Mobility Bike???

[graywolf]

New here, but figured this was the place to get expert advice. I have read a lot here, and this post is mainly to check my thinking resulting from that reading.

What is going on is that I have a cardio problem (afib). I bought an inexpensive 20" wheel folding bike to keep in the back of my vehicle to bop around town and to get some exercise. However, the fact that I do not get enough blood to my muscles is more of a problem than I expected. So I have been thinking of going electric. The problem here is that what I need is almost the opposite of what most everybody else wants. Low power, low speed (15mph max, sometimes only 10mph), light weight. I want to get some exercise riding it, my muscles are fine they just do not get enough blood flow to go more than a couple three miles on their own; and unfortunately exercise is not going to improve that situation.

The Chinese made folder I have actually seems to be intended as the basis of a cheap ebike. Alloy frame (135mm OLD, horizontal dropouts, 7-speed freewheel), steel fork (90mm OLD), the frame looks designed to take a battery behind the seat post. In fact I have seen some ebikes advertised that look like they are using the same frame. That's the good part.

My thoughts are running to a Cute Q85 (high torque version --there be hills around here) on the front wheel with a couple of RC Helicopter type LiPo's (5-6s 8ah) for power. I say 5s or 6s because I notice that the 5s can be hard to come by. The point of the LiPo's is that I can order them from a USA based warehouse and not have to worry about the crazy rules for international shipping that seem to have come out recently.

Alternatively, a Cute Q100 on the rear. That would have the advantage that it could be laced into a 700c rim and used on my old Town type bike, if for some reason the folder didn't work out. A third possibility is the small 250w GNG mid-drive but that seems overkill for what I need.

Now, into the something different part, I would like to either be able govern the motor to 10mph, or switch the batteries to parallel. My thinking is that if I do that I can, with a letter from my doctor, probably convince the cops that it is a mobility device, so that in heavy traffic areas I can ride it on the sidewalks. On the two block long tourist area downtown I would simply get off and walk the bike. It would be nice if the modes could be switched with a key lock switch, with the key required for the high speed (oxymoron) mode.

My questions: Am I completely out of my mind? Is there a better solution. Are the Cute or other similar motors available here in the USA, or do I have to order from Asia? Is there something I am missing?

I am open to suggestions that keep in mind that this needs to be; inexpensive, lightweight, and fairly easy to setup.

 

[Drunkskunk]

Sounds like a good solid use of Ebike technology.

I would go with the rear motor, as it opens more possabilities. But under powering the motor isn't the answer. Infact If you need the motor at times, you want it to be fully capable of meeting the need. There are other ways to limit the power.

One way is with a device called a Cycle Analyst. The direct plug in model is capable of setting a top speed and a top power output for your bike. It also acts as a full gauge package with speedometer, odometer, trip meter, volt meter, amp meter, watt meter, and a host of other features you'll need on an Ebike.

Another solution is a 3 speed switch. Extremely handy for riding as you can have one speed for slow speeds, another for medium, and a third for full power. It switches on the fly, and when you need more power, you thumb the switch and go. Usefull when some big dog decides you look like a chew toy. Or some jealous husband decides you look like his wife's last chew toy. Ed Lyen is the only person I know offering them pre wired.

The exact motor for your needs is hard to judge, but the MUXUS 350watt motor I have is a very capable little motor, especialy at lower speeds. 350 watts is about the smallest motor I would use if I thought I might someday need the motor alone to get me home. And I have had to do just that a couple of times.

As for batteries, Lipo is small but risky. Unless you have experiance with Lipo, it's not the best solution. LiFePO4 are a much better choice, and there are plenty of options around.

You can run a motor at a lower voltage, but there are issues with the LVC and amp draw. 36 volts is about the lowest practicle voltage. You can pick a motor winding capable of 20mph 48 volts then run it at 36 volts, but in the long run, you're better off with some other form of speed govenor.

I don't know of any US vendors for the Andana Cute motors. Lyen is in the US for the controller and can be found through this forum. The Cycle Analyst comes out of Canada from Justin at Ebikes.ca. The 350watt motor I mentioned is from the US, from Jason at Ebikekit.com. The best batteries I know of come from China by way of Paul, who has earned his good reputation here. his site is em3ev.com

 

[docnjoj]

Hey graywolf! You are definately on the right track. I too have A-fib but was able to build up to about 400 miles a month using my e-trike. I gotta agree with Drunkskunk that there are way better limiting devices than a little wimpy motor. Definately good advice. We ride heavy trikes and really need the power on hills and to rapidly get across streets. Around here we can ride the sidewalks to the Multi-use trail, but I would not ride either trike on crowded town streets. Too easy to hurt others even if you go very slow. Do you live in a bike-friendly area?
otherDoc

 

[graywolf]

I feel that both of you missed the last where it has to be both inexpensive & lightweight.

I believe that a CA will add about $100 to the build. Lifepo4 will add about $200 + 2-3# to the build. I will have to check out that motor for price and weight.

From what I can find out the Q85 actually weighs about 5# (a bit heavier than they claim) the Q100 6# or so. There are a couple of lighter motors but they are a lot more expensive. The Q85 will fit in the 90mm dropouts on the front of my bike, but I tend to agree a rear motor is maybe a better bet, although at the power levels of these motors it probably does not matter a whole lot.

My understanding is that the KU63 controller can be quite easily modified to run 15-45 volts, it can also be modified to run higher amps although I do not feel I have a need for that in this case. From articles in these forums some people run these little motors on that controller at 44-45v and 18a (that is 800 watts max) while I am looking to run it at 36v 15a (540w) max and 16v 10a min (160w). That 16v comes as the minimum voltage you would want your 5s lipo pack to get down to in the case of running the 2 of them in parallel. If they are only run in series the minimum would be 32v, I am not sure what the amps would run in that case.

If I built my own wheel (lighter than the build the sell with the kit) the whole thing, Q85, 2x 5s 8ah lipo's, controller, et al, should not add more than 12# to the bike. That would put the bike at about 40# and it would still fold OK. I could still lift that in and out of the old Blazer. Add much more weight, and I would start having problems with that.

I understand the precautions needed with big LiPo batteries. I have excellent general knowledge of DC motors (I actually did the final testing and quality control for a multi-horsepower electric motor and control firm at one time). Am less qualified to deal with electronic controllers (they came out after my time).

I labeled this thread "Mobility Bike" for a reason. The bike is intended for use by handicapped people (me in this case) who can still balance a bicycle but who may not have 100% control. Did you know that they make motorized walkers? You might as well tell the people using them that they need a much bigger motor on it. If I need something faster than this build is intended to have, I would buy a 150cc motor scooter. This is intended to get a bit of exercise and to avoid the parking problems in the town center, not as a motor vehicle replacement.

 

[The fingers]

I got into the e-bike as a handicap issue, keeps me on it without killing myself. We moved and my commute distance more than tripled, and I was reduced to driving. The electric kit was a Godsend for me, and I wish all of my bikes had one.

 

[docnjoj]

Well I have to admit that trikes are not light. But I can actually rideon the sidewalk and into stores at 2mph if necessary. Of course I'm old but trikes are stable. If I had to transport one in a Blazer I would get one of those Harbor Freight rear baskets that support 500 lbs. Do you have a trailor hitch on the Blazer? A sheet of plywood 3/8 with holes drilled for lightening would serve as a ramp. Just sayin'
otherDoc

 

[graywolf]

Well I have to admit that trikes are not light. But I can actually rideon the sidewalk and into stores at 2mph if necessary. Of course I'm old but trikes are stable. If I had to transport one in a Blazer I would get one of those Harbor Freight rear baskets that support 500 lbs. Do you have a trailor hitch on the Blazer? A sheet of plywood 3/8 with holes drilled for lightening would serve as a ramp. Just sayin'
otherDoc

You are missing the point again. The weight the Blazer will handle is immaterial. The weight I can lift in and out is not. I store the bike in the back of the vehicle.

The speed the bike can be ridden at is immaterial, the speed the cops see it is capable of is not, if I want them to see it as a mobility device. Otherwise $181.50 fines are going to limit my use of the thing severely. The fine for not wearing a bicycle helmet is the same, they are really worried about you hurting yourself it appears (If you believe that, I have a bridge for sale, cheap). I figure if it takes a key to make it go faster, I can probably get away with it being a dual purpose machine.

I live in a town that still subscribes to the old values. e.g. Poor people can't fight back!

 

[Hyena]

You haven't said how far you need to go on a charge.
It sounds like you're primarily looking for pedal assist so why dont you power it from a single 8S lipo pack ? That keeps your size, weight and cost right down, along with minimising wiring complexity. Get a little cute motor as you've suggested or something like a small bafang (essentially the same thing) If you want to keep looks to a minimum get a little 6 fet controller too. You could hide it an the lipo pack inside a small saddle bag and the police would be none the wiser. Given your target application you're not going to be breaking any land speed records or have the ability to riding stupidly on it even if you wanted to so they'd have no cause to even pull you over. If however you need to rely on the bike to get you home with minimal or no pedalling input, then do as the others have suggested and get a more powerful motor. Mac, bafang bpm, bmc etc.
The golden motor smart pie could be a good option too but may not appeal to your weight or price constraints.

Where are you located ? It sounds like what you're after is well within the scope of the law in just about any country so that aspect needn't be a deterrant

 

[Samd]

As DOS Equus man says, I don't always suggest a cute, but this time I suggest a cute.

From the above, if there aren't many hills>5% on your hitlist, buy the stock 201 rpm q85 or q100 kit from greenbikekit perhaps. It'll arrive about 3-4 weeks from order, and unlike bmsbattery it is cheap to add a battery to your kit if you search all the greenbike kit options. The rims are cheapies but at that speed who cares for a sidewalk cruiser. I have no affiliation to greenbikekit BTW.

The stock "250W" controller they ship with it pulls about 14.5 amps without modding the shunt, at 41V hot off the simple laptop style charger on a bottle battery it'll dump 570 watts from battery at WOT into the controller. All WOT testing I did I couldn't get anything over 38 degrees celsius with a laser temp gauge.

You can get them to throw in other controllers for about 20 bucks more.

I recently took an Ezee front off a single speed city commuter and replaced it with a q100 for the same reasons. The cute is not on the same plane as a BPM/Ezee/Mac 1500W capable geared, but it still dumps enough juice to make the stock 19 tooth rear freewheel useless. I need to change the rear freewheel to a 16T as a result. Here's a comparison photo for size. A Bafang SWXK sits about in the middle for size.
http://www.endless-sphere.com/forums/viewtopic.php?f=6&t=45570#p664805

D8VEH seems to have had a good run with feeding them 700watts reliably without trouble. Mine went ok on the 500W 9FET for awhile (850W from battery) but was overkill. Groaned a special little pigsqueal on the 12FET at 1200W though! Took it all off when I saw what the stock kit controller was really pulling. And the stock controller stickers almost rival Hyena's 250W limiting sticker for authenticity

No giving me jib about pedaling Hyena. Someone's gotta do it.

EDIT: I should have added, that on the flat it'll happily do 10 to 15mph, pull about 150 to 200 watts and give you a range on a 36v battery pack of about one and a half mile per rated 'ampere hour' with a few hills thrown in.

 

[dogman dan]

Whatever you pick, you don't need a CA to limit it's speed. You can do that with the throttle. But a controller with a low speed jumper would make it easy to just plug in a wire and then the controller will limit speed to about 12 mph or less.

You are on the right track, get a small rear hubmotor, and run it on 36v lipo, or 24v lipo if you have a controller for 24v. Sounds like 300w or so will do your needs.

What is the issue with the town? No bikes on sidewalks? If the cops are gonna bust a bike, they'll bust your bike. You'll have to take your ticket to the Judge and hope he's not a nazi too. Some towns just suck, I've heard of towns were honest to god mobility scooters were forced to ride in the road.

Other places just bust a punk on a bike, and leave a courteous riding adult alone.

 

[graywolf]

Hyena, Realistically probably 5 miles. Not sure how an 8s 5.8a lipo would work for that. It looks like a 10s 5a might be a better solution. If I actually wanted to commute into town I would need 15 miles usable (let's not kill the batteries) range with the only safe route having a rather steep hill. I am in the mountains of North Carolina, USA. The State law allows ebikes no problem, but trying to get it considered a mobility device by the local law may be an exercise in futility.

Samd, I bookmarked your thread to read more closely later on. 1.5 miles per amp? That sounds doable with a 10s 5a lipo for running around downtown, although I still think a pair of 5-6s 8a would be better.

Dogman, Your comments about the cops is about right for this town. I have left a message both BMSBattery and GreenBikeKits, to see how they respond. A point, since FedEx will no longer accept Lithium batteries the shipping from GBK with a battery is very very high. As opposed to just very high for the kit without battery ($100).

Thanks guys, your comments are very useful helping me zero in on what to consider doing.

 

[Jeremy Harris]

I'm currently running a very light folder with a Q100 motor on the rear (sold as a GBK100 motor by Greenbikekit). I have some of the same issues as you, in that I need lightweight (I've just had abdominal surgery so this is even more important now!). One way to make getting the bike in and out of the car easier is just to unclip the battery. This happens automatically with my Swift folder, as the seat post has to come out to unlock the folding mechanism. I fitted the battery pack to the seat post and this breaks the load up a lot - I end up lifting the seat post, saddle and battery pack in (that weighs maybe 3.5 kg) then lift the rest of the bike in (which weighs around 12 kg). I find this a LOT easier than lifting my other electric folder, which weighs over 20kg, into the car.

I reckon a Q100 kit, with a lightweight battery pack (maybe one of the little bottle batteries) would suit your needs well. It add around 6kg or 7kg or so to the weight of the bike (GBK quote the total weight including the charger I think), but should give you just what you're after. As others have said, I'd opt to select the lower maximum speed limit on the controller (pretty sure this is an easy mod to a KU63, just a matter of connecting pad XS to ground) and that'd give you better low speed control on the throttle. This kit is about the cheapest that might suit your needs: http://www.greenbikekit.com/index.php/36v-250w-gbk-100f-front-driving-e-bike-kit-with-bottle-battery.html but still might push your budget. You might be able to trim $50 off the price by buying individual parts, but that depends how handy you are at putting things together.

 

[graywolf]

Thanks Jeremy. As it happens I just got a message from Alice Le at GBK, "If you want high torque for the bike, I recommend you to convert rear wheel; I recently convert my own bike with 85F motor, it is much lighter, but its torque is weaker than rear kit."

The idea of a saddlebag battery on the seat which I already remove due to the Brooks B66 is good. I was kind of thinking that the front motor would kind of balance my 220# on the rear of the bike. I was thinking of a handle bar pack battery, the controller on the head tube or a small front rack, and of course the Q85 in the front wheel. The real advantage to me of that setup is the idea that I could eventually mount an IGH in the rear wheel. Seems like for every advantage you have to trade another one.

Another trade off, I just discovered. Battery chargers that will charge 8-10s batteries seem to be twice as expensive as ones that will only go to 6s. In fact I have found one that will balance charge up to 4 6s batteries for only $60 + shipping of course. Some of this RC stuff is amazing.

if anyone is interested I took my old Etrex Ledgend GPS on the greenway today. One lap of a 0.75 mile loop gave me these figures 0.58 miles (part was under trees and could not get a lock), average speed 8 mph, max speed 12 mph, lowest speed 5 mph. This paved loop has a lot of mild ups and downs but only about a 10 foot max variation. I used gears 1-4 of 7. Max cadence estimated at 70 rpm. As you can tell from all that, I am not in good shape. I used to be able to do the loop in 5th or 6th gear equivalent at 70-75rpm. For what it is worth, we are at 3000-3300 feet altitude here. Ah well, I used to be able to walk thousands of miles too.

 

[Samd]

By all means convert the rear.
But you could still go front drive and just feed it a few more amps to compensate. Their base kit controller is still pulling nearly 500W from the battery with throttle wide open.

Sure the 85mm wide front motor is a bit thinner than the 100mm, but for what you want I'm not sure you'll see any appreciable difference. And if you did, you could just shove a 9 FET on it for takeoffs and run at a lower throttle for coasting.

Food for thought.

 

[dogman dan]

I'm still curious and confused why it matters if the cops call it a mobility device? No sidewalk riding law?

Chances are, if you are riding slow and courteous, they won't give a damn if an adult is on the sidewalk at times. It's punks hooning around they bust. But some towns do have thier Officer Obey, Barney Fife characters. Definitely, if you are hated by the cops already it's a problem.

A typical 36v low wattage gearmotor kit should do your needs. 5 ah of 10s lipo will get you 5-6 miles with no problems. Further at slower than 20 mph speeds. Hobby king, USA warehouse for fast easy ground ship.

 

[graywolf]

I'm still curious and confused why it matters if the cops call it a mobility device? No sidewalk riding law? .

EGGactly! Specifically "No bicycles on the sidewalks". And North Carolina has a state mandated $131.50 court cost. Win, lose, draw you still get to pay that if you get a ticket. Plus the $50 fine if you lose. Needless to say the whole thing is a revenue producing scheme. I found out about that mandatory court cost thing when I got a $30 seatbelt ticket awhile back, a university cop actually pulled me over for not wearing a seatbelt. They even charge the 131.50 when you do not go to court. I have about decided that you are right, they probably would give me a ticket for riding an actual mobility scooter on the sidewalk, maybe even a motorized wheelchair.

Meanwhile the town has separate laws that forbid skateboards and roller skates on the streets, and on the sidewalks; neither of which seem to be enforced at all. They are however specifically allowed in the crosswalks. The cops here, especially the young cops, and we seem to have a lot of young cops around here, do not seem to give warnings, they are ticket happy. Regular Barney Fife, "He was doing a solid one mile per hour over the speed limit, so I gave him a ticket" types, as you said. I have about decided the idea is unworkable here.

Hobby King USA was where I intended to get the batteries.

Interestingly, I get a total price for the kit (Q85 or Q100) with shipping of $235 from BMSBattery, and $211 from GreenBikeKit. Those is very close to GNG's total price for a mid-drive kit of $240. $70-100 for shipping seems outrageous. I guess I should check out just the motor, controller, and throttle to see if the shipping is cheaper.

 

[graywolf]

I have about given up on the idea of a mobility bike due to probable police hassles, so the dual range need goes out the window.

But some folks may be following this, so I will provide the results of my continued checking one prices.

Just the Q85 motor (or Q100), KU63 controller, and a throttle comes out to $144 (and some change in both cases) from Green Bike Kits, or $150 from BMS Battery. Shipping gets cut about in half by not having the whole wheel shipped. But it looks like with that and a single 6s (22.2v 8a nominal) LiPo & charger we are talking about $300 + rim & spokes. We are also talking about 8-9 pounds added to to the bicycle. so under 40 pounds total weight & this is with a rather heavy folding bicycle, you could go 7-8 pounds lighter with a more expensive one.

If my health was better, I would not be considering a motor for the bike. As it is, I need to figure out whether whether to go ahead with this, or save the money towards a down payment on a 150cc motor scooter which would save me enough on gasoline to make the payments on it. Unfortunately, at my income level it is a one or the other choice.

 

[graywolf]

Yes, I am still thinking about this. Doing away with the dual speed range, I kind of am thinking about making the bike kind of stealthy.

What I am thinking is I could put the LiPo battery in the saddle bag, run the battery wires down the seat post with a connector at the bottom of the seat post. Collapsing the seat post would make it easy to unplug the batteries at that point and just pull the seat and batteries out to take them inside.

The controller would mount behind the seat tube, and the motor would be a Q100 rear hub. Throttle wires would be a bit of black extension cord that at a glance would look like just another brake cable. I considered using a PAS for speed control, to not have to run wires to the front, but from what I read they leave a lot to be desired.

I really do not need to "steaIth" the bike, but I think this would make a very neat installation. On the other hand it would add a couple of pounds to the overall weight, and to the rear which this bike does not need. Mounting everything on the front still makes the most sense. Another 8-10 pounds up there would help the handling. I have also thought about cutting an access hole in the hinge plate and stuffing the batteries into the down tube. I am beginning to think that figuring out what you want to do is more fun than riding the bike will be.

Anyway, I do not have to firm up my plans until after the end of the year. I guess I now need to do some research on just what I am going to need in the way of wiring and connectors.

BTW, The photo shows the bike and the old man (me) who is going to be using it. The basic idea has not changed, I still want a bicycle that give me some cheap short range mobility that I do not really have at that moment.

 

[Jeremy Harris]

I'm a firm believer in making ebikes stealthy, have been from the off. My latest build now has the small Q100 motor in the back, but will shortly switch to having one of the new Tongxin motors in the front. Here's a photo of it with the larger BPM motor in the back, as I originally built it:

It now looks a lot less conspicuous with the Q100, the only thing about that motor I don't like is the noise. It's noisier than the Bafang SWXH motor that I have on my other, fairly stealthy, folder:

 

[cwah]

Why do you want to switch it to the tongxin? Is it because of the noise?

 

[graywolf]

Here it is 4 months later, and I still am not sure what I am going to do. I kind of went from the electric motor to a Chinese motor scooter to a real motorcycle in my mind while waiting on my finances to improve. The motorcycle I was looking at sold a couple of weeks back, and now I am wondering whether to look for another motorcycle, or just order the motor for the bicycle. Finances were holding me back up til now.