Originally Posted by
bhtooefr
I'd like to add an IGH of some sort to my Dahon Boardwalk 1, and am considering my options.
So, here's the options I have that I know of:
SRAM Automatix. 28h could be built into my existing rear wheel, but is hard to get in the US. (Or a 36h could maybe be laced for 28h?) And, no matter what I get, speed would need to be adjusted. Also, I'd need to spread the rear triangle from 110 mm to 120 mm. Upside is, automatic shifting and all, no worries about shifting during braking.
Sturmey-Archer S2C. No worries about adjusting the speed, but I hear these have horrendous reliability. And, kick-shift, so it'll be a little awkward to use. 116 mm OLD, so the rear triangle would need to be spread a little, but not as much as for the Automatix.
Find an old Sachs Duomatic. It would have to be disassembled and cleaned, which would be a pain, but could be worth it. Still kick-shift. And, I've read that they're designed to work with 110 mm rear triangles, although it's actually 112 mm OLD.
Find an old Sachs Automatic. Same issues as the Duomatic except automatic (and shift speed would need to be adjusted), and 114 mm OLD.
Go three-speed. Downside is the shifting mechanism is exposed to damage, on a folder, unless I get something with rotary shift. And, controls are less simple.
What's my best bet?
I do have the Sachs Duomatic or known as the S2C and it is on my Speed Duo. It's true that while it does not seem all that reliable to begin with (mine works ok so far after thousands of miles riding in crappy weather), I think the S2C works better in the Low/Med gearing setup rather the typical Med/High setup that most people will be setting it up for. If you set it up for Med/High, you will be immensely disappointed with the S2C. For Med/High gearing, I would recommend that you go with the SRAM Automatix route. The reason I like the Duomatic setup is the control I have speed wise by varying my "cadence" when the gear is fixed. If I go pass a certain speed point, the gear will not shift like the Automatix does on the Tern Verge Duo which I disliked. When you have only 2 speeds, the only way to can fill that void is to vary your cadence to add more speeds to it. For slow speeds and low gearing, I found the Automatix shifting too soon and too often. However, in medium and higher gearing the Automatix works really great. My Duo is used as a coffee bike riding with my partner and her friends and sometimes, it's hard to ride slow with a high cadence on the Automatix. With the S2C, I can spin as fast as I want in low gear and still be on par with them.
Part of the issue with the Sachs Duomatic S2C is that it needs a certain speed for it to shift properly when it ages. Most problematic is when it is shifting from a high gear to 1:1 where it won't most of the time when the wheel spins lower than the speed it needs to shift and it seemed you need to fight the hub to get it to shift. This is its downside.
However, if you set the direct drive to low like around 35-40" gear and the high drive to 50-55" gearing, then the S2C works really well because if it's stuck at 55", just stand up and ride a bit faster to shift down. Whereas with a 70-80" high gear, it takes a bit more effort to reach the same speed to shift and this is when you're going to be fighting with the hub more.
I live in Vancouver where there are tons of hills so the Low-Medium gear setup is better for me, plus riding with my partner slowly helps to stay with her longer on the sea wall without the thing shifting too often and me braking all the time. Braking on the S2C is secure as well and I rarely use the front brake of my Speed Duo unless in heavy traffic.
So with my Speed Duo, I get the same benefit as the Shimano 3 speed coaster hub gearing without the high gearing. Btw, there are 2 folks here who converted their boardwalks to take the Shimano 3 speed hub with good experience. I almost went this route until Bruce Metras offered me the S2C at a really good price I couldn't refuse buying.
The other luxury option is the SRAM P5. It's a 5 speed coaster hub that has everything. Still needs a shifter to shift. I would love to have this, but it's not cheap compared to the S2C or the A2 Automatix.