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  1. #1
    Cool Guy Training.Wheels's Avatar
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    Need some advice with SRAM A2 w/coaster brake on a Tern Link Uno

    Not very technically savvy I am, so bear with me please. So what do I need to know before purchasing an A2? Is it one product that can be installed and modified onto any bike or do I need a specific type for 20' wheels? Also, how should I go about installing so that it is customized optimally for me? Will it be easy? Thanks in advance!

  2. #2
    mermaids are nocturnal Nightdiver's Avatar
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    SRAM makes two versions, one for smaller wheels (optimized for 20" I think), and one for full size (559, 622) wheels. As for customizing it, I really don't think you want to go to that sort of trouble without putting in some decent miles first to make sure. Why not just get the Tern Verge Duo? Problem solved...

  3. #3
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    Quote Originally Posted by Training.Wheels View Post
    Not very technically savvy I am, so bear with me please. So what do I need to know before purchasing an A2? Is it one product that can be installed and modified onto any bike or do I need a specific type for 20' wheels? Also, how should I go about installing so that it is customized optimally for me? Will it be easy? Thanks in advance!
    The easiest way to go about this is just to buy a ready to go SRAM A2 Automatix wheelset that's -pre-built and pre-modified to reflect a higher shift point -- stock will be about 7-8mph, whereas I prefer something like 13 to 14mph and Bruce Metras is the guy who had done this very well. I personally have the Sturmey Archer S2C bought from him and I am really digging it with my now Speed Duo and am impressed with the way he took care of it before selling it to me!
    Trek 5000 carbon road bike
    Masi Speciale CX touring bike
    Dahon Mu SL (performance hybrid road bike)
    Dahon Speed Duo (slow poker shopper or coffee getter bike)

  4. #4
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    Yep I have two A2s one with and one without a coaster brake. I love the A2 and much prefer it over the S2C.

    The one for smaller wheels has its change point set at the factory to ensure the same change point as the one for larger wheels. This seems stock at around 7-8mph as stated. The one for smaller wheels seems to comes in 28h version though and the other in 36h. My two are fitted on a Brompton (16" wheel) having the 28H version and another 36h version with coaster brake on my Moutlon.

    The 28H one on the Brompton changes around 8mph and the one on the Moulton at around the same point. I had to modify The Brompton one to fit in the smaller dropout width of 112mm of the Brompton. Took off one of the lock nuts and had the other one cut down about a mm. Had it about a week now commuting and so far and all good. As standard they come in 120mm OLD with spacers to increase that to 130mm.





    Fitted to my belt drive Moulton TSR2, 120mm OLD so just dropped straight in to replace the Sturmey Archer S2C.






    I would like to open them both up and maybe increase the change point to 10mph but need to investigate further about how to change/make a new spring to do that. On both wheel builds, I used washers to take account of the thinner steel flanges. Not sure if it is necessary but the spoke bends and heads seemed to sit better with them fitted.

    Ps this is a nice little write up (tanslated) I found with some pics.

    http://translate.google.com/translate?u=http%3A%2F%2Fwww.scheunenfun.de%2Fsram-automatix.htm&hl=en&langpair=auto|en&tbb=1&ie=UTF-8

    From that page

    The switching points of a SRAM automatic hub 28 spoke hole:
    20 inch wheels for = 15 km / h
    = 24 inches to 18 km / h
    26 inch = about 19.5 km / h
    = 28 inches to 21 km / h

    The switching points of a SRAM automatic hub 36 spoke hole:
    20 inch wheels for = 12 km / h
    24 inch = about 14.5 km / h
    = 26 inches to 16 km / h
    28 inch = about 17.5 km / h

    This tallies with my 36h one changing at 7.5-8mph on my 20inch wheel. If I had fitted the 28h one to this it would change at nearer 10mph.

    Oh and I purchased my last one from these guys though they say the 28h version with coaster brake will not be avaliable until late August.

    http://www.bike-mailorder.de/shop/ad...omatix&x=0&y=0

    Finally the weight quoted 980g is optimistic. I weighed mine as closer to 1.1kgs.


    Regards

    Jerry
    Last edited by jerrysimon; 07-25-12 at 12:55 AM.

  5. #5
    New usename ThorUSA brakemeister's Avatar
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    spoke washers nice touch

    thor

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    Thanks Thor. As you can see the second build (top pic) I found out about seating the heads properly into the washers, the lower pic showing my first build with this hub you can see I did not do that properly on. I have since gone back and redone it. These last few years learning how to build wheels has been a blast. There is so much to learn and I can see why some say even after a life time of doing it, there is always something new.

    There is nothing like the buzz you get from buying parts, building a good wheel and taking it out for the first ride

    Regards

    Jerry

  7. #7
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    training wheels you might need to check the number of holes that sram has because the one on the verge is 20h which you cannot buy anywhere but the regular one from amazon is 36h only i think which you'll need a rim for that. I was also thinking of the same thing in the future for my uno but I wasn't too interested in the automatix because I like to spin up the hills alot and be in control of the gear i'm in, last thing I want then doing that is my bike kicking into high gear in the middle of the hill. I intend to choose the sturmey archer s2c instead when the time comes.

    That was the number one reason I chose the link uno over the verge cause I like to customize and upgrade, so why pay extra for stuff you didn't want. I changed out the seat (brooks), pedals (mks quick release), grips (ergons!) and I like the option with the trolley rack if you do multi mode commute alot. Next will be my rear wheel! I like how the parts are alot more standard than my strida which I can change on a whim.

  8. #8
    Cool Guy Training.Wheels's Avatar
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    Quote Originally Posted by Azreal911 View Post
    training wheels you might need to check the number of holes that sram has because the one on the verge is 20h which you cannot buy anywhere but the regular one from amazon is 36h only i think which you'll need a rim for that. I was also thinking of the same thing in the future for my uno but I wasn't too interested in the automatix because I like to spin up the hills alot and be in control of the gear i'm in, last thing I want then doing that is my bike kicking into high gear in the middle of the hill. I intend to choose the sturmey archer s2c instead when the time comes.

    That was the number one reason I chose the link uno over the verge cause I like to customize and upgrade, so why pay extra for stuff you didn't want. I changed out the seat (brooks), pedals (mks quick release), grips (ergons!) and I like the option with the trolley rack if you do multi mode commute alot. Next will be my rear wheel! I like how the parts are alot more standard than my strida which I can change on a whim.
    So do you think I'll need a new rim and spokes as well? Will I also be able to convert my Tern into a belt drive? I might as well get everything out of the way. How much would you estimate this all costs for parts and labor considering that I already bought my SRAM? (i.e. spokes, rim, belt drive, +labor)

  9. #9
    Cool Guy Training.Wheels's Avatar
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    @jerrysimon, so are you saying your Moulton has 20 inch wheels and you didn't modify your 36h hub to shift at higher speeds? If so, how does shifting at around 7-8 mph feel? Is it acceptable? I'm thinking about listening to Nightdiver and seeing if I like it un-customized first. Also, what is "OLD" and how come yours is 120mm whereas the one I ordered is 130mm? Thanks in advance.

  10. #10
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    Quote Originally Posted by Training.Wheels View Post
    So do you think I'll need a new rim and spokes as well? Will I also be able to convert my Tern into a belt drive? I might as well get everything out of the way. How much would you estimate this all costs for parts and labor considering that I already bought my SRAM? (i.e. spokes, rim, belt drive, +labor)
    Sorry I couldn't answer these questions fully for you yet but you can also lace a 36h hub to a 20h rim easily but you might have to do it yourself because stores don't want the liability issues I think sheldon brown has info on this. My friend tried asking and none of them will do it and he has a 20h rim. in the end he got ahold of a old duomatic from some old bike on craigslist and will do a hub swap with his mu uno. In the end I think it ran him $150 or so. and for the belt drive I don't think you can do it on the link uno because of the way the chain goes through the frame. You aren't going to gain much going from chain to belt since your uno also comes with a chain cover. Keep that and the chain clean and it works just as well without the bother of belt skipping which I get when I put too much torque on the pedals (I'm a strida owner too).

  11. #11
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    The 36h one changes stock at 7-8mph on a 20 inch rim yes. The 28h ones are configured for smaller rims and change at a higher point hence on the 16" Brompton rim they also change at 7-8mph. This same 28h version would therefore probably change at nearer 10mph on a 20" rim. In terms of the change point, I commute on a very flat terrain so it is fine. I think if I was commuting on more uneven terrain I would want changing at around 10-11mph. This is quite subjective and depends on your terrain, riding style etc.

    They come with an OLN of 130mm but this includes two removable spacers which then take it down to 120mm if you then remove them.

    Belt wise, as stated you need a frame with a split in it to be able to get one on. Belts are not splitable

    Regards

    Jerry
    Last edited by jerrysimon; 07-26-12 at 07:58 AM.

  12. #12
    Senior Member kbabin's Avatar
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    What is the chainline for this hub... I can't find that info on SRAM or anyother site.

    Thanks
    Kevin

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