hi all

[sil4ps]

hello all.
totally new to all this electric stuff. i am a keen cyclist but at 51 i struggle to do a 15 mile each way commute and work all day in between. i also have a steep hill to get up each way

i went to my local e bike shop and had a look but nothing was very appealing under 2 grand
and especially limited to 250watts or spending 1500 - 2k on a half decent conversion that can zip along. i'm not bothered about staying legal as alot of my journey is off road.
i would be converting an older 2002 specialised rockhopper with v brakes and eager to do it but have reservations.

ive been looking at all the chinese options for complete kits and there is a waterproof 1000 watt front wheel kit with a 48v 10ah lifepo4 battery delivered to uk for 800 dollars.

my question is really am i asking for trouble. am i throwing my money away or has anyone had a good experience buying from china.
my reckoning is everything is made in china anyway and according to wickipedia there are 120 million of them in use in china so they must work.

any help much appreciated.

 

[Gdread]

Hi, I'm a similar age and struggled with a much shorter commute on an unpowered bike. I had a bad knee and the physio recommended cycling as a good exercise. I bought a 250w kit from Greenbikekit. No hassles except for getting stung on the duty. Kit was good quality and easy to fit. Racks have been a real pain though and there is always something to tinker with so it's almost a hobby and not just a mode of transport and the knee is no longer a problem

You'll find strong views on here on the 'off-road' issue, 30 miles round trip is a long commute, you need to think about charging, proper lights and properly mounting the battery especially if off road maybe using a frame bag etc.

Either way, best of luck and lots of advice will follow my post

 

[sil4ps]

hi
thanks for the info. out of interest what was the duty % they charged you for importing the kit.
also the offroad is smooth so will be like on road in terms of kit mountings.

 

[103Alex1]

That kit looks overkill for what you likely need and powerful front hub motors create their own issues as regards forks etc. Are you able to charge 'on-bike' at work ? If not then ease of disconnecting and removing battery to recharge is an issue and the larger the battery the more cumbersome this gets so if you can get your required mileage without recharging at work it would make things much less hasstle.

A 500W geared rear hub motor with 48V battery if you are big & heavy, need assist speeds over 23mph or want to ride on throttle only else 36V is plenty. A 36V 20Ah battery would do you the round trip easily without charging at work as well as providing the current needed for good speeds, especially if you didn't ride flat-out on 'full throttle' (or max PAS assist) and cruise most of the journey without too many stop/starts, else a 48V 15Ah has same capacity but might prove more power hungry for the same distance reducing range like for like.

If you can currently cycle 30 miles a day without assist then you might not even need anything like this much power. But it does make a very noticeable difference riding 25kg of bike, especially at lower speeds, and day in day out if you're knackered a bike of the above spec would allow you to vastly reduce pedalling effort and still get home just as fast if not faster.

 

[sil4ps]

hi
103alex1 thanks for info. i can charge at work no probs.
if i could keep up 23mph i'm happy to work a bit with the motor
i have 2 very steep hills so thought i needed as much amps as poss.
the 1000 watt motor appeals to the grin factor when conditions allow.

my main concern is buying from china and wasting my money.

 

[Deleted member 4366]

i would be converting an older 2002 specialised rockhopper with v brakes and eager to do it but have reservations.

ive been looking at all the chinese options for complete kits and there is a waterproof 1000 watt front wheel kit with a 48v 10ah lifepo4 battery delivered to uk for 800 dollars.

my question is really am i asking for trouble. am i throwing my money away or has anyone had a good experience buying from china.

There's hardly any problems buying from China, but you don't get any warranty; however, in the rare event that something does go wrong,the stuff is cheap enough to replace/upgrade.

A front motor of 1000w is not a good idea on a Rockhopper unless you want to change the forks to crappy steel ones.

10 aH LiFePO4 is a bit light for 1000w. Unless it's something special, it''ll struggle to provide the current. 15 aH would be better. Having said that, some of the cheaper gaffa tape-wrapped ones can be problematic. The cells can easily be damaged, connections can break, plus, they're relatively heavy.

First, you need to say how fast you want to go, how heavy you are, how far you want to go and what sort of hills you encounter, then we can advise you on the best kits.

 

[sil4ps]

hi d8veh

Im 14 stone and want to go steady 20 to 25mph
I took the shocks off my bike years ago and put steel mtb forks on so no probs there
the journey is 15 miles each way with 1 big steep hill each way poss 2 depending on my route.
i will be pedalling to assist battery but just dont want to be knackered which puts me off doing it regularly.

all help appreciated.

 

[RobF]

You really don't need 1000w and you could easily end up with a virtually unusable contraption which is always breaking down.

Frank from Xipi is a member on here and could sort you with a quick, but sensible and reliable kit:

Welcome to Xipi

You say most of the run is off-road, but if you plan to crack along at 20mph+, day in, day out, you want something that is quiet and unobtrusive or you might get unwanted attention.

 

[KirstinS]

I would agree that 1000w seems overkill for your purposes

Just to give an indication I have 250w 36v 8fun kit that I run at 44.4v . I happily nip along at 23mph with very little rider effort and can get up some steep old hills with more input. Goes down to 20mph as battery runs down

 

[Deleted member 4366]

hi d8veh

Im 14 stone and want to go steady 20 to 25mph
I took the shocks off my bike years ago and put steel mtb forks on so no probs there
the journey is 15 miles each way with 1 big steep hill each way poss 2 depending on my route.
i will be pedalling to assist battery but just dont want to be knackered which puts me off doing it regularly.

all help appreciated.

A 1000w front motor could work, but I've got a feeling that it wouldn't be very pleasant for 15 miles each way at over 20 mph. If it were my bike, I'd get some decent used air forks from Ebay, change the font brake to a good hydraulic disc, and fit a rear motor kit. If you decide on that front motor as a solution, I'd leave the LiFePO4 battery, and get a lighter LiMnNiCo one. You need to find out the winding speed (rpm) of any motor that you buy because all motors have a fixed maximum speed at their nominal voltage.

 

[Yamdude]

I would agree that 1000w seems overkill for your purposes

Just to give an indication I have 250w 36v 8fun kit that I run at 44.4v . I happily nip along at 23mph with very little rider effort and can get up some steep old hills with more input. Goes down to 20mph as battery runs down

How do you get the 8fun kit to do that speed ?

 

[sil4ps]

A 1000w front motor could work, but I've got a feeling that it wouldn't be very pleasant for 15 miles each way at over 20 mph. If it were my bike, I'd get some decent used air forks from Ebay, change the font brake to a good hydraulic disc, and fit a rear motor kit. If you decide on that front motor as a solution, I'd leave the LiFePO4 battery, and get a lighter LiMnNiCo one. You need to find out the winding speed (rpm) of any motor that you buy because all motors have a fixed maximum speed at their nominal voltage.

Hi, what is the benefit of the rear motor, is it more stable??
i would have to change gearing, and more time and problems if i get a puncture. If i pedal with the motor i will have 2 wheel drive,

I can see the benefit of air shocks and will look at that,

what is a liMnNico battery and where can i find one, all the blurb says that LIFEPO4 is the best technology for durability.

The 1000W motor has an RPM of 430 and Efficiency>80%

thanks for all your help.

 

[Deleted member 4366]

A rear motor can be mounted more securely. Small motors are OK in the front, but the weight and power of a front motor affects your steering.

You don't have to change your gearing if you get a CST motor. Bafang, Xofo and MXUS all do a similar 500w one.

LiMnNiCo is the most common Ebike battery chemistry. The same as laptop batteries. They're cheaper and lighter than LiFePO4.

430 rpm = 32mph. It will have good efficiency at 25mph, but will be very poor at less than 16mph. These type of motors are well suited to riding at a constant sustained speed of 25mph. Not so good for stop-start journeys or hills. You need to feed them with about 25 amps, which I doubt that that 10aH LiFePO4 can provide. You'd need to ask the supplier the C-rating. Even if it could, 10aH will only get you about 10 miles at that speed.

You could ask Frank about his Xipi kits, which use a similar setup. He should be able to give fairly accurate figures for performance.
Welcome to Xipi

 

[KirstinS]

How do you get the 8fun kit to do that speed ?

Don't want to hijack the thread so, in short,

1) add a 7.4v booster battery in series to give 44.4v nominal total voltage. Mine is homemade and built from 18650 cells with 2s balance leads. I also use a lipo alarm to ensure cells don't go below 3v each

2) change the controller from stock to a BMS battery KU65 and leave it unrestricted . If you connect 2 wires it restricts to 15mph

That's it really !

Search for "booster battery" to find threads on this. There was a whole lot of learning on way !

 

[sil4ps]

A rear motor can be mounted more securely. Small motors are OK in the front, but the weight and power of a front motor affects your steering.

You don't have to change your gearing if you get a CST motor. Bafang, Xofo and MXUS all do a similar 500w one.

LiMnNiCo is the most common Ebike battery chemistry. The same as laptop batteries. They're cheaper and lighter than LiFePO4.

430 rpm = 32mph. It will have good efficiency at 25mph, but will be very poor at less than 16mph. These type of motors are well suited to riding at a constant sustained speed of 25mph. Not so good for stop-start journeys or hills. You need to feed them with about 25 amps, which I doubt that that 10aH LiFePO4 can provide. You'd need to ask the supplier the C-rating. Even if it could, 10aH will only get you about 10 miles at that speed.

You could ask Frank about his Xipi kits, which use a similar setup. He should be able to give fairly accurate figures for performance.
Welcome to Xipi

ok thanks for that, I was considering a 48V 20ah battery but maybe i would be better off going for a 500Watt motor with 36V 20AH battery would give a better even performance perhaps.

What speed would i get from a 500W and would that be more suited to a front wheel drive??

What is the C- rating and sorry for all the questions, i'm learning fast.

cheers.

 

[Yamdude]

Don't want to hijack the thread so, in short,

1) add a 7.4v booster battery in series to give 44.4v nominal total voltage. Mine is homemade and built from 18650 cells with 2s balance leads. I also use a lipo alarm to ensure cells don't go below 3v each

2) change the controller from stock to a BMS battery KU65 and leave it unrestricted . If you connect 2 wires it restricts to 15mph

That's it really !

Search for "booster battery" to find threads on this. There was a whole lot of learning on way !

Ok, thanks, I have the 8fun kit on my bike.... I may research this more at sometime, if I feel I want more speed at some stage.

 

[Deleted member 4366]

The C rating is the amount of current that it can give compared to its capacity. A 10aH 1C can give 10 amps, a 2C 20 amps, a 15aH 3C 44 amps, etc.

There's a lot of things you have to balance when making decisions about kits. Weight and hills determine the torque you need. Your max speed is determined by the motor RPM and battery voltage. The controller has to give the current you need for the torque. The motor has to be able to handle the current. The battery has to be able to provide the current. It's capacity affects how far you can go. The bigger your motor and battery, the more power and speed you get, but the heavier it is, the harder to install, and the more cumbersome becomes your bike. High C-rated batteries can be smaller and lighter, but you don't go so far.

For me, the best balance of all these things comes from a 500w 270rpm 36v geared rear hub-motor with 20aH 36v battery and a 25 -30 amp (depending on weight) controller. You will be able to pedal comfortably on the flat at about 22mph, manage serious hills without much effort, and reach a distance of 50 to 70 miles. That's my personal preference. I've tried lots of motors with different speeds and powers. I have double and triple motored bikes. I like them all, but you can't beat the simplicity and robustness of a simple rear hub-motor.

When you go faster than that, the experience is not so much like cycling, and it would be more dangerous on cycle paths etc. Your bike would be heavier and less manageable. At first, it seems like fun, but soon becomes tedious. A motorcycle then becomes more attractive, especially when you also consider the cost.

 

[GT3]

OP, my commute is similar (16 hilly miles) but there was no way I was capable of making the trip on an ordinary bike.

I started with a 1000W motor with lead acids. Big power and speed demands big batteries which result in a heavy bike and frequent breakages. I have been through numerous systems but am currently very pleased with a 250W Q100 motor and 36V 10.4 Ah bottle battery. The journey takes under an hour and I charge once a day at home. The battery is solidly mounted and the bike a pleasure to ride when the battery is dead.

If you think about it, you only need the power up hill. Downhill you're going fast enough without power. On the flat you will manage a reasonable speed without power, it's the hills that kill.

I've purchased from China three times now and never had problems at their end. The last order from BMS took some time to be posted, but once sent arrived within 48 hours.

 

[sil4ps]

OP, my commute is similar (16 hilly miles) but there was no way I was capable of making the trip on an ordinary bike.

I started with a 1000W motor with lead acids. Big power and speed demands big batteries which result in a heavy bike and frequent breakages. I have been through numerous systems but am currently very pleased with a 250W Q100 motor and 36V 10.4 Ah bottle battery. The journey takes under an hour and I charge once a day at home. The battery is solidly mounted and the bike a pleasure to ride when the battery is dead.

If you think about it, you only need the power up hill. Downhill you're going fast enough without power. On the flat you will manage a reasonable speed without power, it's the hills that kill.

I've purchased from China three times now and never had problems at their end. The last order from BMS took some time to be posted, but once sent arrived within 48 hours.

hi, thanks for all the info.

What sort of speed do you get from the 250W Q100 and what range, Also how heavy are you and lastly should i worry about being waterproof, there is one seller on ebay who specifically lists waterproof kits 250W up to 1500Watt alongside non waterproof.

many thanks.

 

[Gdread]

hi
thanks for the info. out of interest what was the duty % they charged you for importing the kit.
also the offroad is smooth so will be like on road in terms of kit mountings.

It was about 10% from memory