General purchase advice needed

[shanye]

Hi, All...

My partner (she's 50, not especially fit) suffers with a condition called Fibromyalgia. It causes her significant pain and makes it difficult for her to get about. It is beoming increasingly difficult for her to cycle, although we both enjoy getting out into the fresh air.

One thought is that a hub conversion might help her. We are looking at low speed, sub-20 miles range cycle assistance with the possibility of the occasional need to use the motor as a 'get me home' measure (still within the 20 miles - the absolute maximum distance when we might need to use the motor without assistance is 10 miles).

We're on a really tight budget, and there are no guarantees this will work for her anyway, so we are reluctant to go all-out and spend a fortune.

I have seen 250W - 350W hub kits on ebay at less than £180. The battery seems to be an area where a great deal of money might be required, so I wondered, given our requirements, if a lead acid battery might be a better bet. If we got two batteries, I could carry a back-up on my own bike so if she ran out of juice, we would be covered. This could almost half the size of the battery she would carry on her bike.

I was hoping to get everything covered for £250 maximum.

Question: Am I being completely unrealistic?

Thanks

shanye

 

[banbury frank]

Hi

What you have described is what we specialize in but A kit costs more than a thousand pounds BUT It will do the JOB you can come and try one where about are you an how much is the partners weight If it is not a rude Question you can PM me if you don't want to put on public forum

I can recommend a kit from china at a low cost But low support

What bike have you to convert

Frank

 

[NRG]

Difficult, unfortunately low cost means low support and backup...exactly the opposite of what somebody needs on a tight budget....catch 22

SLAs may be the way to go but capacity is limited and therefore range will be too...also their weight (~9Kg) is a significant penalty but if you can live with that then it may be a solution for you. Be aware that the extra weight will make the bike much harder to ride without power....

Capacity is reduced from what is says on the battery by something called the Peukert effect, simply put capacity will be approx 30% down on whats stated, so 10Ah becomes 7Ah, given an average energy consumption of 14~18Wh / mile you would expect to get 18 to 14 miles range from a 36v SLA...

To get 36v you will need 3 batteries (forget 24v) and some way of mounting them as low down as possible on the bike. SLA's will need replacing more often than Li-Ion types but the cost each time will be lower around ~£90....go for the deep-discharge types

 

[TwoBikes]

I can second NRG when he says to forget 24V, if you definitely need to be able to get home on throttle only, up inclines. I use 24V lead-acid on one of my cycles, but it won't go up hills without pedal assistance.

 

[kitchenman]

To get 36v you will need 3 batteries (forget 24v)

Umm. I've got LI-ion 24v and have done 30 miles in slow speed mode and 15 miles easily in high speed mode! ...

 

[NRG]

Yes, and.....? I was talking about SLAs 24v @ 7Ah is only 168Wh...range will be around 10miles or less on average.....

 

[kitchenman]

Yes, and.....? I was talking about SLAs 24v @ 7Ah is only 168Wh...range will be around 10miles or less on average.....

I see! ... that reminds me I dont know what Ah my 24v LI-ion battery is ...

 

[spankdanny]

can recommend BMS battery. I bought their 36v 350 watt front hub kit with wheel for £160.Battery would be about the same again. Took about 8 weeks to arrive from china but they kept me informed. I would say you need to be fairly mechanically minded cos my forks and front disc brakes needed a bit of modifying to get everything to fit.

 

[Cyclezee]

Hi, All...

I was hoping to get everything covered for £250 maximum.

Question: Am I being completely unrealistic?

Thanks

shanye

Hi Shayne,

I empathise with your problem, but I think £250 is being very optomistic.

You might be luck enough to find a complete bike on the used market, but be careful and ask for advice here before spending money.

Where are you located? I have bikes your partner could try with no commitment to buy.

 

[kitchenman]

can recommend BMS battery. I bought their 36v 350 watt front hub kit with wheel for £160.Battery would be about the same again. Took about 8 weeks to arrive from china but they kept me informed. I would say you need to be fairly mechanically minded cos my forks and front disc brakes needed a bit of modifying to get everything to fit.

Hi spankdanny, where did you get your battery? What is your bike? What was your budget? What did you end up paying? ... When did you fit it? Are you commuting? Whats your route like? Go any photos?
Thanks ...

 

[TwoBikes]

spankdanny is not the first to mention slow delivery from BMS Battery. Presumably this is the cheap option. Can someone tell me how to select this option when buying from BMS Battery? I have bought from them and have only been offered a choice of expensive courier services. The one I chose was fast (3 days) and reliable, but practically doubled the cost of the order!

 

[spankdanny]

Hi kitchenman. I am using two 36v 2.6 ah hitachi powertool batteries I bought off ebay for £25 each. I also bought two chargers for £20 each and keep one at home and one at work. My route is about 6 miles, pretty flat really but with a bit of a hill coming home. I mostly pedal, for the exercise, and just use the motor on the uphill bits or if theres a headwind. I think I should have got the rear hub motor in hindsite. When off road,on steep inclines,the bpm front hub wants to just wheelspin even if you keep your weight over the front. Like I said it did take a bit of modifying to get everything to fit (the axle wouldnt fit in any forks I had so had to file them by about 1mm). There is a photo in the members gallery. cheers dan

 

[spankdanny]

I think there is only one delivery option. My shipping costs were $110 whereas the hub and wheel were only $140.I dont think its too expensive considering the weight.It wasnt the shipping that took the time it was them processing the order.

 

[shanye]

Lots of feedback - thanks everyone.

I am reasonably mechanically and technically minded, so I am not overly daunted by zero after sales support from the vendor. My concerns with going cheap are more around the quality of the parts, rather than the mechanics of attaching them to a bike. I would imagine it is very easy to purchase something for a a low price which will fail quite quickly. And obviously, as the question suggests, I am not entirely sure what to expect in terms of performance in considering Hub voltage, wattage and battery output - it sounds quite a bit more complicated than just doing the basic maths. So, that said, I am happy enough with the concept of ordering something cheap if I can be sure the quality is OK and the vendor legitimate.

The bike being converted is a basic Claude Butler alloy wheeled/framed ATB with front suspension - the sort of thing you can get for £250. It's not hugely light, but it has city tyres to reduce rolling resistance, and is good and strong. My partner likes it better than the more upright classic road bikes she has tried. She weighs about 63Kg, I would guess (touchy subject - I don't go there).

It is sounding increasingly as though I need to rethink using SLA, especially if the advice is to go to 36V. Spankdanny seems to be suggesting that something in the region of £320 all in might be possible. I'm anxious about buying a complete bike because I know batteries have a limited life, and it will be difficult to know if the battery is good. Question: Am I right in assuming that brush-less motors are pretty much immune to physical wear, apart from bearings?

I am still thinking that I might be able to help my partner by sharing the weight load with her. If she only has to carry half the battery weight (because I am using my muscle to carry the other half), then that might have some impact on what we need? I also wondered about how realistic it might be for me to carry the entire battery pack until she needs it. Maybe we could go as usual, then, at the bottom of any significant hill, or when she tires, we could attach the battery and give her the advantage of assistance? Do Hubs offer any resistance when disconnected from a battery pack?

thanks for your replies so far.

shanye

 

[banbury frank]

Hi looking a t your bike convert It with a Rear kit and battery from BMS China


Allow 4/6 weeks for delivery that is the worst case

pay by PayPal so your money is safe


Bafang BPM 36V500W Rear Driving Bike Conversion Kit - BMSBATTERY



Just select wheel size


36V10Ah Li-Ion Alloy Shell EBike Battery Pack - BMSBATTERY

Battery weight 3.5 kilos rear Rack mounted slide on off rack with key lock comes with mounting plate


I chose the Bafang Kit as that is the motor fitted to most ebikes as standard not the cheapest also 500 watts power to spare

complete kit £350 delivered

Hope this Helps

Frank

 

[shanye]

Thanks, Frank.

That's looking good. It says 'disc brake', but I am not clear if that means disc brake only or disc brake possible - partner's bike has rim brakes. I noticed that the other motor on the page says specifically that it is compatible with both, which is why the question arises. Would you happen to know?

thanks

shanye

 

[Cyclezee]

Hi Shayne,

I think Frank is giving you good advice and don't think you find anything worth having cheaper.
As for brakes, you will be able to use your existing rim brakes.

Good luck