SRAM Automatic 2-speed Hub

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Hello brethren,
As part of the 'restoration' of my 1956 JC Higgins,I'm looking to 'upgrade' the drivetrain. The original hubs (front and rear) have seen better days. So, I'm thinking of installing a new sealed bearing front and adding some additional gears to the rear.

I already have several bikes with Shimano IGH rear ends (Nexus 3s and 7s), however I want to avoid cables with the Higgins.
That means (as far as I know), I'm limited to a vintage rebuilt Bendix kickback, a new Sturmey Archer S2C kickback and the SRAM Automatic 2-speed.

Without getting into a 'this hub vs. that hub' debate, I'm leaning towards trying the SRAM unit. I have concerns regarding the long term usage of the Bendix (dwindling supplies coupled with increasing parts costs) and I have read more negative reviews of the SA hub (although I love SA hubs) than positive (heck, there's already a 'rebuild' kit due to faulty production runs). That leads me to the SRAM.

The SRAM unit differs from the other two in that, you don't have to back-pedal to engage the higher gear. Instead, the hub essentially works on centrifugal force and once the force exceeds retaining springs, the second set of gears engage (and then disengage as you slow down). The biggest complaint I've read is that, the hub goes into 2nd gear at too slow a speed. people have overcome this by 'tweaking' the internal spring or changing the gearing ratio. Being that the intended bike will be a 'Sunday rider/slow cruise' ride vs. a commuter, I'm not sure how much of an issue this would REALLY be.

So, has anyone ever used one of these hubs? If so, I'd like to hear from ya! I plan on ordering it (or the SA if I must) in the next week, so this may turn into a review thread.

Cheers,
Dr. T
 
Yeah, I've read that too. It's sort of the opposite effect of it upshifting into the higher gear too quickly. The revolutions have to come down so the springs pull the gearing back down.
I guess it's one of those things where I won't know if it's a pain, until I have it..hahahahaa :mrgreen:
 
Some facts:
-as others mentioned, Sachs made a Duomatic kickback and an Automatic 2speed upon which the current SRAM hub is based
-you can reportedly "force" a downshift on the SRAM hub by kicking back
-the early s2c hubs were shipped with an internal part missing, some sort of spring, I think. The rebuild kit, of course, contains the missing bit. Supposedly, the current ones are shipping complete and fairly reliable. If you order one, though, you might get an old one. After the first batches took a crap on everyone, sales slowed down, so....
-I know a guy with an s2c that has been great (but noisy) for him
-I have a 36h Sachs kickback that I'm trying to convince myself to lace up and run.

Also, be advised that the SRAMs are spaced at 120 and easily respaced to 130mm. The s2c is spaced at 116 or 120mm, and the 120s are easily despaced to 116. The Sachs are spaced at 112mm; i believe the Bendix are about the same. Also, you may have to spread your forks or despace the hub; modern sealed bearing hubs tend to be 100mm and aged US-built forks tend to be 92ish.

hth
-Rob
 
Thanks for all the info dude!
I'll definitely measure the frame and fork before ordering anything.

This old Murray is pretty wide front and rear, so hopefully I'll be OK.

Thanks again!

Cheers,
Dr. T

Sent from my SCH-R720 using Tapatalk 2
 
Quickly measured the frame/fork last night.

The rear dropouts are 4 5/8" apart, or 117.5 mm. I'm pretty sure spreading them slightly to get the 120 mm spacing should be pretty easy to do.

On the fork, the legs are 3 5/8" apart, or 92 mm. The hub I'm look at is 100 mm, so....might have some work to do there. Fortunately, I have one in my stash that I drilled out for 11 ga spokes, so I can test fit it.

Stay tuned.

Cheers,
Dr. T
 

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