SRAM Eagle Shifting Problem

I’ve been trying to diagnose a serious SRAM Eagle shifting problem with my XX1 Eagle drive-train that no shop or SRAM is able of diagnosing or fixing, and I’m close to concluding that SRAM Eagle has a serious design flaw.

SRAM Eagle Shifting Problem
Desynchronized chain riding on top of 42t and 50t sprocket

I bought a new 2017 Trek Fuel Ex 9.9 in May and the lower two gears have been crunchy since I rode out the shop. The bike has never been crashed nor has it fallen over. All the basics have been checked, derailleur hanger alignment, chain length, cable routing, kinks in the cable, and proper derailleur alignment was done several times using the red plastic SRAM b-alignment tool (with the shock compressed for sag). No matter how much fiddling, no amount of adjustment is able to prevent the occasional misshift when downshifting to the 42t and 50t sprockets.

Misshift is a mild way of putting it. On a bike stand, shifting from 3rd, to 2nd and 1st gears, the chain will often end up riding on TOP of the sprocket teeth and stay there. Out on the trail, the same thing happens momentarily before the torque from the pedal stroke violently pulls and drags the chain OVER the entire sprocket moving it forward by 1 tooth before it settles into place. It’s actually hard to see this while it’s happening but this is what’s going on when you hear those nasty klunks on those two larger gears.

Reviews online are overwhelmingly positive and read more like press releases, but a few reviews have hinted at the problem.

MTBR mentions :

“an occasional pop in the rear cassette and chain”

but never goes into detail about it .

Singletracks.com also hints at it:

“At one point, I did get the drivetrain to squawk at me: when accelerating out of the saddle, up out of a mud hole, on a stupid-steep hill, and attempting to downshift three gears at once. Ultimately it was a bad call on my part, and while the drivetrain crackled and groaned under pressure and from grit in the gears”

Pinkbike also hints at the problem but completely minimizes it :

“The eight-tooth jump from the 42- to the 50-tooth cogs did sometimes sound a little louder than the other shifts, but the chain always ended up exactly where it was supposed to be, even when shifting on a steep uphill. That jump between those final two gears didn’t bother me out on the trail, although it may take time for riders that are more particular about their cadence to get used to it. As I mentioned, I typically used that cog as a bailout, a last ditch effort to keep my momentum on tricky climbs”

Pinkbike even has a picture of their bike with the chain riding on top of the spocket…

SRAM Eagle Shifting Problem
Pinkbike’s review bike showing the desynchronized chain

After a lot of analysis, these misshifts appear to be more indicative of a design problem. The two largest sprockets on SRAM Eagle cassettes have a narrow-wide tooth profile. While narrow wide works extremely well on a chain ring, its use on a cassette is questionable. Narrow wide on a single chain ring setup works because the chain never leaves the ring.

Remember how narrow wide works : the chain ring has a series of alternating wide and narrowly cut teeth that integrate with corresponding narrow wide gaps in the male and female links of the chain (I’ll update this post soon with pictures). The chain can only fit around alternating links; and you can try this yourself,  shift the chain by 1 tooth on the chain ring and the chain won’t mesh at all instead sitting on top of the chain-ring. This obviously makes sense as the large tooth is too wide to fit in the narrow link. But as I said, this isn’t a problem on a single chain ring setup as the chain always remains in the same [synchronized] position.

This isn’t true with a cassette, the chain changes sprockets every single time a shift is made. And shifting isn’t a binary process; as you shift, the chain gets pushed to the side of the adjacent cog and  gets lifted by friction. Complicated ramps and tooth profiles help transition the chain as smoothly as possible onto the next gear but timing is still a fuzzy “let’s hope for the best” process, and expecting the chain to be synchronized on every shift is the only way SRAM Eagle can possibly work.

As I’ve experienced, this isn’t the case. I’ve seen several people experiencing similar problems, one of the mechanics says he’s even noticed it on his Santa Cruz but just lives with it. At a Yeti dealer we put one of the Eagle equipped bikes on the stand and were able to easily reproduce the problem, and I have recently come across two reports of broken teeth on the 50t cassette sprockets with no explanation for the damage. I suspect the violent shift of the chain dragging across the sprocket can put so much stress on the teeth that they can shear off under enough pressure :

 

SRAM Eagle shifting problem shears off the tooth from this cassette
Narrow wide tooth profile on SRAM Eagle cassette can have serious consequences on the cassette.
SRAM Eagle shifting problem destroyed another cassette
Another SRAM Eagle casualty from a nw tooth profile

Some people claim their Eagle is perfect, but I suspect these owners are accepting of the occasional clunk in their drive-train. And to be honest, a majority of the time SRAM Eagle does shift very well. Maybe I was spoiled with my previous setup : 2008 Shimano XT 3X, but after thousands of miles it still shifts flawlessly without a hiccup. I naturally expected my 10 year newer 1X “simpler” drive-train to perform at least as well but it doesn’t.

What’s more frustrating is how the 6 bike shops that I’ve gone to (all Trek and SRAM dealers) are incapable of diagnosing the problem and finding a solution. SRAM sent one dealer a new cassette and seemed aware of the problem. And after several more phone calls to SRAM they said that the chain on occasion can ride on TOP of the 42/50t sprockets – but they don’t know how to reproduce it. At least that’s what the bike mechanic who spoke with SRAM told me.

I’m trying not to jump to conclusions, but this appears to be a compromised design and a poor solution to prevent chain drop while backpedaling. If you have any insight into what is going on, please contact me directly or leave a message below.

High Mountain Trail Map

Update January 21st, 2018
– All map versions have been updated to version 1.0.4
– Improved map accuracy
– Cleaned up the Legend
– Added new trail 3B “Rabbit Hole” and 17A “Snake Bite”

Update October 16th, 2017
– All map versions have been updated to version 1.0.3
– Improved map accuracy
– Added new trail 12A – “H’s Way”, a better alternative back to Red from “Transfer”

Update August 6th, 2017
– All map versions have been updated to version 1.0.2
– Changed trail difficulty ratings
– Improved map accuracy
– Added missing uphill section to Ancients
– New trail added

Located in Northern New Jersey less than 10 minutes off state highway 287, High Mountain Park Preserve in Wayne township has become one of the premiere destinations for mountain biking in the state.

Rest assured, this is not your father’s High Mountain mountain bike destination. Yellow-Red-White blazed trails are a distant past (technically they’re still there) and you’ll never look at HM the same once you discover the endless miles of twisty single-track trails, the dozens of grueling climbs, and some seriously rad berms that will make even Steven Mancuso’s head spin. This is New School High Mountain.

Most of the trails are unmarked so it can be a little daunting for riders new to the area, but we’ve just made it easier for you with our High Mountain Trail Map :

If  you have a Garmin Edge 800/810/820/1000/1030

Download the High Mountain Garmin custom map (it also works as a Google Earth overlay).

For you Smartphone junkies

If you don’t have the Maprika App – get it NOW ! Then download the High Mountain Trail Map (you can search for our map by name within the app “High Mountain MTB” or get a list of all our maps by searching for “paulsmaps“.

Now… if you’re over 40 and didn’t understand a word you just read

You can download and print the PDF version instead 😉

Now shut up and ride and come back once you’re a believer.

High Mountain Aerial View

Check out all our other Cycling and Trail Maps 

 

Zipp 303 and Tufo/Jantex Tubular Rim Tape – Beware!

Since I’ve had good experience with tubular rim tape in the past (I used Tufo Extreme on aluminum rims when I rode l’Eroica last year and flatted twice – one so severe Stan’s sprayed everywhere – LOL – but using rim tape made replacing the tire a cinch) I decided to use the Tufo’s on my new Zipp 303’s…

until I went online and came across horror stories about carbon delamination! Several cyclists have trashed their rims while removing a taped tire as the carbon delaminates from the rim bed. Apparently, Tufo Extreme tape is just too sticky! Freaked out I took them off immediately (and carefully) and a flake of carbon (next to the spoke hole) came off with the tape!!!

@#*&$~!!!

When I chatted with a Zipp technician, he repeatedly stated that Zipp does not recommend ANY type of tubular tape (including Velox Jantex – I specifically asked) :

We do not recommend ANY tapes – they all tend to pull the carbon, add weight and increase your rolling resistance

My delamination was insignificant but the tape was only on for less than a week.

Garmin Edge 800 – Cracked Screen

I’m not going to give an in-depth review of the Garmin Edge 800 – DC Rainmaker already has it covered. Most reviewers conclude it’s a great device and I mostly agree, except for the very fragile screen that is prone to scratches and cracks.

Highlights

  • Touchscreen is very intuitive and a pleasure to use.
  • Touchscreen works suprisingly well; the virtual buttons are large and precise even with mittens at -20°C.
  • The unit is very reponsive (much more than my Nuvi 550).
  • Excellent bike mount, very secure, can’t imagine how the unit would ever fall off a bike.
  • Quick satellite acquisition and great reception even in the woods.
  • Custom maps created in Google Earth!

Downside

  • The touchscreen is extremely fragile and succeptible to chips and scratches. I’m not sure if this is an early production issue but the edges of the screen can easily be chipped with minimal pressure from a fingernail. I found this out while trying to remove a piece of debri stuck between the screen and outer bezel (strangely enough there is a 1/2mm gap between the two). When pressure is applied to the screen around the edges, it chips. The screen is also easily scratched and already has several hairline scratches from my gloves. I don’t know how the screens are manufactured but if they are cut to shape, the stress from cutting might be weakening the stuctural integrity of the plastic around the edges. I called Garmin (stellar customer support by the way) and they are replacing the unit at no charge. I asked them if the screen was more fragile than other models and the technician didn’t seem to think so. I hope Garmin is aware of the issue and has corrected it on current and future production units. If the screen itself cannot be strengthened, the outer bezel overlap should be increased to cover the edges of the screen by 1 mm to remove the gap. This would prevent dirt and debri from accumulating in the gap in the first place. If you must clean it, gently use the edge of a piece of paper to get inside the gap, then rinse or blow it clean (disclaimer: Garmin rates the water resistance as IPX7 – your mileage may vary). I would also recommend a protective film but again be careful with the amount of pressure when applying it.

If your unit has suffered from a chipped screen like mine, please leave a comment below with your unit’s serial number or simply send me an email at  . With your help and feedback we’ll have a good idea of what range of units were affected.

THANKS!

Recommendation

Although the Edge 800 is a fantastic device, I have a hard time recommending it until the screen issue is resolved. The Edge 800 is meant to be used outdoors on road and mountain bikes, but the screen is VERY fragile and can’t take the abuse even from the slight pressure of a fingernail. I’ve only used it for 10 days commuting to work. What will happen when I take it mountain biking and skiing?

Garmin Support

Garmin customer support so far has been second to none. My Nuvi 550 was destroyed on a cycling trip to Italy last fall when the Garmin scooter/bike bracket snapped; Garmin warrantied both the bracket and GPS no questions asked.

– Paul