Some advice on dual drive hubs

[jaffaman]

Hi, I have a Giatex "folder" (two actually - one for the wife) which I love and want to upgrade. I chose this as a folder as it is rated to carry my 120kg frame which most other folders don't.

I know this is recumbent land, but I know that you will know about small wheels and dual drive hubs, and a few of you are closet folders anyway so I'm hoping you'll forgive the intrusion . Bike has 406 wheels front and back. Current setup on the main bike is 7 speed freewheel with 14-34, and I have a 48/38 on the crank (22-67 gear inches). My second bike has the original 14/28 6 speed freewheel and single 52 on the crank (36-72 gear inches). Problem is I am now fit enough that 48/14 is no where near fast enough, though I like the 38/34 for hills still - I originally upgraded for hills (live in the "Hills District" of Brisbane - aptly named).

So, upgrades are being considered. Greenspeed will build me a Velocity Aeroheat with a SRAM Dual Drive II in it (not cheaply, but not too bad either, and anything I do is going to cost and this will be a lot less than buying a new folder with a dual drive built in). I would fit the new wheel to the second bike to give a 52 at the front, and run a 9 speed 11/34 at the rear. (22 - 125 gear inches). The original bike is 126mm OLD, but it is a basic steel frame and I took it out to 135mm fine when I fitted the 7 speed (though I only needed 130), so I'm not expecting problems there.

Questions - are there any issues with the Dual Drive?
1. I read that some hubs don't like being on their side (leak) but being a folder that is a usual condition for me. Are there any problems with this with the Dual Drive - I haven't heard it mentioned, but wanted to check?
2. Do I need to use the SRAM derailleur if I use an SRAM shifter, or should I just get a shifter for the click box and use standard derailleur/shifters?
3. I know I could go Capreo with 34/50 on the front (25-108 gear inches) but the front doesn't really have a place for a derailleur. While I have one working, it is a triple that just manages working as a double because the angles on the seatpost are all wrong, and I do get some cross chaining issues with it, and I fear it will be hard to get a compact front chainring system shifting properly, or at least properly across the gear range. The dual drive sounds cleaner and simpler to me - Does that sound right or should I reconsider the Capreo?
4. I'm assuming that the aeroheat will support my 120 kgs OK (my standard wheels have been fine - an advantage of small size) or is it worth getting them to build with a DeepV or something else just to be sure?

Any other thoughts? I would appreciate any opinions anyone has, especially if you have experience with the Dual Drive. Cheers.

[Low Racer]

Hi Jaffaman,
I am a fan of Sram DD. Infact I have a trike, a folder and a tandem with Sram DD. I just love the functionality and simplicity of gearing it give you without the complexity of triple chain rings. I will try to answer your questions to my best ability as a Sram DD user.

Questions - are there any issues with the Dual Drive?
1. I read that some hubs don't like being on their side (leak) but being a folder that is a usual condition for me. Are there any problems with this with the Dual Drive - I haven't heard it mentioned, but wanted to check?

= Sram DD is not bath in oil. Had laid my bike on its side without problem. The shifting rod does need periodic light lubrication. Of the three bikes, the folder has the 1st generation of Sram DD (about 9 yrs old). I noticed significant improvement when I put a few drops of Triflow into the hub via the rod insert.

2. Do I need to use the SRAM derailleur if I use an SRAM shifter, or should I just get a shifter for the click box and use standard derailleur/shifters?

= I have tried this with a Shimano rear derailleur and it didn't work as well. I missed some gears no matter what I tried. I believed you do need to use the shifter that come with Sram DD for it to function properly. As for the rear derailleur, you can go with anything really.

3. I know I could go Capreo with 34/50 on the front (25-108 gear inches) but the front doesn't really have a place for a derailleur. While I have one working, it is a triple that just manages working as a double because the angles on the seatpost are all wrong, and I do get some cross chaining issues with it, and I fear it will be hard to get a compact front chainring system shifting properly, or at least properly across the gear range. The dual drive sounds cleaner and simpler to me - Does that sound right or should I reconsider the Capreo?

= Don't know about capreo

4. I'm assuming that the aeroheat will support my 120 kgs OK (my standard wheels have been fine - an advantage of small size) or is it worth getting them to build with a DeepV or something else just to be sure?

= If not mistaken, the minimum spokes count that comes with Sram DD is 32 and goes up to 36. If you are concerned that 32 might not support you weight, go with 36 and that's plenty enough to make a strong wheel.

Any other thoughts? I would appreciate any opinions anyone has, especially if you have experience with the Dual Drive. Cheers.

[jaffaman]

Thanks for that. I was pretty sure the oil thing wasn't a problem, but I wanted to be really sure. Not much point in a folding bike if I can't lay it on its side. It's nice to hear from someone who likes the system enough to have three bikes with it - that's a good sign.