I am trying to decide which pedelec conversion kit to buy for my hybrid roadster... It would be nice if the cheapest was a good rival for the dearest.
When buying a conversion kit, unfortunately, you rapidly find yourself in the world of economics.
How so? Because price depends on who gets paid. Many kits sold in England were made in China. For example, you cite Oxydrive, and I found this quote on the forum, apparently from Oxydrive, "We no longer use Suzhou Bafang motors on any of our bikes or kits. All motors are now our own branded motors which have been developed in partnership with one of the Chinese motor manufacturers."
The closer you get to China, the fewer who clip the ticket.
However, there are alternatives to get closer to the source. Thanks to the internet and global shipping, you can find less expensive products that should perform as well, or in some cases better.
I'm writing from the other side of the globe, New Zealand, where we have seriously steep gradients and the e-bikes on offer are not great bikes. So we set out to find good bikes and good conversion kits. The first thing we found was you can buy German (expensive & excellent) or you can buy Chinese, with a a range of quality.
If you have €2,650 buy a Vivax kit. They list a UK dealer in Somerset. We have not tested it, but it sounds fantastic.
If you buy in China, the safest vendor is an Englishman in Shanghai named Paul, who goes by the moniker Cell-Man on endless sphere (another ebike forum). Paul at emissions-free.com sells the Mac motor kit and the MXUS kit and he sets it up to be UK legal. He sells the A123 battery which is more advanced than Li-Po and Li-ion and has the additional advantage that it does not catch fire or explode... which while unlikely for the typical consumer is now seeing airlines and post making Lithium harder to ship. The MXUS kit is the lowest power and the complete kit (not including battery or shipping) is US$175. The 39V 9.2Ah A123 Pack is US$350 (we ordered custom-built 6.7 Ah battery for $275 because we wanted less weight). For your use, that would probably be the best kit. It is a front motor, and we would suggest you select the thumb throttle with cruise button (he gives you a choice of thumb, half or full grip [like a motorbike throttle]) and we suggest you ask for a quote to upgrade to the Infineon controller. You also can describe your needs and he can tune the kit as the controller is programmable.
The kit comes plug-and-play, which means that the connectors can only be hooked up one way. You specify your wheel size and it comes as part of the kit (or you can order spokes and have a shop lace in your existing rim), as does the controller, throttle, ebrake handles, PAS (Pedal Pulse Assist Sensor). Paul's A123 batteries come with slightly more power.. 39v instead of 36, 52 volt instead of 48, and the difference with the MXUS was just enough to give the right boost on 39V.
Support? Unfortunately, when the MXUS controller arrived it did not work, which baffled Paul because he had tested and tuned it for our requirements . He agreed to send another one at no charge in the next order we placed with him. Instead we decided to go with the upgraded controller by Infineon. He credited the difference. His support is good; the only caveat that he is a small operation and can get overwhelmed by emails. Being a native Englishman in China makes a world of difference.
To be clear, we have no connection to Paul, and do not get paid to write recommendations (and we pay the same price as you will for kits). We found that of the vendors in China, he is the best for the newbie. If you are in a hurry, he quotes EMS air shipping, and of all the Chinese vendors, he is the fastest to get it into the post. He also is one of the few who will send surface mail. It will take a month or two to arrive, but it costs a lot less. You pay using PayPal.
The first motor kit we bought from Paul was his $350US, 500W Hi Torque motor kit with a 48v (52v) triangle battery which turns a MTB into a new type of vehicle, an exceptionally light motorbike - it is fast (52kph), powerful up steep hills, utterly illegal on the roads (our max is 300W) and too much for us. At our age, something like that is asking for trouble. So we put it up for sale, and it sold in an instant to someone who is knowledgeable and knows what he is buying. Your needs suggest you want a lower voltage, lower wattage motor from Paul, not the 500W kits. We have not yet tried his MAC 350W, which he says is more powerful than the MXUS. The MXUS helps us up the hills, and the rest of the time it is off.
To tell some of the don't-go-there stories, we bought a Cute100 front motor from another Chinese vendor easy to find on the Internet, whose English was awful. The kit was cheaper, has less power, and we had to solder on all the connectors. We spent the first two hours just labelling everything just to make sure we would not fry something. It was OK, and half the price of the MXUS, but not worth the savings. We had a problem that turned out to be a melted connector, but when we tried to get assistance, the vendor was hopeless. From that vendor, it's best to think of it like buying at an auction... cheap, but once you paid you're on your own.
In addition, from another Chinese vendor that is well known in eBike circles, we bought a 36V "bottle battery" to match the Cute100. Again, very poor English, and zilch in terms of technical ability. We had a problem when the battery quit. No help from the vendor, but the endless sphere forum has a lot of experts, and they suggested it was a bad BMS circuit board. It was and the vendor did send us a new board for free, but said we had to pay shipping (which was more than the board. So we ordered two boards to be safe). We had to install it, and the manufacturer changed where one of the wires plugged in, so we had to solder an extension. We crossed that vendor off our Christmas list as well.
We also have Bafang 200w motor that came as part of a Ulisse Greenspark purchased in Italy and flown back for free on Emirates. Nice bike, works fine, so we now are talking to Bafang in China about ordering one of their new CST motors as a trial on our latest bike a Montague Crosstown full-sized 700c folding bike. This is a rear motor that uses the Cassette type gear cluster (most Chinese motors still use the older threaded style). We will be testing it on the Montague using a 32 pulse/cycle BB sensor (this senses when you are pedalling, it fits in the bottom bracket, and is 4X as sensitive as the PAS sensor), two hidden wire brake sensors (HWBS) instead of e-brake levers on the handlebars and our original 36v 8.8ah bottle battery. The intent with this kit is to keep the handlebars uncluttered and let it feel more like bike riding with that assist when the hills would otherwise have our legs and lungs screaming. All it will have on the handlebars is the C910 display, about the size of a business card.
If this kit works, we have lined up a couple of dealers who may want to order them by the hundreds because there is such a demand for affordable conversions. We can't report on that one yet, because it has not arrived.
So, in addition to the English vendors who pitched their products in answer to your posted question here, be aware that you can buy with one degree of separation from the Chinese manufacture and save a lot of money. With Paul you will get good product, good service and good support. However, you will be half a globe away, and if you are the type who wants it all sorted for you, buy local. Also, be aware that with any kit, something may not fit. For example, Chinese front wheel kits tend to come with 10mm axles. Many European bikes have 9mm slots, which means you (or someone who knows what they are doing) have to very carefully grind out half a mm on each side of the front fork slot.
If you buy a pre-made bike like the Kalkhoff, for example, you can be confident it will all work fine. If you want to save money and buy the Greenspark (or UK equivalent) using Chinese component ebike, it is likely that the sort of stuff we are doing, testing to find what works best, has already been done. But those folks in England or Italy who do that testing need to eat, so you pay the extra so they can stay in business.
Finally, to explain, we are a charitable trust in New Zealand that has a project to get more Kiwis on bikes. Most of the bikes sold here in bike shops are sold by enthusiastic young bike fanatics who are either into extreme mountain bikes or extreme road bikes. So they convince every old duffer who comes in to kit themselves out with zoom-zoom stuff totally inappropriate for someone who grew up on a Raleigh, and today needs almost exactly what they had when they were a kid. Except of course that we have killer hills, and the ebike kit is a godsend for aging knees, out-of-shape legs and ancient lungs.
To be clear, we are not in the business of selling kits or bikes, but rather in testing stuff out and then looking for the sweet spot between price and performance. We have little patience for salesmen who over-pitch their products, but at the same time, we have not tried everything. So we don't disparage what we don't know, but only talk about what we do know.
