Message posted by ultraquasar on 29/9/2017 at 6:21pm
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I've looked into e-bikes myself but the weight detracts from the enjoyment of cycling when the batteries go flat, so I ended up going back to a lightweight hardtail mountain bike.
So you can get a hub kit to retro fit your existing bikes, I think theres a few dealers here in the UK who will do this for you, or you can go for a pre-made ebike and they break down into two formats.
One type is the hub driven one's, the other is a crank pedal type, namely Bosch last time I looked.
Danger of the Bosch if going offroad so probably wont apply if you are after a city type bike, is when you whack the crank on a log you might be jumping/bunny hopping over, you can do some damage to it which becomes costly.
All of them tend to have Lithium batteries as these give a nice constant amount of power unlike say NiCad or Lead Acid batteries, but I havent seen any Lead Acid due to the weight except some very early homemade ones made by enthusiasts some years back.
Some ebikes also claim to reclaim or generate electricity when going down hill, but the problem is, the hubs can generate alot of electricity and the lithium batteries can only really take upto about 30% of whats generated at best. Lithiums need to be charged slowly but constantly, they are less tolerant to variation than NiCad or Lead Acid which is why we still use Lead Acid on cars.
Now if someone did a hybrid battery, ie lithium and lead acid, then the regen hubs could charge the lead acid's which can handle the spikes of electricity being generated and then use those first before tapping into the more constant lithium batteries, but I havent seen anything like this and have made some enquiries into getting a prototype frame built to incorporate this but not been too successful finding the type of frame I would need.
But even something like that would still add weight and to be honest I find a lightweight bike is probably best.
It might pay to check out a couple of second hand lightweight bikes because I dont think you'll find much even secondhand for your budget, but prices are always coming down. Any bike hire shops may off load old stock which might be worth checking out online and asking.
I would also check out the cost of spares as its a fairly new sector so constant development and improvement could make the spares for the earliest bikes hard to come by.
If considering a lightweight bike, you might like this forum http://weightweenies.starbike.com/, they are fanatics at saving weight, and interestingly the bloke who holds the world record for the lightest bike, modded it and now also have the world record for the lightest e-bike, but the batteries/motor are really only used for climbing the swiss mountains where he lives and he's a retired engineer so spent a bit of time getting it all to work.
If doing retrofit ehubs, you can buy a number of kits from dealers or if you want to take the risk you can buy individual kits off places like alibaba.com but I wouldnt like to say how any warranty issues would be handled buying from a far, but they will be cheaper to buy this way.
With regard to the hubs, basically the amount of copper wound around the hub determines whether you have a fast top speed but slow to get upto to speed, or you have a hub wound for torque so you get up to speed quickly but the top speed wont be so fast.
Whilst you can buy kits to go faster than the EU/UK mandated speed limit, it wont be road legal so any retro fit kits you might go for will need to be legal. Retro fit kits also tend to have a battery pack which sits on a parcel rack over the back wheel and some may only have push button on/off controllers which will contribute to your effort but might not be enough to propel you up hill without peddling. You can get more fancy controllers which will let you choose from 3 different amounts of effort the hubs can contribute to your efforts.
There is also a Danish (iirc) read wheel which is a smart rear wheel. Here's the youtube link for it as this might be a retrofit alternative you might like if you have smart phones. https://www.youtube.com/watch?v=S10GMfG2NMY
Its pretty neat but cant say what range you would get.
Theres lot of youtube video's showing purpose built and homemade e bikes, some sensible some not so sensible, the one mad englishman who built a 9KW homemade one which is probably doing something in the region of 50-70mph judging by how fast he zips along the roads, and these DIY'ers can give out useful info.