Hi from County Durham

[CaptainCrash71]

Hi, just trying to get into e-bikes on a budget. I'm a 46 year old paramedic, who really needs to lose some weight and get fit(ter).
I've got a really nice Giant terrago mountain bike, which I've had for a few years but have barely ridden it. We moved house shortly after buying it, and it's very hilly where we live, so riding stopped being fun. I've slowly got more and more un-fit, to the point now I daren't get my bike out.
I've just changed job location and will be working about 6-7 miles away from home. So, now's a good time for me to use my bike for work.
I've had a test ride on a mid-drive kalkhoff bike at my local shop, but at £1700 it's worth more than my car
I've decided to build my own battery, using Panasonic 30Q cells, 36v 12ah. I don't need mega long distance, no more than 20 miles, so this should be big enough.
I'm favouring a mid-drive at the moment due to a couple of long hills on the way to work, but if someone wants to persuade me otherwise to an alternative, I'm all ears.

 

[Benjahmin]

Hi Crash,
Conversion will certainly get you out in hills, it's exactly why I did it.

I would consider a hub drive for commuting (either front or rear) because they are pretty bombproof, wear the drive train less, and have a more just let it do it's thaing style of usage. All you have to do is be in the right gear for yourself(as opposed to the motor) ride and enjoy the scenery. There is little or no maintenance on a hub motor, if they are fitted correctly, and you'll get all the help you need here.
There will be others along to say exactly the opposite!
Battery wise, the cell choice sounds good, with a high discharge rate I believe. 12Ah will equate to 432Wh. You can reckon on 10-20Wh/mile. Giving you a range of approx 21 up to 43. But consider, this will depend on fitness, terrain, wind, weight, temperature, tiredness after along day etc. Also the battery probably will not give you its full theoretical capacity and this will deteriorate quicker the deeper the charging cycles. Plus, once you get the ebike grin as a permanent fixture, you will want to go further.
So go as large as you can afford/fit.
Welcome to the slightly obsessive but highly enjoyable world of e bike conversion.
May the grin be with you.

 

[CaptainCrash71]

Thanks for the reply Benjahmin, seems a friendly site so far.
The problem I have with a hub motor, (and feel free to correct me if I'm wrong) is that I have heard a front hub can be a problem going up hills, and for a rear wheel I would need to find a cassette type wheel, and they seem quite expensive. There are some horrendous hills around here, we're 300m above sea level and on top of a hill. There's also quite a lot of wind as it's very exposed.
I also don't like the look of the bigger hub motors, and I'm doubting a 250w will manage the bigger hills.
My journey home is almost all uphill, and I work 12+ hour shifts, so I don't want to have to struggle home with a heavy bike with minimal assistance. Or even worse, my bike just ending up back in the garage where it's been for the past 8 years.
Again, I'm only basing this from anecdotal evidence (mostly from this site), so please feel free to correct me, I'd like nothing more than to find an easy and cost effective solution . I really don't want my build to run over £500 all in, which I feel I can easily do with a Tongsheng or Bafang system.
As for the battery, one of the reasons I am building my own is so I can future proof it and add cells to it at a later date if I feel it necessary.
Thanks
Alan

 

[Deleted member 4366]

Building your own battery won't be cheaper than a ready-made one, in case that's what you're thinking. You have to add up the cost of everything, including installation.

You need:
Cells
Insulators
Nickel strip
14g wire
Connectors
Heatshrink for wires
Gaffa tape or large heatshrink for the cell-pack
BMS
Test/measuring equipment
Case or bag
Mounting system
Spot welder
Dremmel with cutting disc (unless you can find slotted nickel strip)
Soldering equipment
Skill
Know-how
Luck

Those Youtube videos make it look easy, but they often have serious flaws in them, where they miss out vital areas of safety.

I think it's worthwhile to make your own battery if you think you'll most likely be making several and you want to use it as a learning experience, but don't do it if you think you think you're going to get a single cheap battery out of it.

If you're heavy (say >90kg), unfit and have hills, you should be thinking about 48v and a relatively slow wind motor. You should aim for a motor in the range 200 to 260 rpm at 48v. If you're very heavy, it needs to be at the bottom of that range. Motor speed is a critical characteristic. Don't buy any motor or kit without knowing what its winding speed is - expressed eithr as RPM at a nominal voltage or kV.

 

[RobF]

Did the Kalkhoff provide enough assistance?

They are quite perky, but no balls of fire, so if the answer is 'yes' a 36v hub motor would also suit.

I like crank drives, but you would be restricted to a single chain ring at the front.

A front hub motor is my suggestion.

Grip on asphalt with widish, not over-inflated, tyres should be a problem.

You can always lean forward a bit or stand on the pedals.

 

[CaptainCrash71]

Hi d8veh, it's not just a cost cutting thing, although I have done an itemised costing, and my battery will cost me approx. £150 made with quality new cells and using lots of stuff I already have. I have seen batteries around this price , but I doubt their cells are of a decent quality.
The main reason for me was to make a custom fit battery as my frame size is pretty small, and I can't find a bottle type battery that will fit inside of my frame.
I believe I have the equipment and knowledge to safely and effectively make my own battery. I suppose I'll find out the hard way if at all goes awry.
I weigh about 80kgs, but am quite unfit. I don't want the bike to be too much like a moped, because I can probably buy a moped cheaper, I want to have to put in some work, increasingly so until I'm fit enough to ditch the motor all together.
I'm having trouble finding reasonably priced hub motor suppliers in the UK. I have looked at cyclotricity, but by the time you add on an LCD display and PAS they become rather expensive. I have found this
https://www.amazon.co.uk/36V350W28-Wheel-Cassette-Motor-Conversion/dp/B01LZWWP5G/ref=sr_1_2?ie=UTF8&qid=1520168830&sr=8-2&keywords=cassette+wheel+electric+bike
from yose power. 36v 350w, not too obtrusive and will take my existing cassette. Decent price and I think enough power to get me up the hills hopefully. The only thing is I can't find any info/reviews on this wheel, and the ad doesn't mention windings etc.
Thanks for all the input, like I've said, I'm open to other ideas.
Cheers
Alan

 

[CaptainCrash71]

Hi RobF
to be fair I only had a 15 minute test ride, and there were no big hills, but I was surprised how much assistance it gave. I went out on my bike a few weeks ago and was knackered after about 15 mins, with the kalkhoff I didn't break a sweat.
Can anyone recommend a hub motor supplier who will get me what I want at a reasonable price?

 

[Benjahmin]

Ignore the 250W rating of motors. This is merely a continuous rating that means the motor will not heat if fed that amperage continually. The actual max power is the max rating of the controller. From my experiance it's hard to heat a hub up. Keep at 8mph or above when climbing and there will be no problem. Hubs are most efficient at 50-80% of their rated speed.
As you can see, I live in W.Wales. My bike is front hub (Ezee) and I haven't found a hill that's beat me yet (I'm 65 and a leisure cyclist). I don't think that a young buck, such as yourself, will have a problem. The variable assist levels mean you can do as much or as little work as you want.
There is a thread somewhere on the yosepower kits. I think, with the right controller, it will suit you.
If you run a 36v motor from a 48v battery and controller you will get approx 30% more torque. Happy hill climbing.

 

[Deleted member 4366]

Those kits are quite good for the money. At 80kg you should be OK at 36v. If you need more torque, there's a setting in the controller to turn it up a bit, or you can solder the shunt for a bit more. You can go as high as 20 amps, which would give the same torque as 48v at 15A.

 

[CaptainCrash71]

That's good to know d8veh. Am I right in thinking if I was to buy one of these kits I would be able to upgrade the controller to a beefier one to eek more power out of it at a later date if I felt it necessary?
I was really trying to avoid going the 48v route as I will be struggling with battery size, but again, nothing I couldn't work around.
I really wanted to avoid buying bits from all over, I would much prefer a kit.

 

[Woosh]

I was really trying to avoid going the 48v route as I will be struggling with battery size, but again, nothing I couldn't work around.

some 48V kits have the same footprint as their 36V cousins.

http://wooshbikes.co.uk/?hubkits#swx02-48v-kit

They weigh the same too.

 

[Hightechpete]

Hi CaptainCrash71,
A few short weeks ago I was in the same position as you, bikes gathering cobwebs, but had never ridden an ebike, I can only speak from my limited experience thus far.

I bought and fitted a front wheel Cyclotricity kit to my old steel framed Raleigh racer as a sort of 'suck it and see', £150 for the throttle only option. I live in Wales and have rheumatoid arthritis, I was concerned that a small motor would not provide enough help.

To say I am now a big fan would be an understatement, don't worry about hills or you fitness level, its amazing how well these little motors deal with it all. You can put as much or as little effort as you like, it still seems to fly up the hills.

I don't want to promote any particular brand, but unless you're an accomplished bike mechanic it would be best to choose one that can offer some backup.

I've got the bug, and I'm already looking to either electrify my 'best' bike, or more likely get a go anywhere mountain ebike.

 

[Kinninvie]

How steep and long is your biggest hill?
I live in Co Durham and my 1000watt direct drive front hub was not able to assist me up the biggest hills here so I changed it for a Bafang mid drive and can go anywhere now.

 

[CaptainCrash71]

I live in Tow Law, so we’re at the top of a big hill, and surrounded by loads of other big hills. I was looking at the Bafang or the Tongsheng mid drives originally, but couldn’t make up my mind. Is it not too restrictive losing the front chainring(s). That was my only concern really. I was favouring the Tongsheng simply because of the simpler/tidier setup, no brake sensors or throttle required. But I’ve also heard good things about the Bafang. Which model did you get?
I’m guessing from the name you live near Barney, I used to work as a paramedic in Weardale, so spent a lot of time in Teasdale. You’ve got plenty of big hills there

 

[Hightechpete]

You seem to be favoring a mid drive, I guess it's because you live in a hilly area, disadvantages are that they are comparatively expensive and result in more wear and tear on the drivetrain.
Before you take the plunge, beg, borrow or steal a geared hub drive ebike and try some big hills, I promise you will be seriously impressed.

 

[Deleted member 4366]

How steep and long is your biggest hill?
I live in Co Durham and my 1000watt direct drive front hub was not able to assist me up the biggest hills here so I changed it for a Bafang mid drive and can go anywhere now.

Climbing is not a strong point of those 1000w motors. What you need is torque, not speed. Those motors don't make full power until they reach about 30 mph. At 10mph climbing speed, you'd be lucky to get 200w. There's many hub motors that can provide more than enough torque for your hills. Some of the small ones can produce over 400w of output power at that speed.

 

[Kinninvie]

I live in Tow Law, so we’re at the top of a big hill, and surrounded by loads of other big hills. I was looking at the Bafang or the Tongsheng mid drives originally, but couldn’t make up my mind. Is it not too restrictive losing the front chainring(s). That was my only concern really. I was favouring the Tongsheng simply because of the simpler/tidier setup, no brake sensors or throttle required. But I’ve also heard good things about the Bafang. Which model did you get?
I’m guessing from the name you live near Barney, I used to work as a paramedic in Weardale, so spent a lot of time in Teasdale. You’ve got plenty of big hills there

My Bafangs are 750 watt and 1000 watt but then I weigh 17 stone and carry over 2 stone of batteries on long runs!
At your weight a 250 watt Bafang will be ok especially if you get a wide range rear cassette say 11-36T or even 11-40T and then a front chainring of 42T is all you need.
I have an 11-40 which came from China and was only £10.
I dont use brake sensors but have a pushbutton attached that cuts the power in an emergency.

 

[chris_n]

I don't think a 250w geared hub will be able to maintain anywhere near 10mph on the hills around Tow Law! I only have limited experience of geared hub motors but do know the hills around Tow Law well. I do know the geared hub motors (Q100) I have ridden have had nowhere near enough power to deal with them. Maybe d8veh's comments about slow wind motors at 48v would be successful but I very much doubt if anything less than a Q128h could manage at 36v.
I would probably go for a Bafang with a smaller chain ring and an 11-40 or 42 cassette if a ready built bike is too expensive.

 

[Deleted member 4366]

I put a Q85 in a Brompton. It could climb a 14% hill with a 100kg on board without pedalling. That was at 36v and 14 amps.

A Q128 at 48v and 20A should manage 28% with the same bike and rider.

A Xiongda at 48v and 15A can easily manage 30% hills with a 100kg rider and 26" wheels.

Generally, hub-motors can produce more power than crank-drives, but to get them to climb, they need to spin at a reasonable speed, which means that you need one with either a high internal reduction ratio or a small wheel or both. One with a low winding speed will be more efficient when climbing, which means greater efficiency and less heat.

 

[anotherkiwi]

Have a look at the GSM without controller from Woosh - add a 17A KT sine wave controller and a 48v battery you will climb anything with ease. If you aren't concerned with higher top speeds a 38 tooth chainring and wide ratio 11-40 cassette setup will provide climbing speeds at near the legal limit on most hills.