Anyone have experience with SRAM Eagle Transmission on any Specialized e-bike?

[mschwett]

I'm pretty sure that I listened to a podcast where a guy from SRAM explained the system in such a way that it somehow *does* know the position of the cassette and then moves the derailleur at just the right time to catch the ramps. I'll do some digging on this when I get a chance...

would love to hear that explanation, the tear down i watched didn’t suggest any such thing. how would they do it? an optical sensor and something about the one red cog? a magnetic sensor and an insert of some sort into the cassette? never seen any reference to this!

 

[dynamic]

would love to hear that explanation, the tear down i watched didn’t suggest any such thing. how would they do it? an optical sensor and something about the one red cog? a magnetic sensor and an insert of some sort into the cassette? never seen any reference to this!

I didn’t watch a tear down. But, if such a sensor exists, it would need to be internal and sealed off to survive the environmental aspects.

It doesn’t rule out other clever things. If it even has rotational speed of a cog, it should have a calculate-able window for the ramp locations. It wouldn’t take very much data to help. It also may be able to use successful shift timing to optimize future shifts. It definitely has some kind of accelerometer given these units can still retract on impact? Or was that only the axs version? A tension sensor could inform on timing of shift success. Etc. The electronics *could* be adding capability. Is it? No clue.

 

[mschwett]

I didn’t watch a tear down. But, if such a sensor exists, it would need to be internal and sealed off to survive the environmental aspects.

It doesn’t rule out other clever things. If it even has rotational speed of a cog, it should have a calculate-able window for the ramp locations. It wouldn’t take very much data to help. It also may be able to use successful shift timing to optimize future shifts. It definitely has some kind of accelerometer given these units can still retract on impact? Or was that only the axs version? A tension sensor could inform on timing of shift success. Etc. The electronics *could* be adding capability. Is it? No clue.

listen to this one around 14 min (and the rest, too) but it explains the key factor - the cogs are all even increments of two, allowing them to bring the "narrow-wide" technology that's been on chainrings for a while into the cassette, which essentially keeps the chain from shifting (the same way narrow wide up front keeps it from dropping!) until the cassette gets around to the desired spot for the transition.

Review: 1,000 Miles on SRAM's New Eagle Transmission - Pinkbike

After a ton of muddy miles, the verdict is...

www.pinkbike.com

and a good, clear english description, clearly stating the the RD mech isn't any different, but the cassette is designed to prevent the chain from moving over when they don't want it to. no electrical sorcery.

In principle, the basic function of the new Eagle Transmission derailleur isn’t much unlike that of previous AXS models. The all-new derailleur nudges the chain inwards or outwards, depending on whether you want to shift up or down. The cassette does the actual work. Cassettes have long had so-called shifting ramps, which look like recesses on the sides of the cogs, and they’re there to help the chain climb onto a bigger cog when shifting up.

SRAM also rely on shifting ramps for their new Eagle Transmission cassettes. However, this is less of an aid and much more of a determinant for when the chain shifts. The chain won’t shift gears without the help of a shifting ramp. Depending on the gear, the new Transmission cassette has a different number of shifting ramps, which are responsible for shifting either up or down. SRAM also rely on many other practical features to optimise the shifting process. The sprockets of the new Eagle Transmission cassettes utilise the narrow-wide design, with alternating narrow and wide teeth. Until now, it was only the three inner cogs of SRAM cassettes that had narrow-wide teeth. In addition, the new Flattop chain can only mesh with the cassette in a certain position, ensuring that it is always perfectly engaged and distributing the pedalling forces equally. If it does end up in the wrong position, it won’t mesh with the cog and will simply slip back into the correct position as soon as you apply a light load. Due to the omission of the B screw, the distance between the upper guide pulley and the cassette is always correct, too.

If you shift just one gear, the alignment between the derailleur and the cassette requires the derailleur to move only to such an extent that the chain uses a single shift lane to jump up or down the cassette, preventing it from being forced into the wrong gear. The best part comes with shifting several gears at once, because the new Transmission derailleur has a programmed delay between shifting operations. For example, if you shift two or three gears in quick succession, the derailleur won’t move at the same speed but rather time the shifting. This allows the chain to wait for a shifting ramp on the cassette instead of being forced up or down the cassette.

what's very cool about all this is that it's really a complete system, and they redesigned each part in small ways to make the whole way more than the sum of the parts : the UDH provides the necessary stiffness and alignment. the flat-top chain only interfaces with the cogs in the correct even-odd pattern. the cassette tooling is much more aggressive, resulting in a chain-cassette interface where the chain CAN'T move over unless it's at a certain spot, and the RD mech has a strong motor and the delay feature to make multiple shifts stay aligned.

i read/watched about 5 long term reviews, install, teardowns, and not a single one mentions any sort of sensors or requirement for the RD to know at what point in the rotation the cassette is. it's all described generally the same way, but with vague language that could allow one to infer that the RD actually "knows" where the cassette is in rotation. but it doesn't. because it doesn't need to. that's what makes it a good design.

 

[dynamic]

but with vague language that could allow one to infer that the RD actually "knows" where the cassette is in rotation. but it doesn't. because it doesn't need to. that's what makes it a good design.

And now I love it even more.

 

[mschwett]

this discussion and watching the videos got me thinking... how do i really shift, and how big of a difference is this!??!

i went out for a sprint up and down the street with a selfie stick and realized that 1) i don't let up or stop pedaling at all when shifting, except in the most extreme circumstances (out of the saddle, standing on the pedals with all my force) and 2) shimano's latest shifts insanely fast, under load or not. sram transmission definitely doesn't shift faster than this - but my guess is that it IS much more robust if one were to truly abuse it off road. unfortunately the tech is not suited to road groupsets, so we may continue to see the same divergence of sram having an edge off road and shimano on road.

i'm pedaling from around 200 to 500 watts here - more power than an SL motor for sure - and of course what you can't tell is how long the delay is from pushing the button to the shift initiation. my perception is that that delay is essentially zero. for all practical purposes it's instantaneous. these things have come a long way.

 

[maldororrising]

Just created an account to chime in here.
I have a Turbo Tero X 6.0 and ordered a Sram X0 t-type setup for ebikes (part # 00.7918.281.002) a couple days ago. The only difference with the ebike specific version is that it comes with a 104bcd chainring and no crank arm). Regarding XD vs HG freehub, I spoke with Specialized customer support and it is a typo and that we do indeed have a XD hub.

 

[dynamic]

Just created an account to chime in here.
I have a Turbo Tero X 6.0 and ordered a Sram X0 t-type setup for Ebikes (part # 00.7918.281.002) a couple days ago. The only difference between the ebike specific version is that it comes with a 104bcd chainring and no crankarm). Regarding XD vs HG freehub, I spoke with Specialized customer support and it is typo and that we do indeed have a XD hub.

Report back how it works! I am thinking of ordering a tero x 6.0 and the gx eagle transmission.

 

[Ben J]

Another interesting experiment would be to see if the hard wired power option for AXS can be made to work with a Specialized bike. The Trek FS 9 EQ has that setup, which seemed appealing to me compared to having one more rechargeable thing to charge.

 

[maldororrising]

Just an update. I had the X0 Transmission installed onto my Turbo Tero X 6.0 and it rides beautifully. Shifting gears while pedaling up a steep hill is pretty nice. The shifts are clean and I haven't really noticed any significant delays like in some of the online reviews. The MPN is 00.7918.281.002 (everything needed besides crank arms).

 

[Ben J]

Just an update. I had the X0 Transmission installed onto my Turbo Tero X 6.0 and it rides beautifully. Shifting gears while pedaling up a steep hill is pretty nice. The shifts are clean and I haven't really noticed any significant delays like in some of the online reviews. The MPN is 00.7918.281.002 (everything needed besides crank arms).

Did you pair it to the bike? I know the bike can display which gear you're in, but I've been curious to know if it does anything else.

 

[maldororrising]

You mean to the TCD? I didn't even know that is possible. I'll look into it.

 

[Ben J]

You mean to the TCD? I didn't even know that is possible. I'll look into it.

If you watch this video about pairing a RADAR, when you get to this screen:

you'll also see "SHIFTING" (not in the video, but on your bike)

 

[maldororrising]

If you watch this video about pairing a RADAR, when you get to this screen:

you'll also see "SHIFTING" (not in the video, but on your bike)

I know you can pair the radar to it, but I didn't see any mention of pairing the AXS shifter to it. I'll look to see if you can pair those together.

 

[dynamic]

I was prepared to pull the trigger on the tero X 6.0 + gx eagle transmission (or possibly X0), but the flooding here destroyed just about every first floor business in downtown. Including the bike shop. It's going to be months before they are functional again. I believe this is officially a "next year" thing.

 

[maldororrising]

If you watch this video about pairing a RADAR, when you get to this screen:

you'll also see "SHIFTING" (not in the video, but on your bike)

Finally figured it out and was able to pair AXS to the bike screen. The RD battery % and current selected gear both show up.

 

[dynamic]

And now it’s a year later. Most things have recovered from the flood, some by moving to a new location. Both local bike shops have moved to new locations and are functional. Yay.

Anyone else have more feedback on the tero x + transmission?

I am also considering the trek fuel eXe as it has multiple models that come with transmission installed. And I love the idea of a lighter fun bike, given how much I love my Sirrus X 4.0.

 

[Prairie Dog]

I swapped out the stock tranny for the entry level GX T-type drivetrain on my Epic Evo and haven’t regretted it since doing so several weeks ago. Acquiring one at almost ½ the price was reason enough to pull the trigger. Apparently, the seller’s bike was not UDH compatible. The only niggle that I would have with it might be a slight delay in shifting compared to a traditional top tier drivetrain as the derailleur waits for a shifting ramp on the cassette instead of forcing the chain up the cogs. However, that minor drawback certainly didn’t affect me on the trails as the ultimate benefit was never having to bother backing off my pedaling load, at all, ever.



A faint electronic ‘blip’ and perhaps a slight clunk during shifts were the only perceptible noises. No mashing of gears on steep climbs and on many occasions, I never prepared myself in time for gear changes when the terrain suddenly became steeper. That’s how good it is.

The GX doesn’t have the magic pulley found on either the XX or X0 where the lower jockey wheel continues to spin independently if debris happens to get caught up internally.

 

[Grueso]

So, is this SRAM Eagle Transmission better (by that I mean, faster & smoother under full power) than Shimano Hyperglide+? I have a Hyperglide cassette, not Hyperglide+, and I thought that already reduced the crunch (when shifting under load) considerably compared to what I remember from drivetrains of yore.
Shimano uses this graph to advertise the smoother and faster Hyperglide+ shifting:

Is this more a mountain bike than a road bike thing, i.e. important only when a sudden steep incline catches you by surprise in the wrong gear?

Also, I must say the UDH reference is a bit confusing. This new (well, new last year) SRAM derailleur does NOT use the UDH hanger, it takes the place of the UDH, so it needs a frame that is compatible with UDH.
(From the SRAM web page: "It uses no derailleur hanger or adjustment screws and lets you shift flawlessly under maximum power.")

 

[Prairie Dog]

So, is this SRAM Eagle Transmission better (by that I mean, faster & smoother under full power) than Shimano Hyperglide+? I have a Hyperglide cassette, not Hyperglide+, and I thought that already reduced the crunch (when shifting under load) considerably compared to what I remember from drivetrains of yore.
Shimano uses this graph to advertise the smoother and faster Hyperglide+ shifting:
View attachment 179177

Is this more a mountain bike than a road bike thing, i.e. important only when a sudden steep incline catches you by surprise in the wrong gear?

Also, I must say the UDH reference is a bit confusing. This new (well, new last year) SRAM derailleur does NOT use the UDH hanger, it takes the place of the UDH, so it needs a frame that is compatible with UDH.
(From the SRAM web page: "It uses no derailleur hanger or adjustment screws and lets you shift flawlessly under maximum power.")

SRAM have been working behind the scenes for a while now developing the UDH specifically for mtbs and getting manufacturers to adopt the standard. There are currently over 200 models of mountain bikes that now rely on the UDH.



Here’s where I think the T-Type drivetrain excels. If omitting the hanger interface and putting an end to limit screws and gap settings or always having the cassette and derailleur perfectly aligned the moment it’s installed, or allowing you to continue pedaling while under full load or being able to microtune from the AXS app or pod shifter then I would tend to agree that it is better in those respects. Since the RD is also modular in design parts can be interchanged in the rare event the robust derailleur gets damaged in a crash.

It will be interesting to see if SRAM is able to get the standard better established in other disciplines including the gravel scene and whether or not builders choose to adopt it. From what I understand there are very few brands that offer frames with compatible dropouts. I suppose for now it might be up to those in niche markets to advance the sales of a few unique and exclusive bikes..

Shafer Gravel Bike Now Compatible with SRAM Transmission

Sram transmission benefits on a gravel bike Not many gravel bikes are UDH (Universal Derailleur Hanger) compatible right now. The improved range and reliability of the T-type SRAM Transmission is beneficial not only for mountain biking, but also gravel riding. Gravel bikes versatility on...

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SRAM UDH & Transmission Compatibility is here.

SRAM UDH compatibility is now an option on our GT-1 45, GT-1X and made-to-order GT-2 45, GT-2 X and MT-2 framesets.

www.mosaiccycles.com

 

[mschwett]

…It will be interesting to see if SRAM is able to get the standard better established in other disciplines including the gravel scene and whether or not builders choose to adopt it. From what I understand there are very few brands that offer frames with compatible dropouts. I suppose for now it might be up to those in niche markets to advance the sales of a few unique and exclusive bikes..

trek putting UDH on their latest madone (which replaces both the previous emonda and madone) is an interesting sign.

i haven’t ridden a “transmission” bike but i’m having a hard time understanding how it could be much better than the latest shimano 12 speed electronic groups with hyperglide+ or whatever it is that already shift more or less instantly and quietly under load.

mechanically UDH does seem like a big improvement.