New article about the SRAM Automatix two-speed hub. We have information on maintenance, choice among variant models, and how to adjust the speed at which it shifts automatically.
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SRAM Automatix 2-speed hub
6 thoughts on “SRAM Automatix 2-speed hub”
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Dear John,
I’m thinking about purchasing this hub. But i want to use it on my single speed bike. It’s a retro Raleigh racebike. My current sprockets are 46/18 and that’s fine for normal riding but i live in Holland so the hills are most difficult.
How can i calculate witch ratio i need tot have lighter with the hub and when it changes gear it will be something like 46/18.
I have an SRAM automatix hub with a 19 and a 24 sprocket. So now i want to calculate which sprocket i need on the crank.
Hopefully you can help me:)
Hills are difficult in Holland? Well, not much though I do understand that there are hills in the southeast of the country. Even without hills though, having a lower gear for acceleration is helpful.
You say 46/18 but do you mean in the high gear or the low gear? And what is the wheel size?
Once you assemble this information, you can answer the question using http://sheldonbrown.com/gear-calc.html. If the 1:1 gear is not the one you want to be like a 46/18, then adjust the size of the chainwheel until the other gear, with the sprocket you will use, gives you the development you get with 1:1 gear and 46/18. The chainwheel is going to be larger in proportion to the size of the sprocket, but also will be in inverse proportion to the hub ratio.
(new chainwheel size) = 46 * (your sprocket) / (hub ratio * 18)
Do you have a diag for the version with no brake? Looks like there is nothing to stop the L/H bearing cap rotating!
There’s a diagram on page 10 here now also on our page, and the user manual linked on our page shows a locknut. Sorry about the late response.
Do you know where I can buy the SRAM Automatix 2 speed
I see a couple for Sale on eBay.