SRAM eTap with Shimano Crank?

[rhfritz]

I know that SRAM & Shimano would prefer that you not mix their groups, but is anyone running an eTap with a Shimano or other non-Red crank?

Here’s my rationale for wanting to mix:
I’ve got a Cannondale Slice tri-bike setup with the 10-speed S105 groupset, 53/39 in front; typically 12-23 in back, but 11-28 for climbing due to short cage limitation. I’d like to upgrade to SRAM eTap aero and am planning to race on a course with 6000ft of steep climbs next year. I know eTap doesn’t have wifli, and I’d like to achieve a little more shifting range than the SRAM Red 110 BCD crankset allows.

If I understand correctly, the new Shimano cranks are using a 110 BCD and are able to be compatible with 50/34, 52/36, and 53/39. So as long as I keep the crank, chain, and cassette as 11-speed Shimano, why couldn’t I match that group with the eTap? That way I could keep my 53/39 + 12/23 equivalent for my normal races but have access to a 50/34 + 11-28 for climbing. I’m currently giving heavy consideration to the Shimano 6800 ultegra crank. Any recommendations appreciated.

Topic

[hozn]

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.

[vvill]

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/

[rhfritz]

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.

[Tim Kelley]

@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…

[TwoWheelsDC]

@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…).

[rhfritz]

@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.

[hozn]

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.

[rhfritz]

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

[vvill]

@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

[hozn]

@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.

[hozn]

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/

[rhfritz]

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/

[Author]

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