Adding a 3-speed internal hub
 

I've a couple of Dahon Mariner D7's. Great bikes, but a little more gearing would make climbing easier. I'm considering adding 3-speed internals to mimic a triple chain ring. I'm sure it's been done, so I'm looking for a bit of guidance. Any help or suggestions are appreciated.

you mean a dual drive ? Cassette + a IGH ; or just a 3 speed IGH ?

dual drive hubs require a 135 wide rear dropout frame. 3 speeds are available with shorter axle versions.

For Brompton Etc. they S-A make them in a sub 120mm width.

Sorry, Bob. I'm talking about a dual drive setup. Right now the Mariner has a 7-speed cassette.

You can fit a 7 speed hub in a 126 wide dropout spread, as I said the Dual drives require a 135 wide rear frame spread

Perhaps you can measure that? the inside the dropout faces width is the place to measure .

& just because it has 7 speeds does not mean it is a cassette , many make that assumption, falsely.


Sachs used to make a 7 by 3 hub, after the SRAM Buyout they no longer do .. its 8+..

Are these silver (brushed aluminum) with 20" wheels?

-HANK RYAN-
Norman, Oklahoma USA

Yes, they are.

Yep, the SRAM DD24-27-30.

The Sturmey-Archer CS-RF3 hub is nominally 135mm OLD, but I think the 6.8mm lock nut on the non-drive side could be either replaced with a thinner one or left out all together (there are three lock nuts there, after all) and the wheel built with more dish.

The Dahon Mariner D7 that we currently have in stock is 135mm OLD by my measurement (without removing the wheel). We recently upgraded a Mu P8 to a DualDrive with an 8-speed cassette. Here's a list of the items for the Mu upgrade:

20" wheel with DualDrive hub (built by Quality Bicycle Products)
DualDrive 8-3 shifter
DualDrive click box
X4 8-speed rear derailleur
Derailleur Hanger (to accommodate a standard rear derailleur on the Mu - this might not be possible with the Mariner)
Housing for gear cables (~9')

Expect to pay $450-$600 for a local bike shop to do this upgrade.

-HANK RYAN-
Norman, Oklahoma USA

I think you'd be better off selling your current bike and buying a Dahon Vitesse or Novara Flyby that comes with an IGH.

That's the conclusion I'm coming to, Cyclosaurus. Using Hank's numbers and prices found on Amazon for the Dahon Mu P24, as long as I can sell my bike(s) for at least $160 each (and I'm fairly certain I could bet more), I'd come out ahead.

That being said, I may spend some scrounge time at the local bike co-op and see what I can come up with.

FWIW, my understanding is that the Mu P24 has been replaced by the Mu P27, and neither model is currently available in the USA from Dahon. But some of them are likely still available at authorized dealers and other resellers. And I would consider a used bike if it has been well-kept. Keep in mind that the Dahon warranty only applies to bikes that are purchased new from an authorized Dahon dealer, and the warranty is not transferrable to a subsequent owner. I agree that looking for a Mu P24 or P27 (new or used) is a better plan than attempting to upgrade your Mariners.

-HANK RYAN-
Norman, Oklahoma USA

might wanna check my garage sale area .. I have a vector with dualdrive .... and some nice mods on that bike as well. Might fit the bill
seems that all other 24 dual drive bikes are sold out this might help you

Best Thor