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  • SRAM gx t type transmission
  • sam1988
    Free Member

    Thinking about a new drivetrain. The above states it’s designed around a 55mm chain line, how important is that? My hb130 had a udh so will fit but had a 52mm chain line according to hope. I’ve emailed SRAM but not heard anything back.

    v7fmp
    Full Member

    can your bike definitely take T-Type? Only reason i ask, is my friends Atherton has a UDH, but due to the dropout shape/design of the chanistay, he cant actually run Transmission. Its a misconception that if a bike has a UDH it can 100% use the Sram system.

    Otherwise, i cant help with the chain line question, sorry.

    chakaping
    Free Member

    One of the many great things about Hope is that you can give them a bell and ask a friendly real person any random tech question you might have.

    Let us know what they say, just in case anyone else is searching for this in future.

    jhpbk
    Free Member

    Obviously Hope will know an awful lot better than me..

    But its my understanding that you’d need a 3mm offset chainring to make sure it worked correctly. Making your 52mm Chainline effectively 55mm

    They aren’t particularly expensive, but I suppose a tad annoying to add to the cost of a groupset.

    solarider
    Free Member

    It is important.

    The derailleur has a slightly bent and offset cage which helps with chain angles and relies on a 55mm chainline.

    In any case, if you purchase a full T-Type groupset you have no choice. The chainset comes with a longer DUB Wide crankset spindle and spacers out of the box which is 55mm by design.

    Your frame can’t ‘be 52mm’ as such. It has a standard width BB and standard rear spacing. It is the groupset (or more specifically the chainset) that really defines the chainline. Some bikes (my Yeti ARC as an example) require a 55mm chainline because the chain stays are spaced quite wide, so maybe the Hope 52mm thing might just be a statement that it doesn’t need wider spaced cranks to clear the stays.

    I am considering an Atherton and whilst the 150 and 130 both have a UDH, only the 130 will accept Transmission, with no plans for the 150 according to the conversation that I have had. It is (as somebody else has rightly pointed out) not a given than all UDH bikes will accept Transmission.

    I have Transmission on a couple of bikes and if you can fit it, you won’t regret it. It’s definitely next gen stuff.

    chrismac
    Full Member

    Apparently there are several versions of the udh and only some of them work with t type. No idea how you are meant to know if you have a compatible udh.

    Hob-Nob
    Free Member

    It is important

    I’m not sure it is.

    I’ve got it on one bike with a 55mm chainline, and another with a 52mm & they both shift fine (none with the SRAM crankset).

    solarider
    Free Member

    It will work of course. Transmission would be super finicky for 3mm to be a make or break difference, but it is designed to work with 55mm.

    From Sheldon Brown:

    How important is chainline?
     
    The worse the chainline, the worse the mechanical efficiency of the drive train, though research has shown the loss to be minor, at least with modern, flexible chains. “Correct” chainline for a derailer system is a matter of opinion, and depends on the intended use of the bicycle.

    sam1988
    Free Member

    Bit of a follow up. Having been in contact with both hope and SRAM. SRAm stay the transmission is designed around a 55mm chain line but works absolutely fine at 52mm.

    Hope mentioned the same but if I wanted to I could switch out to their “wide” axle. Anyways transmission ordered,

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