Murray Missile 

I just pickeed up an old Dahon Stowaway, I'm guessing a late 90's model. It needs some TLC but it should clean up well. I want to make some minor drivetrain upgrades, as found it has a 6 speed Gripshifter, an old very low end Shimano SIS derailleur and a 7 speed freewheel. Seems to have been some skullduggery at some point in the past. I was already planning a 7 speed ugrade so that's a plus but I'd also like to put a better RD on it and replace the gripshifter with a trigger shifter. I understand there is some voodoo involved when selecting a rear derailleur for a 20 inch wheel. Do I need a short, medium or long cage? I have an RSX long cage and a couple Deore LX long cage that are homeless right now, i don't suppose one of those would work?

GeezyRider 

If you have a hook mount that will work with your Dahon, the derailleur cage length shouldn't be an issue. I have a couple of 20" wheel bikes with long cage derailleurs and never had an issue. In fact, I recently upgraded the derailleur on my Zizzo to a Deore long cage.

Murray Missile 

Thank you, I have a pile of claw adapters. I'm going to give a short cage RSX a try first. I haven't counted the teeeth on the freewheel yet but it looks to be spaced fairly close, not a corn cob by any means but the large cog doesn't look to be bigger than a 26. I have pretty long legs so I'm also going to try a 58t chainring. I also have a coaster brake Boardwalk and I always seem to run out of "top end" on it. I think with the 20" wheels I should be able to handle a 58 up front.

I need to pull out my extra brake sets, I have some Tektro 559's I bought that turned out to have too much reach for that project but they may be perfect for this. I also have a pair of 20 X 1.5 Kenda Kwest high pressure tires on the way. I have Kwests in 26 inch and 700c on a couple other bikes and really like the ride. I wanted 1.75 since I'm on the larger side but the Kwests are only available in 1.25 and 1.5 in 20 inch, however they tend to run toward the large side so it should be fine.

Edit: Just got the Boardwalk out to run to the post office after a long winter in storage. It has Kenda Kwest 1.5's but they're only 65 PSI, it also has what appears to be a 48t chain ring and steel crank arms. It will get the aluminum crankset off the Stowaway when I swap it out.

Fentuz

The cage length depends of the number of teeth on the larger cog. Also, the cage length have changed order the years. i found that 90’s/2000’s long cage are pretty much nowadays medium cage.

I run sora short cage rated for 30teeth max with a 11-36 9 speed cassette. The sora derailleur has the same length as altus m310 rated for 32 T (fitted on dahon dash 20”, frog 20”). I run m310 with a 11-36 9speed cassette and acera 9 speed shifter on my daughter frog 52 (20”).
I would not want to run a longer cage as this one can touch the ground when i do light single track.

The bottom pulley doesn’t go lower than the wheel rim so ~3” from the ground.

i built a hammerhead with a 7speed 11-30 and used the m310 derailleur with a alivio 7 speed shifter and a 7/8speed kmc chain.
it worked well, shifting is nice and crisp. IMO, It was a good choice for a cheap and low maintenance setup.

GeezyRider 

This is good info, thanks for sharing it. Assuming he is keeping the existing freewheel and chainring, do you think the OP can make either of the two long cage derailleurs he has available work for what he wants to do with his Dahon?

PS: I really like what you have done with your Dahon builds.

rhenning

I bought a Dahon Board walk for $50 as a project and a few weeks later was given one that is basically the same. Drive train is basically 7 speed Shimano and seems to work good on both. Roger

Murray Missile 

OP here, since the roads around here aren't the best I opted for an RSX short cage to give me more clearance. If I do switch freewheels I probably won't go bigger than the current 26t on the large cog but the one that's on it feels good, it's pretty grimy so I won't know what it is until I tear the bike down for overhaul. I'll be changing the crankset eventually but I'll see how the original works first before I buy a chainwheel, the original at least has aluminum arms. I have a large storage tub full of derailleurs but most are long cage and the SIS compatible short cage I have are dedicated to current builds. Most are Shimano 105 and 600. but I'm not above putting lipstick on a pig as they say. I put full Deore XT 3 X 9 with XT V-brakes on a 1997 TREK 820 but I bought the bike new and it's one of the last USA made 820 frames, lots of nostalgia with that one. It's the bike that got me back into cycling after many years away from it. When all my bikes get sold off someday it will be the last to go.

I have an Alivio 7 speed trigger shifter on it's way now, I need to dig out those Tektro brakes today and see if they'll work.

If Accushift 7 speed freewheels weren't made of gold I'd put a short cage Cyclone on it, I have a NOS set of Suntour 3 X 7 Accushift twist shifters........

GeezyRider 

Sounds good. Glad you got it sorted out. I've put so much lipstick on pigs I should buy stock in Revlon!

Murray Missile 

Beats wrestlin' in the mud with 'em LOL. Dug those Tektro 559's out, perfect fit! She's gonna be the fanciest Dahon in town. Of course there's only 2 and I own both of them.

Fentuz

i think the hangar is bit long but, it might work. As the OP is not going for anything bigger than 26T, a short cage is more than suitable.
personally for $100max, I’d fit a 14-34 or a 14-28 speed free wheel, alivio shifter and a m310 derailleur…

i have a serious illness called “pimp my ride” 😅

Murray Missile 

Hosed the big chunks off it today, aired up the seriously rotted DURO tires and took it for a spin. Even with gaping crevices in the tread and sidewalls it handled quite nicely. It feels much more solid than my Boardwalk, is that just me or is there something to it? They have the RD set so it shifts from the smallest cog to the next to biggest and the shifter is about ready to buy the farm, very "notchy". The shifter has a full gear worth of travel beyond 6th gear, they could have set it so 6th at the rear was in that overlap and 1st on the shifter would have been able to reach the big cog. Moot point now though, the shifter's on it's way out and a trigger shifter is on it's way. It has a 52t chainring, at the back end I may be off on my 26t big cog guess, could be bigger, no markings on the freewheel that I can see but it feels good so whatever it is it stays. Brake pads are fossilized, getting it stopped was a close one eye, pucker up and hope for the best experience.

Fentuz

It has a more conventional diamond frame; the boardwalk is a "single beam" which will flex more.

Murray Missile 

I kind of suspected that but wasn't sure if was just my imagination. I had wanted a multi-speed Boardwalk to go with my single but after riding the Stowaway I prefer it even though it also feels a bit heavier than the Boardwalk. I can probably shave an ounce or two off it though. Wish you could change handlebars. I think Trekking bars would be great on these.

Jeledoux

I just picked up a Stowaway from a neighbor who was going to throw it in the trash. He didn't have a manual. I think I have the same bike as you do. Can you tell me where to find a manual?