20" Folding bike disadvantages/advantages

General Discussion about electric bicycles.
desertcodfish   1 mW

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20" Folding bike disadvantages/advantages

Post by desertcodfish » Nov 02 2013 9:45pm

Is there any downside to buying a folding electric bike?
I read online that the efficiency is exactly the same for a 20 inch wheel as a 27" wheel.
Do you guys think that's true?
I'm 6 feet tall. Does that height preclude me from using a 20 inch wheel bike?
There are some extremely light weight aluminum folders made... about 23 lbs excluding the battery and motor.

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Re: 20" Folding bike disadvantages/advantages

Post by chvidgov.bc.ca » Nov 02 2013 11:47pm

Nothing wrong with folder conversions as ebikes. 20" wheels need faster motors (more RPM/Volt) to compensate for the reduced wheel circumference, if you want to go faster than 20 mph. Its often a challenge to increase the gear inches on the drive train so you can assist meaningfully over 20mph as well, usually needing a 52 (or higher) tooth ring on the front, and an 11 tooth freewheel on the back, which are of lower quality as Shimano doesn't make them anymore (if you do a rear conversion that is). Its probably better to do a front conversion so you can use an 11 tooth cassette, not needing to replace to a low quality DNP freewheel (unless you use the new BPM CST model, which is cassette type rear motor). If you do a front, Dahons and many other folders have spacing issues, not using the normal 100mm spacing that most front motors are designed for (there is the Cute85 as I dimly recall, which is ok for 80mm spacing on Dahons). So there are some issues with folders, mostly related to spacing and gearing. Otherwise go for it - I like my non-folding Cannondale Hooligan with the front Cute 100 motor on it, which is a nice light freewheeling motor with lots of torque and assist to maybe 22mph in the "328" RPM version. I wouldn't recommend the Crystalyte 209 hub motor, designed for folders. I found it to be very coggy, although very fast. Also can be problems finding very long seat posts, for me - I'm 6 feet tall and like to ride very small bikes.

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dogman dan   100 GW

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Re: 20" Folding bike disadvantages/advantages

Post by dogman dan » Nov 03 2013 6:50am

23 pounds is nice and light. but then if you add 10-15 pounds of motor and 10-15 pounds of battery it's now 40-50 pounds of bike.

Still possible to lift into a car, but a bit heavy for more than one flight of stairs.

Why exactly do you need it to fold? To go on the train or something? 20" wheels are preferred by many here, but it's not only on folders that you get them.

As for efficiency, each size wheel can be inefficient when going from 0-15 mph, depending on how well you match the motor rpm with the wheel size. But it's a hell of a lot harder to make the inefficient choice with a small wheel. Once cruising at top speed, both will be approximately the same. But one rule of efficiency remains, faster is less efficient. So to compare efficiency, you have to cruise the same speed with both.

What really affects efficiency is the air drag of the bike and rider. Low recumbents rule over tall bikes for that.

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MadRhino   100 GW

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Re: 20" Folding bike disadvantages/advantages

Post by MadRhino » Nov 03 2013 12:16pm

The only advantage of a folder, is that it folds :wink:
Make it fool-proof, and I will make a better fool.

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Re: 20" Folding bike disadvantages/advantages

Post by Drunkskunk » Nov 03 2013 12:40pm

MadRhino wrote:The only advantage of a folder, is that it folds :wink:
Making them easier to fit in the dumpster :D

Seriously though, Madrhino is right. their only advantage is their size for storage and transport. everything else about them is a compromise. They aren't even that light.
For example, a Trek Remedy Full suspension 27.5" wheeled mountian bike weighs just 28lbs. example here A conventional non suspension 26" wheeled bike can weigh a lot less.
By the time you add a motor, controler, battery, and some form of rack or mount to the bike, you're going to have a heavy bike. A 5-10lbs difference wouldn't be noticable on a fully built Ebike.

As for aerodynamics, the folding bike it's self might be better than a taller bike, but the upright riding position makes the total rider/bike combo as bad or worse than a mountian bike.
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Re: 20" Folding bike disadvantages/advantages

Post by desertcodfish » Nov 03 2013 11:47pm

The trek is way over budget for me. The light weight and low cost of a folder that I can convert to electric needs to be
around $1000.00 to 1400.00 with everything. I need it to be lightweight enough and compact enough to throw it
in the back of my Ford f150 pickup cause I have too many loose dogs in my neighborhood to ride near home.
Would a birdy make a decent conversion? I don't need high speed, I'm just joyriding.
Do they make any kits for little lightweight folding bikes under $1400.00 total cost?

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Re: 20" Folding bike disadvantages/advantages

Post by d8veh » Nov 04 2013 4:46am

If you need a lightweight transportable electric bike, a converted or ready-made 20" folding bike can be a good solution. They'll never handle like a bigger wheeled bike, but they can still give you a decent enough ride.

If you want to convert, you have to be mindful of the folding mechanism, which might limit where you can fit the motor and battery. The forks are normally too narrow for a powerful motor, which means you need a Keyde, Tongxin or Q85 motor. There's also a narrow Crystalite if you can find one. The back-ends tend to be standard width, so you have a wider choice of motors, but you won't want a heavy one if you plan to fold and transport the bike.

You can make a nice conversion using a high end Dahon with a 328 rpm Q100C motor in the back and a bottle battery with integrated controller mounted on top of the frame using the bottle fixings. The battery is then very quick and easy to remove, leaving the bike at about a manageable 15kg or less for lifting. Top speed will be about 30 km/h,but climbing is still reasonable.

One big advantage of folders like the Dahon if you have to keep them in a confined space like a flat, hallway or passageway, is that in a few seconds you can fold the handlebars and pedals flat and park it hard up against a wall. Many members will relate to this advantage.

My Dahon has a 24v Q100 rear motor, 12S lipos in a frog case and 17 amp controller,which gives about 35 km/h and it pulls very hard in the mid-range. I'll be changing it shortly to the Q100C and bottle battery mentioned above.

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Re: 20" Folding bike disadvantages/advantages

Post by -dg » Nov 04 2013 5:23am

desertcodfish wrote:The trek is way over budget for me. The light weight and low cost of a folder that I can convert to electric needs to be
around $1000.00 to 1400.00 with everything. I need it to be lightweight enough and compact enough to throw it
in the back of my Ford f150 pickup cause I have too many loose dogs in my neighborhood to ride near home.
Would a birdy make a decent conversion? I don't need high speed, I'm just joyriding.
Do they make any kits for little lightweight folding bikes under $1400.00 total cost?
I'd suggest the Xootr Swift. They don't fold as small as the Dahon but they ride way better (I've owned both). The Swift is the only folder I tried that is rigid enough to feel like a normal bike. I built mine up with a Bafang SWXU in the front and 14s 5Ah lipo. I get 18+ mph and 12+ miles range depending on how much I help. The motor and battery add just under 10lbs to the overall weight which is less than 40lbs.

II was trying to keep it light, but if I was doing it over I'd accept another pound and use the Bafang SWXK instead. The SWXU is adequate even though I weigh over 250 and need to climb a 9% grade to get to my house. But the SWXK is much stronger and only a little heavier.

A nice thing about the Swift is that except for the stem and seatpost it uses all standard bike parts, no funny narrow forks and hubs, no proprietary anything. And it has steel forks so a front drive is no hassle. One of these days I should do a build thread.
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dogman dan   100 GW

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Re: 20" Folding bike disadvantages/advantages

Post by dogman dan » Nov 04 2013 7:32am

Well, there you have it, Has to fold small enough to fit in a pickup.

Build yourself a light bike, but forget the folding bullshit.

And if you have a truck, you just haven't lived till you have one with a lift gate. 8) Get a ramp, and just ride the thing into the truck is another option.

Last option, build a bike that outruns the dogs, then chase them anyway. Teach them damn dogs to run from YOU!

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Re: 20" Folding bike disadvantages/advantages

Post by slacker » Nov 04 2013 7:43pm

nycewheels.com sell's a tern link d8 folding bike with bionx kit for 2150 i believe.rode a bionx bike a few year's back and if you like to pedal it is a nice kit.very propariaty though.still look's like a fun bike if you require folding and electric assist.jmo.

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Re: 20" Folding bike disadvantages/advantages

Post by desertcodfish » Nov 04 2013 8:25pm

Thanks for all the input.
I really like the Dahon. That' pretty much perfect for my needs.
How much is that Dahon out the door If I buy it new? Including motor and Battery?
Cool bike. Is it for sale?

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Re: 20" Folding bike disadvantages/advantages

Post by MattyCiii » Nov 04 2013 8:37pm

I used a Dahon JetStream as the basis for my first e-bike: http://endless-sphere.com/forums/viewto ... 00#p735620

I started riding folders because it's the loophole for the commuter train around here - no bikes allowed, except folding bikes. I added the electric drive after I got all the conductors used to seeing me and my bike.

The down side - this bike can't take the added stress of the extra weight and speed of the e-drive. I've had to rebuild the front linkage suspension already after about 1.5 years of use, and it's in need of another rebuild. The original wheels and brakes are long gone too.

To go with this bike I'd recommend keeping your power and weight low.
1st build: Dahon Jetstream folding bike. Quick, reliable, capable of 32mph. Light enough to lift, folds for easy transport by car/bus/train.
2nd build: RC powered 2009 Norco A-Line. Top speed 39mph. Built like a tank, it's resistant to Boston potholes, can stop on a dime, easily goes up/down curbs when necessary.

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Re: 20" Folding bike disadvantages/advantages

Post by mwkeefer » Nov 05 2013 12:47am

Have a look at the Downtube.com Nova line, they begin at 24 lbs with all the BS (bell, etc) are really clean folders and are cheap at 299.99

Add to that a 750w Bafang Bottom Bracket Crank Drive and 48v solid power source (25A continuous) and you have a winner, climbs mountains like a billie goat and tops out at 48 on flats at about 27 mph assuming 48t of the Bafang and 13t rear, faster with an 11t 7 speed freewheel.

If you need to go faster, I suggest looking at 15S Lipo or 55.5v nominal - I can climb monster hills in second gear at about 18 mph from a stop and still achieve 32 mph with a 13t (more rear chain wrap than 11) - Same would be good for approx. 35-38 if run with 11t in the rear at the 15S voltage.

The nova is a great bike to start with for a folder the one requirement is to replace the Kenda Tires with something that has Kevlar belting like Schwalbe Marathon Plus or Primo Comets depending on the tire profile you want.

I take mine on the train all the time, in cabs, etc. With 15S2P I have a rough Maximum Speed Range of about 14 miles but if I pedal start then ease into the speed (known as riding conservative) I can get easily 20 miles range from a 10AH pack @ 8lbs - carry a fast bulk charger with you and your range is endless.

I will post some pics tomorrow if you like, I haven't had time to take any good pics yet (and I have a tire to change)...

I'm 6'1" and 168 lbs BTW.

Hope it helps!

Mike
Regards,
Mike

{My Rides]
2010 Dahon Jack - GNG v1 - LYEN 6FET - 20/40A - 18S2P10AH - Nom:66.6v,1332w
2004 Hard Rock Pro Disc - Recumpence ms eDrive v4 - Astro 3220 4T - 12S2P16AH - HV110 - Left Side Drive - Gearing: 38mph
Nominal Peak Power @ 60 seconds: 5328 watts - Maximum Power: 49.8v, 120A, 5872w
2010 Downtube 8FH - Stock GNG v1 Stock Controller - EB809XC - 12-16S
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Re: 20" Folding bike disadvantages/advantages

Post by middriveebike » Nov 05 2013 11:02am

The question is , after you do the conversion, is the bike still foldable?

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Re: 20" Folding bike disadvantages/advantages

Post by desertcodfish » Nov 05 2013 4:37pm

Having a folding bike is not critically important. Having a lightweight aluminum frame with an electric assist is important.
High speed is not important (to me).
I take my bikes camping so I need a bike that is easily transportable. I also tow a small camper so
I can't ride the bike up ramps into the truck.
I am teaching the dogs in my neighborhood to FEAR me. I carry pepper spray and I'm not sparing with it.
If a dog chases me I do use it. I don't care what the owner thinks. If a dog is loose chasing bikes he needs to get sprayed.

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Re: 20" Folding bike disadvantages/advantages

Post by chvidgov.bc.ca » Nov 05 2013 4:47pm

This bike is cool. If you can find one...Cannondale Hooligan. Recumpence would agree.

http://cdn.shopify.com/s/files/1/0247/9 ... 3.jpg?5782

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mwkeefer   10 MW

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Re: 20" Folding bike disadvantages/advantages

Post by mwkeefer » Nov 05 2013 5:36pm

middriveebike wrote:The question is , after you do the conversion, is the bike still foldable?
yep still folds perfectly, and hardly visible.

Mike
Regards,
Mike

{My Rides]
2010 Dahon Jack - GNG v1 - LYEN 6FET - 20/40A - 18S2P10AH - Nom:66.6v,1332w
2004 Hard Rock Pro Disc - Recumpence ms eDrive v4 - Astro 3220 4T - 12S2P16AH - HV110 - Left Side Drive - Gearing: 38mph
Nominal Peak Power @ 60 seconds: 5328 watts - Maximum Power: 49.8v, 120A, 5872w
2010 Downtube 8FH - Stock GNG v1 Stock Controller - EB809XC - 12-16S
2012 Downtube Nova 7spd - Stock GNG v2 - 12S2P10AH - EB809 - 12S-16S - 20A/30A,Nom VCC: 44.4, 888w

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Re: 20" Folding bike disadvantages/advantages

Post by Ypedal » Nov 05 2013 5:47pm

desertcodfish wrote:... I don't care what the owner thinks. If a dog is loose chasing bikes he needs to get sprayed.
I would suggest spraying the dog owner instead.
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Re: 20" Folding bike disadvantages/advantages

Post by desertcodfish » Nov 05 2013 10:21pm

I would absolutely love to spray the dog owners instead but that tends to get costly with lawyers
and court fees :)
I totally agree though that dog owners are the real problem here. Nothing against responsible dog owners.

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Re: 20" Folding bike disadvantages/advantages

Post by dogman dan » Nov 06 2013 6:19am

Right on. I'm a real dog lover, but once a dog chases me it gets taught a lesson. Mostly just outrun, then turn and chase them home. Many dogs learn to recognize me, and start to chase but break off when they see it's me. One dog, or at most two. I'm not that stupid. Any strange dog actually attacks me will get it's ass kicked real good.

Yeah, once you have the camper or boat attached, it gets a lot harder to use a ramp. But it should not be hard to put a 75 pound ebike in the truck one way or another. Place it across the trailer tounge, then stand on the tail gate and lift.

I'm notoriously dumb, but how does folding the bike make it lighter? Seems to me like any decent alloy frame will lift into the truck just as easy. Lighten it by removing the battery, and choose a relatively light motor.

I'm all for the idea of taking the bike to a great place to ride. I do it all I can. I have a hitch rack for the Subaru, or if taking the longtail I have a small trailer to carry it. I have to camp in the back of the car, but that's fine for one night.

If the trailer is pretty good size, maybe you can just put the bike inside it for the trip? If you must, remove the front wheel to turn the bars and get through the door. If too long, stand it on the rear wheel to make it short to maneuver into the trailer.

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Re: 20" Folding bike disadvantages/advantages

Post by MadRhino » Nov 06 2013 10:07am

Last week a dog started chasing us when we crossed a girl with her two dogs in the mountain trail. I said to my fellow rider not to bother and keep going, and the dog followed us about a mile. The hassle of finding her dog in the mountain was a lesson enough for the owner. Last year I crashed because of a dog jumping in front of my wheel. Now I don't try to save them anymore, if it gets on my way I ride on it and if it is chasing me I will bring it as far as I can from its owner.
Make it fool-proof, and I will make a better fool.

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Re: 20" Folding bike disadvantages/advantages

Post by desertcodfish » Nov 06 2013 1:02pm

Answer to " how does folding bike make it lighter"?
Are there any bikes out there under 25 lbs that aren't over $1000.00?
The folding part doesn't make it lighter
but I don't think (correct me if I'm wrong) you can get a non-folder lightweight for under a grand.
Like I said the folder isn't a necessity.... Lightweight and under 1400 bucks is.
I've seen lightweight (under 25lbs) folders for less than $800.00
I know everybody has different definition of lightweight. That is my definition.
The lightest e-bike in the world is around 16.9 lbs.

My trailer is 5x8 inside but once I've got the queen bed and AC inside there isn't room for a bike.
I'm thinking of maybe using a front hitch on the 2012 ford f150.
Or a hitch doubler with bike rack, that I can squeeze the bike tween the truck and trailer (YIKES).
The truck bed is too full of camping necessities like generator, coolers, etc for a full size bike.
The truck bed is a little on the small side.

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Re: 20" Folding bike disadvantages/advantages

Post by cal3thousand » Nov 06 2013 2:09pm

Sounds like you're just using the bike to get around the local campgrounds. Folder will be just fine.

If you're looking for a bike to take into the trails, that's a different story. But just putt-ing around the camp, you don't need more than a cheap folder. You're not using this as a commuter
Get a Cycle Analyst and a Multimeter, you're still a noob if you don't have at least one of each.

Planning on posting questions or buying anything on this site? Put up your country (at minimum) on your profile. This is a worldwide forum and we haven't reached clairvoyance.

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dogman dan   100 GW

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Re: 20" Folding bike disadvantages/advantages

Post by dogman dan » Nov 06 2013 2:51pm

Well, a very light classic steel road bike weighs 27 pounds. Last one I bought was ten bucks. That was years ago, but I see them from time to time in unrestored condition for $50-150. But it's far from small and easy to throw in the truck as a 20" bmx bike. I was thinking more along those lines than folders. I'm not sure what a steel bmx weighs, but I doubt it's more than 30 pounds. A steel 26" mtb might weigh 30-35 pounds.

I get it that if you add ten pounds, doing a clean and jerk lift of the bike to get it aboard is much easier with 30 pounds than it is with 40. So starting with lighter is a benefit. Some folders have very tiny wheels that do make them lighter. I just meant that a bmx might be light enough, and cheap.

Kiss light goodbye when you bolt on a medium strong hubmotor. But there are very light ebikes using a friction drive. The smaller gearmotors are less than the 15 pound weight of typical ebike hubmotors, with tire. I think a 20" bike of any kind, with a low wattage gearmotor should be as light as is practically possible without going to a friction drive on a pricy carbon bike.

I would definitely consider rigging a front bumper mounted hitch reciever, likely a homebrewed thing, then add a swagman bike rack. No need to make it strong enough to tow, just able to support 200 pounds or so. The kind that supports the bike at the wheels. Then you carry the bike up front, and it's quite easy to load up a 100 pound ebike or two.

Or similarly, a bike rack or cargo tray added to the trailer.

Or maybe you just need to rig a step of some kind on the trailer tounge, so you only lift the bike up to the bed from the tounge, rather than trying to go over the truck side.

Another thing possibly worth looking at, are small step stool like devices used by sheetrockers. Looking like a cross between a sawhorse and a bench seat, you'd place the bike on that, then get in the truck, and lift over the side.

I agree, you don't want a 100 pound ebike, but there are many ways to get a 60 pound ebike aboard easy.

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Re: 20" Folding bike disadvantages/advantages

Post by desertcodfish » Nov 06 2013 4:58pm

Can a six foot 190lb male ride a bmx comfortably?

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