Hi,
Thanks for the reply.
I quite like the idea of doing a conversion so good to hear you recommend it.
I have a Kona Lavadome hard tail mountain bike which I do light trail riding on. It's just for fun so only requirement would be reliable and strong pulling power up hills. Also would like throttle option as I'm used to motorbikes so like the idea of the throttle option.
Many thanks in advance.
Iain
The most popular route for cheap kits on here is
BMS Battery or
GreenBikeKit that are both located in Hong Kong/China and will ship to UK for a reasonable price*.. These two companies may be related we're not sure, they have much the same products and similar pricing with a few differences here and there.
Kit Choice
You can get a kit with the motor built into a wheel ready to fit, just have to choose front/rear and order the right wheel size and rim colour.. the kits are cheap but with decent quality motors, costing around £80 which includes the controller with a control panel, thumb throttle and pedal sensor, brake lever motor cut-out switches, everything you need. The kits come in different voltages (24v/36v/48v) and different motor ratings (250/350/500 Watts). The higher the voltage and wattage, the faster the motor will go..but if you want to stay road legal you're limited to a 250W motor... for general use with a good balance of speed and hill climbing power, I'd recommend a 250W 36v kit. If you prefer and have more budget, you can hand select what motor you use and buy a higher quality branded one separate and then have it custom built into a wheel rim. There's a guy on here called Catsnapper who does that for a reasonable price.
Battery choice
You'll need to buy a battery on top of that which they also supply.. I'd recommend a 10Ah battery as a minimum which will cost you about £115 for Lithium-Ion. I have a 36v 10Ah Lithium-Ion from BMS and it weighs only 2.3kg so not too heavy and the batteries are a proven technology so you can't really go wrong. 10Ah will get you about 4-6 miles on throttle only using full power, depending on your weight, and maybe 30-40 miles on pedal assist full power. I find 10Ah will get me up even the steepest hills without pedalling (even on a 26" 21kg bike) but saying that, I'm only a lightweight at 9 stone ;-)
You can get smaller "bottle batteries" now that will fit on the mainframe and look more discrete. However they are usually limited in capacity due to smaller size so you might only get 8Ah or 9Ah. You can buy two though of course and swap them out. If you're going for a big capacity battery for more hill climbing power and longer distance (15Ah or 20Ah) it probably makes sense to get a rack mounted incased battery and a purpose rack for it. Although you could just do what many do, and put a battery without case inside a rack bag or panniers, to reduce weight and make the bike look less electric. Probably depends on how you plan to use the bike and whether you need to leave it parked anywhere.
Front v Rear?
I don't think there's much difference really between front v rear wheel hub motors, maybe there's some, but not significant. I know some people here favour one over the other. I think the main benefit of front wheel is the ease of fitting..you won't have to mess with your gears. If you're considering rear wheel, you may have to downgrade your gears to 7 or 6-speed. For rear wheel though, I think the benefit is that the motor is more hidden and so the bike looks less-electric. Think about where you're going to mount your battery (on a rack, or on the handlebar with a bag?)..and that may help you decide whether to choose front or rear motor, it maybe makes more sense to have the motor closer to the battery as that means less cabling across the frame of the bike..
Drop-outs space and torque arms
Whether you go for front or rear, check your drop out width first and make sure there's adequate space for the motor (you will need 135mm for rear and 100mm for front). Normally with a 250W 36V motor you won't need to worry about torque or fitting torque arms (although some people like to do it as a precaution). If your bike is steel frame or steel fork, it's not likely to be an issue..with an aluminium fork, it's something to consider for front hub. Rear drops are usually fine even aluminium won't need any torque arms at this level of power.
LCD panels and more speed control
I purchased a Chinese kit from a company in Austria called
rftec which is pretty much the same as what BMS/Green Bike Kit supply, except mine had a fancy LCD console for the controller with more control over the motor power and pedal assist-levels. Because of the LCD console I had to pay a price premium (I think I paid about £270+shipping for the kit without battery). There are other suppliers that will support kits and/or motors with these LCD consoles cheaper from China.. but if you want more control than the basic kit panel (which usually has on/off and 3 speeds) what you can do now is buy a
speedict ebike computer for about £63 if you have a compatible mobile phone, it will work wirelessly via Bluetooth allowing you to see your speed/distance and control different aspects of the motor speed, throttle response and pedal assist levels etc. You'll need a smartphone running Android to get full benefit, but I think it will work with Java phones too but with less features.
I did a front wheel conversion a couple of years ago on a 26" folding MTB which was my first proper e-bike and it was very easy, not very challenging at all. However I had to improve and extend the wiring a bit which required fitting new connectors and doing some soldering, nothing major though, if you can change a fuse you can do it ;-) I've never had a days problem with my bike or kit, and the 36v 10Ah battery is still going strong which came from BMS Battery. I'm now just starting a second build (I've got the self-building bug like many on here!) and this time I'm doing a more challenging rear wheel custom wheel build for a 16" wheel folding bike. I'm buying all my parts from BMS Battery this time and planning to use a speedict with it.
* Don't forget when you're buying from overseas you'll have to pay VAT @ 20% + Duty about 3% and possibly a £15 "VAT deferral/clearance fee" to the courier, although I find if you just pay the import taxes and ignore the fee they don't bother pursuing it ;-)
I would definitely recommend the DIY route if you're happy with your bike and want to save some money.. I'm on my second conversion now and would never consider buying a ready made bike.. it's a really good experience going the DIY route, you learn a lot, but more importantly end up with a bike exactly to suit your liking and needs. 
