Folding Bikes - Modding an Avenir single speed

I just bought an Avenir folding bike from ebay for $120 for a bad weather back up bike, I believe this is a Dahon rebrand for Raleigh. It's a single speed and I want to convert it to a 5 or 8 speed internal hub or a 7 or 8 speed casette. Does anybody know what the best option would be for this or if it is even possible?

Here's the pics:

http://akamai.edeal.com/images/catalog1802/folder64398/img5817720.jpg

http://akamai.edeal.com/images/catalog1802/folder64398/img5817717.jpg

http://akamai.edeal.com/images/catalog1802/folder64398/img5817718.jpg

I'm a little concerned regarding the rear wheel set up. Will it even be possible to fit a casette in there or should I just go with an internal hub shifter?

Opinions?

Thx.

Step 1: Measure the rear wheel over lock nut dimension (OLND). To fit a cassette, it needs to be 130mm or 135mm. You could respace it if it is less, it looks like a steel frame.

I recommend an 8sp hub, it would be easiest since it has horizontal track ends. Even 5sp should be fine for bad weather since you would be going slow anyway. Hub gears are better for bad weather.

Hey! I was gonna' bid on that one, too. But I forgot to look late in the game. I probably would have left it as a single-speed, lowering the gearing and making a few 'cab' modifications.

Good luck with the mods!

Thanks, Now I have to keep my eyes open for some parts. I'm leaning towards the Nexus 8 speed internal hub route, I saw one on ebay that was listed as "from a recumbant". Is there a difference? With the 8 speed I figure I could have a spare bike for my gf or my daughter to ride as well.

Does anyone know anything about these bikes? Google has little information. All I can guess is that it is a Dahon made Raleigh. It looks like a Helios but I've read that it's the same as a 2004 Boardwalk or an Impulse. It has a steel frame, which I actually prefer since the aluminum one doesn't really shave off much weight anyway.

EDIT: This frame is the closest I have found to the one in the pictures: http://www.dahon.com/archive/2006/intl/impulsed3d7.htm Others are similar but this one looks the closest and it's steel.

So many people converting multi-speed bikes to single speed and fixed speed and you want to go the other way, even though you have the perfect track-style dropouts! :-)

It used to be that keen cyclists used fixed wheel bikes for winter training. That would be my vote.

Urbane Cyclist sells the Avenir as a 6 speed or single speed. They probably know the history of this bike as well.

It is probably spaced 120mm. Without respacing the frame this limits you to the Sturmey Archer 8sp hub or the SRAM or Sturmey Archer 5sp hubs. The Shimano and SRAM 7, 8, and 9sp hubs are designed for wider OLN spacing.

alex

It is probably spaced 120mm. Without respacing the frame this limits you to the Sturmey Archer 8sp hub or the SRAM or Sturmey Archer 5sp hubs. The Shimano and SRAM 7, 8, and 9sp hubs are designed for wider OLN spacing.

alex

I'm concerned about that, I did notice that they Avenir also makes a 6 speed casette version with the steel frame. I'm thinking that may mean the spacing is a bit more than 120. I guess I'll find out when I pick the bike up on Thursday. Either way, an SA 8 speed or SRAM 5 speed isn't the end of the world.

So I picked it up last night. It's in pretty good shape for a police auction bike, needs a bit of a tune up but that's about it. One thing I'll mention about Avenir - cheap ass components. Really cheap. Other than that it rides well. My girlfriend who's been a nay sayer on the whole folding bike thing was suprised at how well it rides. It doesn't really fit me well but then again, I'm 6'3".

Now the nitty gritty. The rear wheel Over Locknut Dimension looks like it's just a hair under 110 mm (rough measurement). This is going to limit my options for internal hub. I was hoping for the Shimano Nexus 8 speed but it looks like that'll be out of the question. The Sturmey Archer X-RF8 has an OLN dimension of 116 mm so I guess that's a maybe. The X-RF5 has an OLN dimension of 113.7 mm so it's probably a better bet for fit. And, of course there's the SA AW 3 speed. It has an OLN dimension of 107.7 which is pretty much a perfect fit.

Looking at the chain ring it had 52 stamped on it so I'm guesing it has 52 teeth. Does that sound right? Using Sheldon Brown's (http://www.sheldonbrown.com/gears/internal.html) gear inch calculator I can get the following:

Sturmey Archer AW 3 speed:

With a 18T rear sprocket I'd get a range of 43.3" to 77" Not too bad I suppose.

Sturmey Archer X-RF5:

With a 17T rear sprocket I'd get a range of 38.1" to 85.7"
With a 15T rear sprocket I'd get a range of 43.2" to 97.1"


Sturmey Archer 8 speed might be geared a tad bit high:

With a 23T rear sprocket I'd get 45.2" to 137.9".
With a 25T rear sprocket I'd get 41.6" to 126.9".

On my Cannondale Bad Boy I usually use the middle chain ring which has a range of about 28" to 86" so I'm thinking the 5 speed may be the way to go. Does anyone know the OLN dimensions for the SRAMs or Shimanos?