SRAM eTap with Shimano Crank?

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  • October 6, 2016 at 3:11 am #1056070
    hozn
    Participant

    Apparently (according to the forums, anyway) you can use a 30t or 32t cog with eTap.

    Not sure I understand what the Shimano crank is getting you here. The 110BCD Sram crank is a compact crank which means you can use 34/50 (or 36/52) — or 39/53 if you get the Praxis “standard-but-fits-on-compact” rings. A 34t ring with a 30t or 32t cog sounds like a pretty low gear for any sort of race situation. 34:28 was plenty low for Garrett County Gran Fondo in my experience.

    Perhaps you meant 130BCD SRAM crankset? Yeah, I have no idea why anyone would buy a standard crank these days when 36:52 fits on a compact crankset and even 50:11 is a taller gear than 53:12.

    October 6, 2016 at 12:32 pm #1056063
    vvill
    Participant

    I think I’d agree with hozn and just go with 52/36 instead of changing out a crankset just to be able to use 53/39.

    But if you really want a 53, there’s at least one third party company that make SRAM compatible 110BCD chainrings in 53T, e.g.:
    https://wickwerks.com/products/road-bike-ultra-wide-53-34/

    October 6, 2016 at 6:58 pm #1056022
    rhfritz
    Participant

    Interesting. I’ve seen a few posts but not about eTap indicating you can sometimes run a 30T on a short cage if you adjust the B screw. Others have indicated it’s not possible with eTap.
    A 130BCD SRAM crankset is the only one that has 53/39. Their 110BCD starts smaller. But, yes, if I could go larger than 28T, I’d be less concerned about only 34T in the front.

    A bike shop responded to my inquiry with:

    “I talked to SRAM this morning and they mentioned eTap was designed and tested for use with SRAM Red 22 Cranks and Chain. The issue is the Crank ramps as they are designed around the SRAM Red Chain. I asked them about using other cranks, and it was mentioned to me use of the product out of the intended design could void the warranty.

    Bottom line is it will work with other cranks, but not as well as it was designed.”

    In my view this response avoids my question because, while I understand the whole “ramps” issue, all the derailleur does is push the chain in a direction. And unless I’m mistaken, it has nothing that engages the chain like a ramp. But a 3rd party ring on a SRAM crank as also suggested might fit the “not as well” criteria which I understand might mean “noisy” or not as smooth shifting.

    And my interest in this arrangement is simply that I’m used to 53/39 which is fine for my typical race. My plan is to do SavageMan 70 next year — also in Garrett County. If you see here: https://www.vtsmts.com/savageman-elevation-profiles/ you’ll see that Westernport averages 12% but has a segment that’s 31%. Climbing that looks like this: https://www.youtube.com/watch?v=E3Hv1v9gE_w

    So being able to switch rings to something with 34T or less would be helpful.

    October 6, 2016 at 7:04 pm #1056018
    Tim Kelley
    Participant

    @rhfritz 147050 wrote:

    My plan is to do SavageMan next year. If you see here: https://www.vtsmts.com/savageman-elevation-profiles/ you’ll see that Westernport averages 12% but has a segment that’s 31%. Climbing that looks like this: https://www.youtube.com/watch?v=E3Hv1v9gE_w

    So being able to switch rings to something with 34 would be helpful.

    If you haven’t been out to Westernport yet to scope things out, the wall is one thing, but it’s everything after the wall that you just have a grind through that will make you want a 34…

    October 6, 2016 at 7:08 pm #1056019
    TwoWheelsDC
    Participant

    @vvill 146989 wrote:

    I think I’d agree with hozn and just go with 52/36 instead of changing out a crankset just to be able to use 53/39.

    But if you really want a 53, there’s at least one third party company that make SRAM compatible 110BCD chainrings in 53T, e.g.:
    https://wickwerks.com/products/road-bike-ultra-wide-53-34/

    Rotor makes 110bcd 53t chainrings as well (one is currently en route to my house, as it turns out…).

    October 6, 2016 at 7:16 pm #1056014
    rhfritz
    Participant

    @Tim Kelley 147052 wrote:

    If you haven’t been out to Westernport yet to scope things out, the wall is one thing, but it’s everything after the wall that you just have a grind through that will make you want a 34…

    I did the SavageMan 50 this past Sept. 17th. And I did drive out Westernport. But it was the climbs I did with my 39/28 that told me that I’ll need something more next year. :-)

    October 6, 2016 at 7:48 pm #1056010
    hozn
    Participant

    Yeah, we took a detour from the DD to do the wall. I would prefer a 34t ring for that ride for sure, though a 36t ring with a 30t cog would be even easier.

    The short answer is that I assume the Shimano crank would work fine, but given the availability of third-party 39/53 ring sets for 110BCD crank sets, there is no reason to go Shimano. Plus the Red crank will be much lighter.

    October 7, 2016 at 3:06 am #1058678
    rhfritz
    Participant

    A guy here https://forums.cervelo.com/forums/p/16130/108200.aspx
    indicates he’s running an eTap with 11-32T cassette

    and also some here:
    http://weightweenies.starbike.com/forum/viewtopic.php?f=3&t=139404&sid=bc43883124b0537ba2ba47a7cf22d580

    October 7, 2016 at 3:20 pm #1058689
    vvill
    Participant

    @rhfritz 147050 wrote:

    In my view this response avoids my question because, while I understand the whole “ramps” issue, all the derailleur does is push the chain in a direction. And unless I’m mistaken, it has nothing that engages the chain like a ramp. But a 3rd party ring on a SRAM crank as also suggested might fit the “not as well” criteria which I understand might mean “noisy” or not as smooth shifting.

    I’d assume they’re talking about shifting from the small to large chainring where the chain catches onto pins on the inside of the large chainring and sort of “slides” on ramps to get onto the big ring. Scroll down to “Ramped and Pinned” here http://www.sheldonbrown.com/gloss_ra-e.html

    October 7, 2016 at 5:49 pm #1058694
    hozn
    Participant

    @rhfritz 147050 wrote:

    But a 3rd party ring on a SRAM crank as also suggested might fit the “not as well” criteria which I understand might mean “noisy” or not as smooth shifting.

    In my (limited) experience, going 3rd party doesn’t necessarily mean it won’t shift as well. Swapping to Praxis rings on my (SRAM) crankset made a very noticeable improvement in the speed of front shifts vs the standard SRAM Red 36/52 setup I was running before. I was mistaken about Praxis making 39/53 for 110BCD, though; I must have been thinking of the Wickwerks ones vvill mentoined.

    October 8, 2016 at 12:39 am #1058699
    hozn
    Participant

    Also, it sounds like eTap wifli is just (a couple?) months away.

    http://www.bikerumor.com/2016/10/07/wifli-coming-sram-red-etap-soon-rim-disc-brakes/

    October 8, 2016 at 5:02 pm #1058704
    rhfritz
    Participant

    Odd that there’s nothing at the SRAM site, but it does look like eTap wifli is due to be out in December 2016:

    http://www.cxmagazine.com/sram-red-etap-wifli-rear-derailleur-expands-range

    So is “weight savings” the primary reason the short cage is standard? Or are there any other disadvantages associated with a long cage?

    And the Wikwerks 53/34 is intriguing. https://wickwerks.com/products/road-bike-ultra-wide-53-34/

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