Folding Bikes - What are the advantages of a derailleur folder? Why are they marketed?

If i were going for a cheaper sortoff alternative to the Rohloff i'd go for a 7 speeds hub plus Speeddrive or possibly a Dual Drive.

Agree. 100% satisfied with my SRAM Dual Drive for now. Rohloff would be the next step up if the number/frequency of international flights increase in my life. For now, having my bike fitting inside my trunk under 30 seconds meet all my needs. Nothing against derailleurs unless you have to dismember the bike.

The range issue could probably be solved by adding a Speeddrive. But this combo might end up costing (almost?) as much as the Rohloff. Personally for me the relative obscurity (unproven, what about replacement parts in the future, will the company be around, maintenance) of it makes it a no go at present. If i were going for a cheaper sortoff alternative to the Rohloff i'd go for a 7 speeds hub plus Speeddrive or possibly a Dual Drive.

What I spec'd on my new Swift was the 8spd Nexus on the rear and then a dual chain ring up front. I'll still have good ground clearance at the rear and a wide range of gears that I can manually select the front range. My intent isn't so much to switch on the fly but have a hi-low range that I can choose relatively quickly if needed without the expense of a Schlumpf setup and not a lot of extra weight.

Cool! That sounds exactly like something was thinking about. But a few things i don't understand:

what about your chainline, with the short chainstays of a folder doesn't it get pretty messed up with one or both of the chainrings?

The second chainring, is that a really small one so that you can achieve climbing granny gears?

Doesn't this setup mean you must use a skinny der. type chain?

I would love some pictures and close ups please!

Ay ideas on what chain, cranks and chainrings to complement my 7 Speed Sram hub?

Thanks for this info!

The chainline is actually better than using a derailleur on the back. The smaller one is as you surmised; just a granny gear range. I went with a Wipperman stainless chain and a small chain tensioner. I went with Deore parallel push brakes too. I hope to have pics in about a week as the bike isn't totally complete yet. I can't wait to get some time on it. It should be a very unique bike with a sort of retro/old school feel combined with very modern aspects biased toward performance.

I am still debating on a few things. I may go with a Brooks saddle combined with a Thudbuster if it doesn't spoil the lines of the Swift. I have spent a lot of time agonizing over the details and deciding just how I want to go with it. It was an evolving concept that I was able to piece together with the help of Peter (desinger of the Swift (aka Xootr). I have tried not to get bogged down in minutia but I am sweating every detail as I took a gamble on going with a green powder coating instead of the more usual black. I wanted the durability of the powder coating. I then with black old school style fenders for a little contrast. I asked Peter to make me some yellow decals to go with the green instead of the white ones but I'll have both to try. I am either going to have something very unique and sublimely beautiful or Frankenbike! I'll be sure to post pics when it is all sorted out.

Sounds like a unique and very interesting bike. Look forward to the pics! Thx for info.

SNIP
I must say that I totally agree with the effciency difference between a derailleur/cassette drive and an internal gear hub. After 3 months of commuting with the SA-5, here are my impressions:

"Mushy"..."muddy"...I like to describe it as pedaling with rubber cranks. Feedback through the pedals is anything but direct...like pedaling on mashmallows. It's a very weird feeling that I just could not get used to even after 3 months of use. Let me take you through the 5 gears:

1 - feels like I got rubber cranks...in the steep hills while in first gear, I fail to feel the bike surge forward with every downstroke...where is all my pedal power going to?
2 - this is the direct-drive of the 5 gears...feels solid, but not very useable except for slow, seated climbs...I prefer climbing steep hills in 2nd than 1st, as at least I feel as if most of my power is moving the bike forward.
3 - not as solid as 2nd, but is definitely the most useable of the 5...good for cruising ~15mph.
4 - here's where the "rubber cranks" feeling starts to kick-in again...you really start to feel your input being sucked-away by the gear hub mechanism, and you really have to work harder in this gear to pick-up the pace from 3rd.
5 - now this is the most interesting place...the rear hub now sounds and feels like my chain is connected to a coffee grinder, and all my power is being replaced by noise and friction...I'm not picking-up any speed at all from 4th, and there is almost no feedback from pedal, to cog, to rubber, to pavement, and hence my immediate reaction is always to down-shift back to 4th to get some feel back into the pedal stroke. This gear is best reserved for downhills in tailwinds. By this time, my hub is making so much noise, other riders are taking notice.

SNIP

james_swift, the SA 5 speed has direct drive in 3rd gear, 1st and 2nd gear down, 4th and 5th gear up.

It is well known that the wider the spread of an epicyclic gear, the lower the efficiency. In this case, it is heightened by SA saving money by not perfecting the tooth profiles of 1st and 5th gear, unlike 2nd and 4th. Google for a paper by Berto and Kyle comparing the efficiencies of derailleur and various hub gears under a range of input power (hub gears get noticeably more efficient at higher power).

By the way, until the 50s and 60s, hub gears were often used by racers (particularly in England) in preference to derailleurs. The Tour de France has been won on hub gears...

Google for a paper by Berto and Kyle comparing the efficiencies of derailleur and various hub gears under a range of input power (hub gears get noticeably more efficient at higher power).

By the way, until the 50s and 60s, hub gears were often used by racers (particularly in England) in preference to derailleurs. The Tour de France has been won on hub gears...

LWaB!! thanks for the pointer to Berto and Kyle. I've wanted to see some independent research with graphs for some time.. Nice article, even considering it being done over 5 years ago. At some point, I wouldn't mind seeing testing results from the newest hub gear systems as well.

Bruce