. Your minimal speed should really be more than 6mph.
The required mechanical power for a rider weighing 120kg climbing a 10% gradient at 6mph is: 475W, let's say human input is 75W.
The motor can't convert electrical power to mechanical power at 100% efficiency, that's why the right selection of motor is very important. A good motor can still give you 60%-80% conversion yield, a badly chosen motor gives you 40% or even less.
At 60% yield, your battery and controller need to deliver (475W - 75W)/0.6 = 666W
of which 266W will turn into heat.
At 40% yield, your battery and controller need to deliver (475W - 75W)/0.4 = 1,000W
of which 600W will turn into heat.
So an efficient motor at low revs is a good motor for a heavy rider. That means a large geared hub motor like the Bafang BPM to be within your budget:
https://www.ebikes.ca/tools/simulator.html?motor=MBPM&grade=10&mass=150&hp=75&axis=mph

Crank drive motors will be good for you too because it's easier to retain high motor yield at low revs by shifting to your granny gear. However, you need to balance the good against the bad: if you have a rear hub motor, the motor does most of the work, your drive train only has to cope with your pedalling. If you have a crank drive, your drive train has to take the full workload. In the example above, if you have a hub motor, your drive train copes with 75W, if you have a crank drive motor, the full 475W. The wear and tear are naturally much more with a crank drive.
BTW, you are allowed to exceed momentarily the 250W when climbing a hill at less than 15mph.

 

[Fishy]

Well, I belive there is a way to do this with some Chinese system. And I've done it and belive it to be legal.

But its proper DIY and come with risks of frying controllers or motors or both

However, for interest I do via a booster battery

1. Splicing a connector into the power to the contoller. I like XT60, say female
2. Make a male blank. By that I mean a connector that simply reconnects the circuit. For legal use keep it in
3. For private land use, remove the blank and plug in a battery. I tend to use 11.1v lipo packs and chuck them in my pannier.
4. You are now shoving 48v nominal through a 36v system for more speed and torque.

For example my xf07 250w 36,v front hub which is pretty small can do 24mph this way. Unplug the booster and it is back to about 15.5mph

Once again you risk frying stuff this way but I am pretty sure this keeps the bike legal for both applications. Obviously doing 24mph on a public road isnt, only on private

Interesting, it was my understanding that any so called "off road switch", ie, any mechanism that allowed the user to increase power or speed above the legal limits, was still deemed illegal whether in use or not.
I could be wrong though.

 

[vfr400]

Interesting, it was my understanding that any so called "off road switch", ie, any mechanism that allowed the user to increase power or speed above the legal limits, was still deemed illegal whether in use or not.
I could be wrong though.

The off-road switch is only illegal if it releases the 15.5mph speed limit. As I already pointed out, there is no limit on power used. If you had a switch that switched from a 250w motor to a 500w one or brought in an additional motor, it would be illegal too.

 

[Fishy]

But in KirstinsS example, it increased speed to 24mph, so......

 

[vfr400]

But in KirstinsS example, it increased speed to 24mph, so......

He only uses his booster battery on the part of his journey where he runs along some private land. The owner of the estate gave him permission.

 

[Fishy]

He only uses his booster battery on the part of his journey where he runs along some private land. The owner of the estate gave him permission.

That's not the point, the fact that he can increase speed above the legal limits would make the bike illegal, even if you only used the extra speed on private land.
It's the ability to change it that makes it illegal, not whether you do it on road or not.

 

[vfr400]

That's not the point, the fact that he can increase speed above the legal limits would make the bike illegal, even if you only used the extra speed on private land.
It's the ability to change it that makes it illegal, not whether you do it on road or not.

There's no law against substituting your battery, neither is there any law against carrying a booster battery in your pocked.

We've debated this many time. The law says that off-road switches are not allowed. I can imagine that whoever wrote that law, had the idea about a simple on/off switch somewhere that released the speed limit. How far does that go? All electric bikes can be made to go faster. It's just a question of how quickly it can be done. The general interpretation and consensus is that anything you can do conveniently while riding the bike would be illegal, but even that is open to interpretation. A large number of bikes can be adjusted by pressing a sequence of buttons on the LCD. Some by bluetooth using a smart phone, others by a plugging in a USB cable, etc. Even Bosch systems can be adjusted by USB and smartphone while riding along.

 

[Fishy]

That's all well and good, we all know you can increase the speed of a pedelec, but surely the bottom line is, if a bike gives motor assistance above 15.5mph, then it's not legal.

 

[vfr400]

That's all well and good, we all know you can increase the speed of a pedelec, but surely the bottom line is, if a bike gives motor assistance above 15.5mph, then it's not legal.

If it doesn't go over 15.5mph and doesn't have an "off-road switch" when being ridden on the road, it's legal.