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-   -   Downtube nova with sram automatix (http://www.bikeforums.net/folding-bikes/936895-downtube-nova-sram-automatix.html)

don68 03-05-14 05:39 PM

Downtube nova with sram automatix
 
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Hello everyone, new to this forum and would like to share my nova with a new to me sram automatix. Did a little ride this morning by the San Diego Bay, the weather was perfect. The 2speed worked like a charm but was a pita to convert. Happy riding!!!

P7HVN 03-05-14 08:14 PM

What was the main problem converting it? I had thought about picking up one of the SRAM pre-built wheels from Respect Cycles to put on my Downtube VIII, to clean it up a bit...

downtube 03-06-14 12:08 PM

Looks nice!

Yan

BassNotBass 03-06-14 12:13 PM

Can you change the weights in the centrifugal clutch to change the speed at which it shifts?

BruceMetras 03-06-14 12:50 PM

Quote:

Originally Posted by BassNotBass (Post 16554319)
Can you change the weights in the centrifugal clutch to change the speed at which it shifts?

You could, but it's way easier to change the spring tension that keep the flyweights from engaging (or wind new springs - what I did) .. I toyed with the idea of drilling the weights and refilling with solder if I went to far, but that would be fairly time consuming .. if you had a source for a supply of weights, might be fun, but changing spring tension is all that is needed .. all of my Automatic hubs shift at around 13.5/14mph in wheels from 406 to 700c ..

don68 03-06-14 01:32 PM

Quote:

Originally Posted by P7HVN (Post 16552396)
What was the main problem converting it? I had thought about picking up one of the SRAM pre-built wheels from Respect Cycles to put on my Downtube VIII, to clean it up a bit...

Well the nova has vertical dropout, so i needed a way to tension the chain. Also gonna need to change the BB to get correct alignment (its on the way). What I should've said was it's not plug and play...
I bent the spring on mine to make it shift at a faster rpm. Stock was at 8mph and after the mod it's at 10.5mph, which is perfect for me.

Also Yan, I ordered a white Nova for my Girlfriend 2 days ago, any news on when it will be shipped? Thanks

don68 03-06-14 01:36 PM

Quote:

Originally Posted by BruceMetras (Post 16554460)
You could, but it's way easier to change the spring tension that keep the flyweights from engaging (or wind new springs - what I did) .. I toyed with the idea of drilling the weights and refilling with solder if I went to far, but that would be fairly time consuming .. if you had a source for a supply of weights, might be fun, but changing spring tension is all that is needed .. all of my Automatic hubs shift at around 13.5/14mph in wheels from 406 to 700c ..

I like your idea about winding new springs, What did you use?

downtube 03-06-14 04:26 PM

Quote:

Originally Posted by don68 (Post 16554591)

Also Yan, I ordered a white Nova for my Girlfriend 2 days ago, any news on when it will be shipped? Thanks

Shipped yesterday....Thanks!

Om,
Yan

BruceMetras 03-06-14 04:48 PM

Quote:

Originally Posted by don68 (Post 16554605)
I like your idea about winding new springs, What did you use?

I was using piano wire .. I'm pretty sure I used #16 ... all this work was done years back.. you vary the number of winds to get in the ball park .. once I wound a few springs, I could plug and play .. you could also use a second 'stock' spring (if you could source it) to modify shift point .. there was someone on here that used a spring from a Bic pen that worked for him at the time, but pen springs are compression springs and not torsion springs as used in the Automatix.. so not sure how his long term results went... on mine, I haven't had to make any further adjustments through the years .

don68 03-06-14 05:59 PM

When I bent the spring, I wasn't sure if I damaged it since it's so small and thin. I'm gonna use your idea and make a few springs for spares. Thanks Bruce


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