SRAM Dual-Drive, what are the con(s)?
01-07-06, 06:59 PM
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SRAM Dual-Drive, what are the con(s)?
After a crap day of bicycling, somethings got to change!
My chain came off 3-4 times today during my ride. Everything is perfect and up to spec and I heard this may be called "chain slap". It's a pain in the ass is what it is!
When I got home for whatever reason my web searching led me to a bike with an SRAM Dual-Drive. Basically this bike has 21 gears and from what I understand, none of the problems I was having because everything was contained in the rear derailer. My question is - is this too good to be true? The big advantages I see over a traditional derailer system is:
+ Everything is in the rear derailer, no chain slap, more reliable
+ You can shift when you are stopped
+ Everything is controlled from one shifter on the bike - not two
+ I can send money SRAM's way instead of Shimanos
My other option is to go with 9 speed but run a single ring up front.
Is the Dual-Drive too good to be true?
My chain came off 3-4 times today during my ride. Everything is perfect and up to spec and I heard this may be called "chain slap". It's a pain in the ass is what it is!
When I got home for whatever reason my web searching led me to a bike with an SRAM Dual-Drive. Basically this bike has 21 gears and from what I understand, none of the problems I was having because everything was contained in the rear derailer. My question is - is this too good to be true? The big advantages I see over a traditional derailer system is:
+ Everything is in the rear derailer, no chain slap, more reliable
+ You can shift when you are stopped
+ Everything is controlled from one shifter on the bike - not two
+ I can send money SRAM's way instead of Shimanos
My other option is to go with 9 speed but run a single ring up front.
Is the Dual-Drive too good to be true?
01-07-06, 08:13 PM
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I've had luck with the 3rd eye chain watcher (prevents chain drop to the inside of the small front chainring). Looking at the MTB review site, though, most found it too fragile.
Doesn't answer your question, but may be an alternative to your problem
https://www.sheldonbrown.com/harris/chains.html
Doesn't answer your question, but may be an alternative to your problem
https://www.sheldonbrown.com/harris/chains.html
01-07-06, 08:25 PM
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Everything is not up to spec or you are shifting wrong. What you are experiencing is not normal. You just need to fix your bike.
01-07-06, 08:52 PM
#4
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As much as I think it's a great product, I'm not sure it'll solve your problem. If you are shifting off the inside chainring, it'd be better to get a Third Eye Chain Watcher. If it's simple chain slap, then you need to check the length of your chain and/or get a tensioner. But since you ask...
The Dual-drive is the updated 8/9 speed version of the SRAM 3x7, formerly Sachs 3x7. It consists of a 3-speed hub with a cassette body. IIRC, the 3 ranges are 27% underdrive, direct, and 36% overdrive, which you can treat as if they were 3 chainrings WRT gears.
Normally, shifting a 3-speed hub requires no load, i.e. you have to stop pedaling, while the DualDrive improvements supposedly allow shifting under a small load. As far as controls, you still require 2 shift cables - one to the derailleur and one to the hub. Installing it requires adding an additional cable stop on the right chainstay. If you are into mountain biking, the control box sticks out and is vulnerable to damage/breaking, unlike the old 3x7 which used a small chain and was pretty bulletproof. (worst case: the chain was replaceable for $5-10.)
Disadvantages:
$$$ - it will require a new wheel built, and the hub isn't cheap.
Slight efficiency loss in underdrive and overdrive
vulnerable clickbox (DualDrive only)
weight
bolt-on only, not quick release.
I ran a 3x7 hub for many years, as part of a 63-speed drivetrain. The gear range for my 3x3x7 setup was enormous: 17 to 144 inches. The hub was very reliable and for the most part I didn't notice the efficiency loss. The hub bearings were astonishingly smooth - the wheel would spin forever with just a little push. Maintenance consisted of a couple drops of oil each spring and maybe a couple more mid-summer. The only other thing I can think to add is that the unit sounds like you've got a playing card stuck in your spokes - the unique double-click always sounded cool to me, but it's something you have to get used to.
The Dual-drive is the updated 8/9 speed version of the SRAM 3x7, formerly Sachs 3x7. It consists of a 3-speed hub with a cassette body. IIRC, the 3 ranges are 27% underdrive, direct, and 36% overdrive, which you can treat as if they were 3 chainrings WRT gears.
Normally, shifting a 3-speed hub requires no load, i.e. you have to stop pedaling, while the DualDrive improvements supposedly allow shifting under a small load. As far as controls, you still require 2 shift cables - one to the derailleur and one to the hub. Installing it requires adding an additional cable stop on the right chainstay. If you are into mountain biking, the control box sticks out and is vulnerable to damage/breaking, unlike the old 3x7 which used a small chain and was pretty bulletproof. (worst case: the chain was replaceable for $5-10.)
Disadvantages:
$$$ - it will require a new wheel built, and the hub isn't cheap.
Slight efficiency loss in underdrive and overdrive
vulnerable clickbox (DualDrive only)
weight
bolt-on only, not quick release.
I ran a 3x7 hub for many years, as part of a 63-speed drivetrain. The gear range for my 3x3x7 setup was enormous: 17 to 144 inches. The hub was very reliable and for the most part I didn't notice the efficiency loss. The hub bearings were astonishingly smooth - the wheel would spin forever with just a little push. Maintenance consisted of a couple drops of oil each spring and maybe a couple more mid-summer. The only other thing I can think to add is that the unit sounds like you've got a playing card stuck in your spokes - the unique double-click always sounded cool to me, but it's something you have to get used to.
01-08-06, 08:37 AM
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Thanks for the responses!
I ride primarily on the street right now so I'm not worried about beating up the box.
I know it sounds crazy, but as soon as my current tires expire I am going to have a set of 650B wheels built up with the S-RAM drivetrain. My current Kona Hoss-D is a mountain bike made for clydesdales but what a frankenstein it's turning into!
I ride primarily on the street right now so I'm not worried about beating up the box.
I know it sounds crazy, but as soon as my current tires expire I am going to have a set of 650B wheels built up with the S-RAM drivetrain. My current Kona Hoss-D is a mountain bike made for clydesdales but what a frankenstein it's turning into!
