As soon as the parts arrive, I will be doing the same thing, SDD and Schmidt SON, on Velocity Cliffhangers with 36 spokes front and rear.

I've got the Sachs Dual Drive on my BF.

It seems to work ok. It is configured with the Shimano 9s brifters, but they just seem a bit funky.

I think the Sturmey Archer S3X bar end shifter should shift it, so I'll probably try that sometime.

It seems to me that the overdrive has significantly higher resistance than the direct drive, so I'd prefer using a large chainring to the Dual Drive + Overdrive.

That's great.
.

I was skeptical but now I'm interested. You get the 1x benefits of not worrying about chain crossing and the range of a triple FD, you just have to pay a weight penalty.


I have a 130bcd Rival crank that I love but the lowest front chainring you can fit is 39t, so I keep moving it to different bikes and getting annoyed with it. So SSD gives you a weird option for converting some 130bcd crank road bikes to a wider gear range without replacing the crankset or RD or cassette even.

What happens when an SDD fails?

No one knows. I have yet to come across reports of failure or breakdown.

I haven't had a SDD fail per se. We have replaced the SDD on at least 2 pedicabs when they were worn out. Again, these hubs were on pedicabs that are used as service vehicles, working cabs. Heavy use day and night after day and night. With crazy loads by bicycle standards. Lots of weight, torque, forces, hills, etc. Eventually as the SDD wears it gets lots of resistance in the hub. I particularly noticed the drag when in the lowest gear on the IGH. Hub felt 'gritty' as well, for lack of a better term. I am assuming the planetary gears inside the IGH were just worn out. Possibly could have been rebuilt but cheaper and easier just to replace the whole hub as we did not have sufficient experience w/ the internals on the SDD IGH and it was difficult to find a way to service them through SRAM or an LBS. Pedicabs wear out their parts. Just happens. Chains and cassettes are easy to replace and wear out long before the internals of the SDD IGH. Rear axle bearings have also been replaced on these cabs. Both after thousands of miles and thousands of hours of use under heavy load over a 8-10 year span. A bicycle, even heavily loaded for touring, wouldn't be subject to the same level of wear. I wouldn't consider the SDD to have failed, just end of life.
That being said, the SDD on my Bike Friday triple is good to go. This bike gets loaded down with three riders and panniers and sees a lot of use. It serves as my school bus to get my youngest 2 kids to elementary school and for longer trips and errands through town. It is ridden nearly every day. Never had any problem whatsoever with the hub on the triple nor does it show any noticeable signs of wear on the IGH. Our triple is about 9 years old and has seen multiple tours and near daily use. Probably more demand on this particular setup than the largest majority of SDD hubs sold. Again, no problems.
A few photos of Cycles Maximus pedicabs for point of reference. Not me in the photo, BTW.
http://bikeforums.net/attachment.php...hmentid=520348http://bikeforums.net/attachment.php...hmentid=520349http://bikeforums.net/attachment.php...hmentid=520350
A few more of Austin pedicabs in use, the cab with ART and Herb Bar is one of the cabs that we replaced the SDD after wearing it out. I have spun so very many circles on that trike.
http://bikeforums.net/attachment.php...hmentid=520351http://bikeforums.net/attachment.php...hmentid=520352http://bikeforums.net/attachment.php...hmentid=520353http://bikeforums.net/attachment.php...hmentid=520354

That's great info, thanks. It's good to know it doesn't just break down and leave you with a dead hub somewhere in the middle of nowhere. I heard traditional IGH hubs start skipping or die so that only one gear can be used. A little resistance is something you could endure for a while if you are on tour somewhere far out

Of course, the SDD is not rated, designed or warrantied for commercial, or work vehicles.

In post number 10 above, I mention that the Sturmey Archer bar end shifter works fine with the Dual Drive for my first few miles with that combination, I gave a link in that post to another bikeforums thread where several others say they have been using that combination for years. I used the SL-S30 bar end shifter according to my photo.

I find no extra resistance in the overdrive. Perhaps yours needs some renewal of the lubrication if you are using an old Sachs, that has to be quite old. I would not know how to lubricate it, but that would be my first plan of attack. Maybe the Bike Friday folks could advise you on that?

Looks like you are using the Dual Drive as a transmission for gearing, but you are not putting the weight of the cab onto the axle with this configuration. My concern for loaded touring was the strength of the axle under a heavy load.

Yes. Transmission w/ separate axle with open differential on pedicab. Lots of load on the drivetrain, though. Also, Cycles Maximus is now offering the NuVinci hub as option on their pedicabs. Not as broad a range as the SDD. SDD is still recommended OE in hilly terrain. NuVinci hub is fine for New York or London but not enough range for the hills of Austin.
Pass through axle on my Bike Friday. Seems VERY sturdy. Has a steel axle with 15mm nuts. My best guess offhand is 9mm axle as it seems more heavy duty than normal bolt on axle. No quick releases on my Bike Friday.

After this conversation about the Dual Drive, I decided to ride my fold up bike instead of my rando bike today for my 20 mile exercise ride. A few hills in the first few miles, then mostly flat, the last five miles is very hilly. Thus, got a chance to give the Sturmey Archer bar end shifter on the Dual Drive a good test on the hilly section at the end. It passed the test with flying colors, very happy with the shifter.

http://bikeforums.net/attachment.php...hmentid=520456

As noted above, am running an eight speed Sram 11/32 cassette. It is a cheap Shimano derailleur, shifts a little slow but I blame that on the long full length outer housing, it is long enough that I need a tandem length cable.

http://bikeforums.net/attachment.php...hmentid=520458

My rando bike also has the same cassette, a triple crank and friction downtube shifter. I found the Sturmey Archer indexed shifter to be much preferable to the downtube friction shifter on the other bike. My derailleur touring bike also uses that same eight speed 11/32 cassette and a triple up front, that shifts with a friction bar end shifter, which I am so used to that I can almost shift it as well as an indexed shifter.

I was thinking about your comment during my ride today.

Regarding cross chaining, it all depends on how you define cross chaining. If you define cross chaining on a triple to mean that you can use all sprockets on the back when on the middle chainring, then you are right when you say "You get the 1X benefits of..."

I however define cross chaining as the two most out of alignment gears for each chainring. Thus, when I am on the big chainring on my triple, I do not use the two biggest sprockets, when on the middle chainring I do not use the innermost and outermost sprockets, etc. This has not cost me a lot of gears, with my eight speed cassette, I only use six gears for each chainring. Thus, my 24 speeds is really only 18. But, there are no redundant gears in that 18. Several of the cross chained gears that I do not use are exactly the same as ones that I have and use. This means that with the Dual Drive setup, I try to avoid using the innermost and outermost sprockets on the cassette, but they do get used on steep hills for both up and down. So, the way I define cross chaining, I cross chain a bit more often then I do with a triple.

Another consideration is that you can shift the Dual Drive when stopped. This occurs especially when you are pedaling hard to try to get through a green light before it turns red, but you are a bit to late and have to brake hard for the red light. In this case, you end up having to start out in a higher gear - unless you have an IGH (like the Dual Drive) where you can downshift while stopped.

The last point I would make in comparing the Dual Drive with a triple is that with a triple you can change chainrings to different sizes. That is getting harder to accomplish with front derailleurs that have cages shaped to specific chainring sizes, etc. But over a decade ago, it was common to change chainrings to meet your needs. Thus for my derailleur touring bike with a 52/42/30 triple, when I went on a tour and wanted lower gearing, no problem, put on a 24 instead of the 30 to get lower climbing gears. I also on one tour changed out the 52 to a 46 for half step gearing. But, the dual drive has fixed ratios, when you go into overdrive from the middle (direct drive) gear, you upshift by 36.2 percent. Or if you are in the middle (direct drive) gear on the Dual Drive and down shift, you reduced your gear to 73.4 percent of where you were before you shifted. These ratios can't be changed like you can change the chainrings on a triple. So, a triple offers a bit more flexibility in gear choices.

So, the Dual Drive has some advantages but some disadvantages. And in my case as I noted above I used a Dual Drive for one simple reason, I can't fit a front derailleur on that bike.

One more issue to contemplate. I went on a guided tour several years ago, the guide had a Bike Friday with a Sachs predecessor to the Dual Drive. His wife had a derailleur triple. He said he wished that they still made that hub because his wife spins out due to lack of high gears (with the 20 inch wheel) where he has an overdrive with his Sachs hub. He was unaware that the Sram Dual Drive existed, which I informed him of. I suspect by now she has the Dual Drive on her Bike Friday to get the overdrive gears that she needed to quit spinning out.

Another neat thing about the SRDD is that the shifts are crisp and nearly instantanous, akin to cogset shifts with an RD. None of the lull of FD shifting with chainrings. Click, and boom, you're on the lower SDRR gear. Click, and boom, you're back up.

This is my SDD-equipped light tourer with 20-119 gear inches on tap...
https://dl.dropbox.com/s/vzyngld7ubp..._HDR.jpg?raw=1

Had to dig up this post again since I didn't want to start a new one.
Does anyone know how the latest SRAM DD compare to the original Sachs versions? I am asking because I did some reading and it was pointed out that there has been 4 or 5 generations of 3x7 and some of the older Sachs versions were better and some were worse. There is an older but good German article about it:
3x7 Kombi - KARSTILO.net

But I have not found any comparison against the latest SRAM branded 3x7 to 3x9. I have a 1994 touring bike which came with the original Sachs 3x7.
3x7
It was working great until about two months ago. First part of the clutch assembly broke and then the sliding key. But this after 23 years!!! of use with basically no maintenance. And I was able to get the parts in Germany.
However after I fixed all the interior parts, the hub flange broke. This was a bummer. I assume this happened because I had a spoke replaced some time before and there was uneven tension on the hub.
Long story short I found a replacement hub on ebay. It is the newer model, the last Sachs 3x7 which was also rebranded as SRAM Spectro 3x7.
Sachs 3x7 hub - HPV-parts.de
www.greenspeed.com.au/pdfs/sachs_3x7.pdf
This is a bit beefier than the original Sachs 3x7. Stronger hub flanges and stronger clutch assembly. It was unused and original packed. With a friend I laced the wheel again using all brand new spokes and I am happy again.
However these older Sachs/SRAM hubs are getting hard to find to stock spare parts and I wonder if I should just switch to a new DualDrive in case something breaks again.
Thanks

Harhir, I can't answer any of your questions. I have seen the Sachs hubs, but never looked at them close.

I read a few months ago somewhere that Sram was going to quit making the Dual Drive hub. I am sure there are still some in the retail pipeline, but they might be much harder to find in a year or two. If I considered buying another foldup bike, I would buy that hub now to make sure I had one.

From the photos of mine (post number 35 above) you can see that the Sram uses a clickbox on the right side of the rear axle. You disconnect that when you pull the wheel off. I have not tried to put a pannier on my foldup bike for a bike tour, but if I did I would have concerns about the pannier and click box not playing well together.

There are a lot more folding bike users that use the Dual Drive, have you asked your questions on that forum?

Sram Took out Sachs in a Leveraged deal, now they've killed off the whole IGH division, after moving it from Germany to Taiwan.


Here is the survivor Sturmey-Archer | CS-RF3 Silver

they make disc Sturmey-Archer | CS-RK3 Silver





:innocent:









.....

I think that there could be no harder test of the Dualdrive than having these on Pedicabs.

I run one along with a 9 speed Der on my Moulton TSR27 and have read elsewhere that given the rather inadequate seals on the DD it's best to use semi-fluid grease rather than a light oil. I'd be grateful for your experience about this given the heavy use given to yours.

Well, I hope the glowing reports here are true, because after literally maybe three miles on my brand new touring folder, the Dual Drive is completely out of whack, leaving me with only the lowest hub gear. The two highest hub gears give me nothing but a truly absurd amount of skipping. It's horrible. Gonna take it back to the dealer I purchased it from and have them try again. I don't know if the chain is too long or it's an adjustment issue with the shifting, but it's really bumming me out. Before purchasing this bike, my main hesitation was the DD system. I'm feeling like I should have listened to my gut instinct on this one.

Edit: Ooooooookay... so I found the problem. The problem is I'm a clumsy idiot. When I took it out of my trunk, I must have twisted the barrel adjuster on the clickbox... several times. It was so far off it's amazing that it had any gears at all. So uhmmmm... move along, nothing to see here....

We have all been there, glad you figured it out.

Sometimes the shifter end of the shift cable does not get seated into the shifter quite right when first installed. I do not mean a Dual Drive issue, I mean all brands and models of shifters. And when it slides into proper place later, a major re-adjustment can be needed.

And sometimes I have trouble getting my clickbox seated exactly right on the axle.

I am quite happy with the Dual Drive on my folder.

Thanks. Good to know. Right now I am trying keep an inventory of spare parts on my older 3x7. Whenever something pops up on ebay, I might buy it...
I just love the concept.

The concept looks to be duplicated in some current Sturmey Archer offerings, but I have no idea of the quality or whether it's otherwise a suitable replacement for the Sram.
Sturmey-Archer | CS-RF3 Silver