Which engines fit the Birdy?

[Arbol]

Even though there is an electric Birdy, it seems to make sense to add a kit to a non-electric Birdy, since the price of the electric Birdy is quite high.

http://issuu.com/kooskroon/docs/birdy_katalog_2012?e=4492709/2612960

Do you know which engines would fit the non-electric Birdy?

I do not know the size available for an engine front and back of the Birdy (but the engine in the electric Birdy is back, so probably it makes sense to put it there).

I guess Q85 would fit, but what about Q100, BPM or MAC?

 

[DAND214]

ENGINE? Small block Chevy?

Or do you mean Motor? Mac, crylte and so.

Very confusing, isn't it?

Dan

 

[Arbol]

Sure, I mean an electric motor, not a combustion engine. Like a 9C, a Crystallyte, etc.

 

[spinningmagnets]

It's an 18-inch wheeled folding bike. Interesting front suspension linkage.

 

[dogman dan]

The main thing would be finding the motor with a dropout fit that matches your folder.

Many of the folders have less than 135mm dropouts in the rear, and less than 100mm front. So standard bike kits don't fit.

Most likely thing to work, would be to take a standard rear motor, and use a single gear freewheel, which might get you enough space to fit the motor on a narrower rear end.

The smaller diameter hubmotors, typically gearmotors, would be the easiest to lace into an 18" rim.

 

[Arbol]

Thanks. Which are the typical gearmotor models? I understand q85/q100/mxus are gearmotors. BPM and / or MAC too? I assume 9C / Crystallyte are not (they are called direct drive, aren't they?).

 

[footloose]

I met a local rider who has a Birdy with Bionx rear wheel. Talked with her briefly-- she loves the setup. I think the Bionx hub fits a standard dropout dimension (check e on this, I'm not certain about it). If it does... Implies you could use any other standard motor at least for rear wheel.

 

[Arbol]

I met a local rider who has a Birdy with Bionx rear wheel. Talked with her briefly-- she loves the setup. I think the Bionx hub fits a standard dropout dimension (check e on this, I'm not certain about it). If it does... Implies you could use any other standard motor at least for rear wheel.

Does anybody know if this has been tried, or how could I know for sure? I am interested in the Birdy, since it is unique: foldable but able to cope with (good) non-tarmac paths.

 

[jateureka]

from the Bafang crank drive thread...

...Well, I have two concerns, one general and another one more specific:

- The general is that of course I am used to 3 chainrings. In steep hills, I often need to use the "nanny gear" otherwise I need to get out of the bike. I am concerned with only one chainring, I either risk being unable to climb steep hills if my battery is down (if chainring has too many teeth) or that I will not be able to enjoy full speed biking if the chainring is too small
- The specific is that one of the bikes I am considering is the Birdy. In fact, I opened a post on this bike http://endless-sphere.com/forums/viewtopic.php?f=7&t=52092 but it did not get traction. The Birdy is foldable but apparently more resistant than say a Brompton. With so many burglars in my city, it seems a foldable makes sense. There is a Birdy with a motor, but it is too expensive. I see locally a second hand Birdy, but the basic model, the Europe, with only one chainring of 56T and 8-speed Shimano, 11T-30T http://evobike.hu/termekek/nev/Birdy-Europe/termek/1148/lang/english

The issue is that it seems 56T is a bit odd, and probably the Bafang crankset is not 56T, altering the gears of the bike. That may be, or may not be, a problem. But I was wondering if one could keep the existing crankset and not using Bafang's crankset.

The Birdy seems ideal to use the BBS-01, I do not know if it has enough clearance / space to fit it in.

http://www.birdybike.com/?Home

18" wheels are not a very common size, so this means an uncommon 56T chainring size also to get 'standard' gearing.

 

[d8veh]

As far as I can figure out, the Birdy has standard width rear drop-outs, so you can use any motor in the back, but you'll need to think about where to fit the battery and controller. Make sure you buy a Birdy with derailleur gears not the Sram dual drive. The 238 rpm Q140 motor with cassette spline would make a good candidate for 18 mph max, or you need to go up to 12S lipos for 22mph, which is about the safe limit for the motor.
http://www.elifebike.com/peng/iview.asp?KeyID=dtpic-2013-46-K3QJ.1WASD
There's also a splined MXUS, like the one I'm selling, that would do it if you want a bit more power. It would give 14 mph at 36v and 19 mph at 48v in 18" wheels:
http://www.ebay.co.uk/itm/181187625644?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649

 

[Arbol]

There's also a splined MXUS, like the one I'm selling, that would do it if you want a bit more power. It would give 14 mph at 36v and 19 mph at 48v in 18" wheels:
http://www.ebay.co.uk/itm/181187625644?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649

Mmm the MXUS seems really nice. But the external label says 350W right, not 250W?

I see you have used it up to 48V and 22A. The 22A were also with the 48V, or did you reduce amperage when at 48V?

The battery would be fitted in a front bag, as for the Birdy Hybrid. I do not know yet about the controller.

BTW, you do not include the Bafang CST 250W into the possible options. Is there a reason for that?

 

[d8veh]

The MXUS motors I have don't have any power markings, so you can add your own. I am presently using a 22 amp controller and the motor is very smooth. I also tried it with the same controlller but with 12S lipos charged to 50v. They made it feel like it was working harder but of course performance was much better.

I didn't recommend the 250w Bafang CST because it's a lot bigger and heavier. Also, it won't spin fast enough unless you go to high voltage.

 

[DIY_turbo]

How heavy is the MXUS - is it a Bafang clone? How is the freewheeling?

 

[d8veh]

How heavy is the MXUS - is it a Bafang clone? How is the freewheeling?

The MXUS isn't a Bafang clone. There's presently no Bafang that size with a cassette spline. It's a couple of mm bigger than a Bafang SWX, and approximately the same weight.

 

[DIY_turbo]

Hi dv8eh

In one thread you point out that...

I have cassette versions of the 350w MXUS, and to me it looks like they messed up a bit. They included an extra seal over the cassette outboard bearing, but they didn't provide the correct spacer for its inner lip. The resukt is that the seal's lip is trying to seal on the nut that half sticks out of the cassette spline. It caused drag like in your video. Given that these Chinese companies all copy from each other, it might be worth looking at yours in case it's the same. Here's a picture of the seal and the missing spacer (18 x 12 x 3 mm), which I took from a BPM motor. You don't need the seal because the bearing is sealed

Have you resolved this problem, and is the motor that you're selling on ebay fixed? Is their still a drag of anykind affecting the freewheeling?

 

[d8veh]

The seal doesn't do anything and shouldn't be there because the bearing behind it is already sealed. I just hook them out. The Bafang CSTs and the Q140s have the same spline and bearing, but no seal.

There's no drag once the seal's removed.

 

[DIY_turbo]

Thanks dv8eh - you're info is most helpful.

How problematic would it be to put a 10sp cassette on the MXUS?

 

[d8veh]

MXUS state that the spline takes up to 9 spd, but I can't see why a 10 spd won't fit, but it depends on the stack-height and length of thread on the retainer. AFAIK the stack-height of a 10spd is the same a a 9spd. The spline is 35mm long.
http://sheldonbrown.com/k7.html

 

[DIY_turbo]

D8Veh,

Looking for word on getting my new motor. What would the highest voltage that you would run this motor? i intend on using Keplers technique of volting up but amping down as he he mention on his thread,

A few reasons for going with 18S.

Firstly I am big fan of the Volt up Amp down line of thinking. It allows you more kW out for a given size controller and sized cabling. This in turn is conducive to less wasted heated under most conditions.

Consider if I am using say 800W @ 70V to maintain 30mph. In this case I am drawing a tiny 11.5A which is a piece of cake for a 6 FET controller

Could I also go to 70v with the MXUS?

 

[d8veh]

Any motor ca run at 70v. Whether you get any problems depends on the power you put through it. I'm running 36v with 22 amps and it doesn't feel at all stressed, so 70v at 12 amps should be OK. It's rated at 350w continuous, but we know most 250w ones can run at 1000w (from the battery) as long as you're careful, so I'd expect that the MXUS can go a bit higher.