Keywords: 27.5,700c,assembly,gravel ride,sram etap,tire clearance

eTap on Gravel(Plus) bikes

Gerard Vroomen - 05-Jan-2017
With some regularity I get asked if eTap fits on the U.P.. The answer is yes.

Of course that wouldn't be worth its own OPEN Update if there wasn't more to the story, so here it goes. eTap fits on the frame no problem, the bike will shift flawlessly and you'll be very happy. Except eTap poses one big limitation: the way the battery is positioned on the front derailleur, it sits quite close to the rear tire. 

To be exact, according to SRAM's tech documentation the clearance from the center plane of the wheel to the inside face of the battery is 20.1mm. If you adhere to the 6mm tire clearance mandated by some rules, that would mean your maximum tire diameter is 28.2mm (2x(20.1-6.0)) or in other words, a standard road tire. 

But it seems that SRAM's information is not very accurate, plenty people have assembled 35 and even 40mm tires on an OPEN with eTap, so the official information is off by quite a bit. Partially that's because people decide to flaunt that 6mm rule (I do all the time but of course, I'm irresponsible and I wouldn't want you to end up being like me so "don't try this at home").

So while eTap is completely compatible with the U.P. frame, it's not compatible up to that maximum tire that it can fit. So no possibility for 650Bx47 RoadPlus tires and 650Bx2.0" or even larger GravelPlus set-ups.

There's nothing we can do about it, it has nothing to do with the frame. This is baked into the eTap front derailleur design and applies to any frame you put it on.

You may think to get clever and turn the bike into 1x eTap since the front derailleur then becomes obsolete, but unfortunately the eTap rear derailleur doesn't have a clutch so you would need to figure out something to avoid losing your chain. A small guide is of course an option, and you do have the front derailleur mount available to attach it.

If anybody has done anything creative in this regard, I'd love to see it so let me know.

Comments & Questions

This has been done by an online magazine and he report same as you say.
The 35mm tire are hairs away from the Etap FD battery.
Beyond me why anyone would fit Etap on the UP with this in mind.
Risk is probably that a tire pick up dirt, debris or such and the FD get damaged.
I run a Panaracer GK SK 700*40 and the guy i spoke of did use the 35mm version in his test.
My Gravel King SK 700*40 has gnawed off paint at the seat mast tube.
This has been happening in late season when tires has been packed with dirt.
So what i mean is, this might happen with a tire using Etap FD to.
Just saying...
Post #1 of 34. Posted by Rird on 05-Jan-2017 17:37:21 GMT in reply to blog [0<--1300]
Hi ! Very interesting.
Just to clarify, what do you mean by "doesn't have a clutch"

Post #2 of 34. Posted by Jérôme WALRAVE on 05-Jan-2017 17:38:50 GMT in reply to blog [0<--1301]
Doesn't have a clutch like SRAM and Shimano clutch derailleurs that allow for use of a 1x.
Post #3 of 34. Posted by Noah on 05-Jan-2017 19:25:43 GMT in reply to post #2 [1301<--1302]
As Noah mentioned, both XTR and Force 1 rear derailleurs have a clutch and extra spring tension to prevent the chain from popping off the chainring (on a 2x, the front derailleur prevents this in most cases). So if you use a 2x rear derailleur such as eTap on a 1x set-up, you don't have the front derailleur nor the clutch and extra spring tension to prevent losing the chain off the chainring.
Post #13 of 34. Posted by Gerard Vroomen on 07-Jan-2017 10:48:34 GMT in reply to post #2 [1301<--1313]
Ok thanks i got it now.
Post #19 of 34. Posted by Jérôme WALRAVE on 09-Jan-2017 16:05:43 GMT in reply to post #13 [1313<--1328]
I have spaced the derailleur adapter out on an Ultegra Di2 install to shift a road crank with mtb chainline spider. Shifts fine on the stand but not ride tested. This might give enough clearance for eTap but my plan is to make an adapter that will position an XT Di2 FD low enough for 42/28 chainrings and 11-40 cassette.
Post #4 of 34. Posted by Peter. on 05-Jan-2017 22:31:04 GMT in reply to blog [0<--1303]
Hi Gerard.
would a repackaging the battery work? or would the mount still get in the way.
Ie put the battery above the derailer or below the bottle cage ,with a wire to the mounting /contact part.
Would need to be re-encased in resin or plastidip. Obviously safety, warranty, charging and fire, injury and possible death issues aside.
Post #5 of 34. Posted by Glen Hamilton on 06-Jan-2017 01:23:14 GMT in reply to blog [0<--1304]
here is a picture with tyres listed below . My crazy idea might work!!
gap between the Panaracer Gravelking 700c x 35mm tyre (which measure 38mm fitted to American Classic’s Hurricane wheelset)
Post #6 of 34. Posted by Glen Hamilton on 06-Jan-2017 01:30:20 GMT in reply to post #5 [1304<--1305]
Yes, death issues aside. I am sure SRAM will fix this issue, although I don't think it will be too soon. They really seem to focus on SRAM Eagle and the mountain bike range for right now.
Post #12 of 34. Posted by Gerard Vroomen on 07-Jan-2017 10:45:37 GMT in reply to post #5 [1304<--1312]
My LBS is currently converting my UP from Ultegra 2x11 to 1x11 Di2. We looked into eTap, but decided on a mash up of Easton chainset (v. light!) and XTR rear mech to give good gear range - and clutch mech. I'd got wanted to drop some weight off the bike, and I was fed up of dropping the chain w Ultegra 2x set up - frame has some grim gouges out of it down at the BB area. Not pretty.
Post #7 of 34. Posted by Richard Wilson on 06-Jan-2017 03:49:47 GMT in reply to blog [0<--1306]
Paint is scratched and chipped (110 bcd and smaller spiders and dropped chains) on my BB too, I've yet to really ride it. The Easton is on my list, chainlines of 43.5/46/47 for road/disk/1x. Chainline for XT/R FD is 48.8, so 1x ring is close. I hope I can fit a Race Face mountain axle and spider to the Easton arms, axle will increase Q but shouldn't be as wide as a mountain crankset and extra clearance from the evo386 bb is probably needed. An 11-46 cassette is getting close to the range of a mountain double. Very interested to hear how you get on, good luck!
Post #8 of 34. Posted by Peter on 06-Jan-2017 17:24:20 GMT in reply to post #7 [1306<--1307]
... a bdop R135-11 hub will provide a 130 road chainline in a 135 O.L.D disc hub, Ultegra Di2 will reach in far enough to the big cog with adjustment set to -12 on an XTR display. Ultegra will work 1x too, RoadLink is OK for bigger cassettes. Getting chainline right is probably more important with 1x, the R135-11 might help.
Post #9 of 34. Posted by Peter on 06-Jan-2017 19:53:49 GMT in reply to post #8 [1307<--1308]
I don't think it's worth going to a different rear hub. For 1x it's very simple to get the right chainline, just use the outer ring position on a 2x crank. Or in the case of a Force1 crank (which is the same as a Force 2x crank with different logo), just switch the offset ring (which puts it back at the wrong 43.5mm chainline) for a flat ring and you're set. NOTE: newer Force1 cranks seem to have a bigger chainline dimension so then this is no longer necessary.

Furthermore, chainline is actually not as big an issue as people think, modern 1x11 set-ups will shift fine with the chainring in roughly a +/- 3mm range. This is also why the offset Force1 rings still shift fine on the UP, because although not perfectly in the middle of the cassette, it's still close enough.
Post #10 of 34. Posted by Gerard Vroomen on 07-Jan-2017 10:41:37 GMT in reply to post #9 [1308<--1310]
Hi Gerard, thanks for your comments on 1x and chainline. I agree, a 130 spaced hub for 1x doesn't make much sense but behind a double it shifts nicely, also my chain doesn't get picked up by the big ring's ramps and get hooked into the bb when cross'd (94 bcd 46/30 super compact). After months of trying to configure a drivetrain that matches the UP's range I've concluded it can't be in one, in the way I want. This is a good thing rather than a disappointment, I'm reluctantly accepting Shimano's separation of road and mountain could be more than a marketing convenience. So, road tyres, road drivetrain, mountain tyres, mountain drivetrain. Di2 makes it an easy swap. Thanks for the challenge and a very nice bike.
Post #14 of 34. Posted by Peter on 07-Jan-2017 19:56:03 GMT in reply to post #10 [1310<--1314]
Thanks for your comments. BTW I'm not sure I agree with your comment on Shimano's separation, after all I run Di2 road shift/brake levers in combination with XTR rear derailleur and disc brakes on my U.P.! (See the May 2016 Bike Of The Month gallery on the U.P. page.
Post #15 of 34. Posted by Gerard Vroomen on 08-Jan-2017 17:42:12 GMT in reply to post #14 [1314<--1315]
Yes, at least Shimano have given us that, drop bar mountain double too :-).
Post #16 of 34. Posted by Peter on 08-Jan-2017 21:07:57 GMT in reply to post #15 [1315<--1316]
But that only works with a mountain bike, or at least with a mountainbike front derailleur and therefore mtb crank and Q-factor. Front and rear derailleur have to be of the same type (road or mtb), the shifter can be different.
Post #17 of 34. Posted by Gerard Vroomen on 08-Jan-2017 22:21:35 GMT in reply to post #16 [1316<--1317]
Yes, it does require a mountain FD but not a mountain crank, just a mountain chainline. Works nicely on a 'cross bike with 41/26, road crank and Q-factor. 15t is about the limit on the 10t spec'd XTR though, and that will probably drop as the rings get bigger. About to install on a T47 road plus frame, should be here tomorrow.
Post #18 of 34. Posted by Peter on 09-Jan-2017 00:15:57 GMT in reply to post #17 [1317<--1318]
Yep, 1x11 XTR Di2 works great, that's still on my U.P. XTR brakes are fantastic too. And when you have the 1x Di2 set-up, you can also reprogram your buttons so that the left lever buttons aren't completely obsolete. You can for example program both left lever buttons to cause an upshift and both right lever buttons to cause a downshift. Fun and games.
Post #11 of 34. Posted by Gerard Vroomen on 07-Jan-2017 10:44:23 GMT in reply to post #7 [1306<--1311]
Gerard, I am looking to do this on a current build, Di2 and 1x with Easton Crankset. Is this done with the Shimano Phone App? Thanks.
Post #24 of 34. Posted by matt on 11-Feb-2018 17:25:38 GMT in reply to post #11 [1311<--10499]
I'm not sure, I don't have experience with the phone app. Some googling might be required.
Post #25 of 34. Posted by Gerard Vroomen on 11-Feb-2018 17:56:49 GMT in reply to post #24 [10499<--10500]
I've got a solution to reduce the clearance problem with eTap. I've done this on my bike. Put a spacer between the frame and FD hanger. I used 3mm plastic (LDPE). I cut the plastic to the same footprint as the hanger, and drilled holes for the hanger mounting screws. My spacer was just thick enough to allow removing BOTH limit screws. That is, the spacer pushed the FD away from the frame just enough that the lower limit screw is no longer necessary. Further, the eTap FD high limit screw is reverse threaded. That means that when you set it at the minimum travel limit (turned clockwise), the screw is all the way out. This is important, because the limit screws will otherwise interfere with the crank. When done, I added about 3mm clearance to the drive side of the tire. There is about 3mm clearance between the crank arm and FD body, and 4.5mm tire clearance to the FD with tires that measure 39.5mm. There is really not much more clearance to the seat tube; so I think I have effectively created all the tire clearance I want. Note that I am running a full SRAM drivetrain and Quark power meter. If you use different components (chainrings, crank, chain), you may need to use the high limit screw, but you may grind it down to allow inserting it far enough to not interfere with the crank.
Post #20 of 34. Posted by Paul Dunn on 07-Mar-2017 16:42:02 GMT in reply to blog [0<--1580]
That's a clever solution. It also should be said (as you sort of found out in your measurements too) that even in the standard set-up, you can fit bigger tires next to the front derailleur than SRAM indicates. But of course, it all depends on the clearance you're comfortable with.
Post #21 of 34. Posted by Gerard Vroomen on 08-Mar-2017 16:28:01 GMT in reply to post #20 [1580<--1582]
Using the same setup (eTap WiFLi 50/34x11-32, mechanical brakes, DZero), but 5mm plastic spacer. Without FD limit screws. With WTB Rsolute 700cx42 tires, which measures 43.5mm at 60psi. FD-to-tire clearance 4-5mm. Crank-to-FD clearance 2mm.
BTW, 11-36 cassette also compatible without any issues.
Post #22 of 34. Posted by Dat on 21-Sep-2017 03:52:01 GMT in reply to post #20 [1580<--7076]
Definitely fit is better than the official SRAM information indicates. Without much trouble 40mm tires can fit, and as you note with some tweaks even more.
Post #23 of 34. Posted by Gerard Vroomen on 30-Sep-2017 18:17:15 GMT in reply to post #22 [7076<--7114]
This is very interesting/encouraging. I’m currently specing our a build on a size small frame with eTap groupset (WiFLi 50/34x11-32). I was hoping to use Zipp 303 650b with 47mm tires like Compass Switchback Hill TC... but then I started reading about these spacing issues. So I might have to ditch 650b and go with 700c & 40mm tires. Do you happen to have any photos of this setup with spacer/screw adjustments? I keep hoping SRAM announces some magical new eTap setup this year but I can’t really wait for something that might never come.
Post #26 of 34. Posted by nuzz on 23-Jun-2018 01:01:59 GMT in reply to post #22 [7076<--13848]
Great tips as I just went with eTap on my gravel bike (sorry, not an Open frame given my height). The spacer advice will be on my to-do for wrenching this weekend.
Post #27 of 34. Posted by Todd on 24-Aug-2018 13:21:41 GMT in reply to post #26 [13848<--13959]
Great idea.Could you share some photos of your hack.Would be really helpful.Thanks in advance
Post #30 of 34. Posted by vivek on 15-Feb-2019 17:27:23 GMT in reply to post #22 [7076<--18271]
This is exactly what I am trying. I was wondering if a spacer to the crank will help in giving some space adding a spacer safely to the frame and FD hanger. I have not really replaced a crank ,but that was my thought. Is it possible ? I have a sram red crankset.
Post #34 of 34. Posted by vivek on 26-May-2023 20:51:32 GMT in reply to post #20 [1580<--24798]
Gerard - Have you seen anyone stich together a reliable 1x Etap configuration?
Post #28 of 34. Posted by JL on 18-Sep-2018 23:44:35 GMT in reply to blog [0<--14996]
Well it must have something to do with frame design as we are using 650b x 40 Schwalbe G-one speed tyres and we have a 28mm gap between the battery and the tyre.
We using 50/34 at he front and an 11-42 with eTap WiFli and a Wolftooth Roadlink on our Co-motion tandem
Post #29 of 34. Posted by Geoff on 23-Jan-2019 06:37:36 GMT in reply to blog [0<--18196]
You have a nice big gap because you're using 650b. You wouldn't have that same gap with a 700c setup
Post #31 of 34. Posted by Erik on 01-Apr-2019 12:00:35 GMT in reply to post #29 [18196<--18334]
I've successfully used SRAM eTap on a Volagi Viaje (415mm chain stay length) with 40mm wide 700C tires as well as WTB Horizons (650Bx47). Between the front derailleur battery and the Horizon tire there's about 1cm clearance. There was less with a 700C wheel, but enough for road use. The Open UP has 420mm chain stays. Rather than using a spacer like Paul Dunn mentioned, one could also look at repositioning the derailleur forward (and up) with a custom bolt-on hanger. SRAM's frame fit spec for instance gives a fixation bolt position of 141mm from BB center for 50/34 chainrings and a 61-66° braze-on hanger angle. 5° to remain within spec is quite a lot. Taking a radius of 141mm it's about 12mm. Since the Open UP uses a bolt-on FD hanger, it'd be worth looking into it.
Post #32 of 34. Posted by Patrick Strahm on 29-Apr-2019 08:11:11 GMT in reply to post #29 [18196<--18370]
I get 5mm clearance between the Red eTap FD battery and a 700x35mm (measured width) tyre on an Open UPPER. So I could probably fit 40mm wide tyre and still have a couple of mm clearance. Photo here: https://photos....TPAXA
Post #33 of 34. Posted by Nick Payne on 21-May-2020 08:40:16 GMT in reply to blog [0<--22239]