Best folding bike for conversion?

[paull]

I've got a commuter bike based on a 5303 which is serving me well. I'm now wanting to work on something new. For that I thought I might put together a rc motored folding bike for zipping between buildings at work(*). The build being mostly about having fun rather than any real utility

I know I've seen a few folding bikes here (long time lurker). Any opinions on which folding bikes are best for electric conversions?

My plans/requirements:
- I'll just ditch the pedals. No need for "backup" human power since I'll never be that far from some Google building where I could stash the bike.
- Don't need to go very fast but should have plenty of torque
- Plan to use a bike with a geared hub, probably an 8 speed on 20" wheels. I'm hoping to be able to manage a single stage like Gary has done with his 3220 build. The 8spd should help here.
- Plan to use small LiPo battery (12s 5Ah maybe?) since I won't go far between charges.
- I need to be able to fold the thing and carry it up to my second floor office without too much trouble (gotta get some exercise).

I was looking at the Downtube 2008 FH. It has a full suspension and a Sturmey Archer 8 speed hub. The geometry seems pretty good for motor/controller mounting also.
http://www.downtube.com/Full_Suspension_Internal_Hub_Folding_Bike.html

Any opinions?

* We have cheap crappy walmart grade bikes at Google for this purpose but they always seem to be either 50% operational or not where I need them when I need them :-|

 

[paull]

On second look it seems the 8 speed S/A hubs start at 1:1 I guess I really want an Alfine hub which starts at 0.527:1

 

[GGoodrum]

Hi Paul, and welcome.

I like these bikes as conversion candidates, for a couple of reasons. First and foremost is because it doesn't have a bottom chainstay. That makes it easier to fit a larger direct-drive sprocket on the back, and not have chain interference problems. There's also plenty of room between the rear tire and the seat tube/bottom bracket area. It looks like there is a "foot" on the bottom bracket, that is used to support the front of the bike, when folded. My West Marine Port Runner has the same thing. This can be a great place to mount the motor, as you don't have to worry about torque twist. Having the motor low like this also allows larger sprockets to be used without the chain hitting the V-brake mount. The only concern I'd have is about the geometry changes when the rear shock is compressed. You could solve any potential chain stretching/relaxing issue with a spring-loaded tensioner, though.

-- Gary

 

[mwkeefer]

Howdy,

> * We have cheap crappy walmart grade bikes at Google for this purpose but they always seem to be either 50% operational or not where I need them when I need them

Unless I missed somthing you have the alloy versions of the Citizen folding bike available (assuming the multiple references to google buildings and such mean you work for or squat google) so I am curious as to why your interest in the Downtube FS8/9 vs the Citizen?

I hope it's not the obvious answer, that the Citizens are the "walmart grade" bikes you have a Google. Maybe google got you guys good pricing on these but bought cheapie other brands for employee use? Shouldn't all of googles bikes be eBikes? I'll bet you guys would have had the mail request routers up faster than 100 minutes if they were eBikes!!!

Sorry for that one, I had to...

I actually ordered a Citizen Gotham and am planning on going to Downtube in Bensalem PA on Tuesday to pickup a 2009.5 FS9 ( or somthing like it ) with similar final intention as you, RC based drive like the Port Runner (which is way cool) but the first stop will be a 20" hub based on each of them (providing I can make it fit)...

I have to hand it to Yan over at Downtube... I emailed him at 10pm last evening (Holiday weekend, sunday night) expecting to hear back on Tuesday. I stepped outside for a cig and when I came back he had answered all my inquiries about geometry, sizing, weights, optional upgrades, tensile strength (as it relates to using Kevlar belted or run flat tires on his design and the transfer of force to the frame) and all other such things. Apparently he is a professor at Temple (I buzzed by there on my own eBike this past thursday) University amonsgst others and I have to say... that is customer service.

For anyone interested the sizings are:

> Nova has a 130mm fs is 135mm both are standard rear axles. Fronts are 100mm again standard.
> Top speed is around 20 on both but gearing can be swapped. Internal hub bikes have higher gearing.

Not sure what "standard" axle means but ... I also don't care, even if I can wedge a hub motor into one of these... I can and will build a direct drive system with one of the rewound tower-pro 5330s i have laying around here or I will get Matt to make me a tiny single stage reduction unit and drive the rear directly.

Please keep us updated on this build = )

-Mike

 

[mwkeefer]

Update -

I did purchase a FS9 from downtube because they are local and were great when I went to see them and test ride, the things were sweet so I picked one up... Currently it is running 15S lipo on a 20" rear with a single gear freewheel. Its a torque monster running on a simple Infineon stock controller.

I will post build pics / process / troubles and work arounds as I finish the install and make it pretty!

-Mike

 

[paull]

> * We have cheap crappy walmart grade bikes at Google for this purpose but they always seem to be either 50% operational or not where I need them when I need them

Unless I missed somthing you have the alloy versions of the Citizen folding bike available (assuming the multiple references to google buildings and such mean you work for or squat google) so I am curious as to why your interest in the Downtube FS8/9 vs the Citizen?

The citizen bike is available to us at some "reduced" (not really) price but that's not what we have around for us to use on campus. Most of what is there are a bunch of these (yes the ladies version ):
http://www.huffybikes.com/Products/Product.aspx?p=7&cat=5&subcat=17
Between bent pedals and chainguards, loose chains, ... you rarely find one that actually works.

But a few days after I posted they did finally get some special made citizen bikes (non-folding) for us to try out. They are much nicer... But they don't have motors

 

[paull]

I did purchase a FS9 from downtube because they are local and were great when I went to see them and test ride, the things were sweet so I picked one up... Currently it is running 15S lipo on a 20" rear with a single gear freewheel. Its a torque monster running on a simple Infineon stock controller.

I will post build pics / process / troubles and work arounds as I finish the install and make it pretty!

Yes Please!

 

[mwkeefer]

I'm done rough out stage #1 on the FS9 from Downtube... to go electric with rear hub I lost all but a single gear = (

I will post pics and such later this week when stage 2 is done and it's not embarrassing anymore!

-Mike