Myth BUSTED: "The Chain Drops On My Specialized E-Bike Because The Chainring Is Praxis WAVE"

[Stefan Mikes]

The Narrow Wide chainring teeth pattern was invented and patented as early as 1978 by a Wisconsin company Gehl. The idea was to create alternating narrow and wide tooth pattern to prevent chain dropping from the sprocket in agriculture machinery. Later, other tooth patterns such as SRAM X-SYNC or Praxis WAVE were invented. The special chainring tooth arrangement patterns became important since the introduction of 1x bicycle drivetrain by SRAM in 2012. The 1x drivetrain with a single chainring and no front derailleur has become the almost the only mid-drive e-bike drivetrain system used.

In the 1x drivetrain, especially with the growing number of gears and increasing cassette range (as huge as 10-52T cassettes), the chain line is very far from being straight. To prevent chain dropping incidents, the special pattern chainrings are used; additionally, premium derailleurs are equipped with a clutch that keeps the chain tensioned at all times.

Several Creo or Vado SL users have reported the chain dropping towards the e-bike frame, and attributed that to the Praxis WAVE tooth pattern of their chainring.

The background
I replaced the Shimano CS-HG500-10 cassette (10-speed, 11-42T) on my new Vado SL 4.0 in July 2021, after 1 month of riding the e-bike with the original drivetrain. My choice was the Deore XT CS-M771-10 cassette (10-speed, 11-36T) as it had it gears more evenly spaced. I have kept the original Praxis 44T chainring with chainguard. I was replacing chains as soon as each of them got stretched past the 0.5% mark. Doing so made the cassette still flawless after more than 10,000 km ridden!

Yes, I had a chain dropping towards the frame twice in quick succession. It turned out the derailleur/shifter indexing got misadjusted by one full position towards the largest sprocket, and the derailleur L limit screw was not set properly, either. After the necessary adjustment, my drivetrain has become perfect, silent, and totally reliable.

Moving away from the WAVE chainring
I have recently decided I needed a granny gear anyway (the Deore XT cassette has no granny gear!) so I reused the original 11-42T Deore one. Now, I wanted to use 116 link chains as these are easy to buy and not overly expensive. My calculation made me understand I needed a 42T chainring, so the derailleur would still work within its operational limit. Now, it has turned out buying a good 104 BCD, 4 hole, 42T chainring was almost impossible! Yes, no issue to buy a Garbaruk chainring, and Deckas chainrings could probably be bought (I have never tried a Deckas chainring before but I have a good experience with Garbaruk), To save me some money, I bought a French Stronglight chainring made of the 7075 superstrong aluminium alloy. Necessary to mention, the Stronglight has had a regular teeth pattern (and it was basically made for 2x drivetrains).

Note: The Praxis chainring showed the signs of being partly worn but it could probably be still used for the next several thousand of kilometres (a totally worn chainring has its teeth bent outside).

The Stronglight chainring installed on my Vado SL.

The little used 11-42T cassette reinstalled. I also used a brand new Shimano CN-HG95 chain (10-speed, 116L).

I paid a lot of attention to precisely adjust the derailleur/shifter and tested the setup on a 8 km ride. Then I set off for a 100 km gravel ride that involved a 9.2% grade climb and some descents.

The chain consistently dropping from the chainring in outer gears
While the drivetrain was working nicely in middle gears (2nd to 9th), the chain was consistently dropping from the chainring in these two exact situations:

• Towards the frame in the 1st gear
• Towards the crank in the top gear

The verdict is simple: You need a chainring that is specifically made for 1x drivetrains. Praxis with its WAVE patter has turned out to be a very good chainring. Please do not blame the Praxis WAVE chainring for your chain drops!

A word on Garbaruk chainrings
Yes, I have no other choice (except perhaps a Deckas) to replace the chainring than using a Garbaruk one. I have used two different Garbaruk chainrings on my e-bikes but there is a heads-up: Garbaruk chainrings use extremely long chainring teeth to prevent the chain dropping. It indeed works but the ring emits a grating noise when you are in the lowest cassette sprockets. Nothing wrong with that because you probably use the lowest gears rarely but be warned anyway. (At least the chain does not drop from a Garbaruk chainring).

Repeating myself: The WAVE or Narrow Wide pattern of your chainring is not the reason for your chain dropping! Blame anything else but the advanced chainring! Note: A Narrow Wide 1x chainring would work very well too (tested on my Vado 6.0).

 

[gpburdell]

The WAVE or Narrow Wide pattern of your chainring is not the reason for your chain dropping! Blame anything else but the advanced chainring!

You can say that but, my experience suggests otherwise...

• I'm well aware of the required chain orientation on the Praxis
• I verified derailleur limits and indexing were properly set as part of the once-over I do on a new bike
• Twice I experienced chain drop to the outside - both times shifting on bumpy asphalt.
• Replaced the Praxis 46T with a Wolftooth wide-narrow 46T
• No more chain drops since then

 

[Stefan Mikes]

Wolftooth wide-narrow 46T

A link please for one that you can actually purchase now.

You experience might be different from mine.

 

[gpburdell]

A link please for one that you can actually purchase now.

46T in stock and ready to ship:

110 BCD Gravel / CX / Road Chainrings

110 BCD 1x chainring sprocket gravel cyclocross cx road wide narrow wolf tooth drop stop

www.wolftoothcomponents.com

There have been times when it was out of stock - and they have an "email me when available" option in that event.

You experience might be different from mine.

Yes, I think it certainly has been. I get the idea of the Praxis - being stamped makes for less expense, but whether the design has issues or there's non-obvious defects causing chain drops, they are known to be associated with chain drops. Which go away when the person switches to a true wide-narrow chainring whether Wolftooth or other brand.

 

[mschwett]

…

Yes, I think it certainly has been. I get the idea of the Praxis - being stamped makes for less expense, but whether the design has issues or there's non-obvious defects causing chain drops, they are known to be associated with chain drops. Which go away when the person switches to a true wide-narrow chainring whether Wolftooth or other brand.

i had a few chain drops on the praxis ring. maybe 4 or 5 over a couple thousand miles. have not had any with the wolftooth ring. i conclude that they are both reasonable designs, but the precise profiles of the wolftooth dropstop ring worked better with the geometry and chain of my particular creo. i also switched to an SRAM cassette (to get a 10t) and corresponding SRAM chain, so perhaps that’s a factor too.

 

[Stefan Mikes]

46T in stock and ready to ship:

Didn't I say 104 BCD, 4 hole?

Didn't I say "from 40T"? A disappointing brand, isn't it.

Garbaruk has them all. See www.garbaruk.com

 

[pete H]

You guys have far more knowledge and experience than me but having been stranded 5 times in 12 months I'm happy to use the narrow wide ring as I've lost confidence in the Praxis.

 

[gpburdell]

View attachment 163756
Didn't I say 104 BCD, 4 hole?

You talked about Creo and Vado SL

My Creo takes a 110BCD five hole so that's what I provided, and the 12 speed SRAM models take 107BCD four hole model which is also available.

Perhaps the Vado SL is the odd man out that takes 104BCD in a size uncommon to mountain bikes and thus is not as readily available. As you noted though, Garabunk is a good option - particularly for for those on your side of the Atlantic.

 

[Stefan Mikes]

You talked about Creo and Vado SL

Perhaps the Vado SL is the odd man out that takes 104BCD in a size uncommon to mountain bikes and thus is not as readily available.

Not. All Vado or Como or Vado SL or Como SL derailleur e-bikes come with 104 BCD, 4 hole, 40-48T chainrings. I'd say many commuter or fitness e-bikes from big brands use that type of chainrings as all these e-bikes are hybrids derived from MTBs but need bigger chainrings for speed. Praxis makes e-bike non-MTB chainrings, hence the selection of the brand by big e-bike manufacturers. Deckas is another brand, and Garbaruk makes these chainrings, too.

110 BCD five hole is the road bike convention. 104 BCD 4-hole <= 38T is e-MTB.

P.S. I generalize. Trek is able to use even more weird chainrings such as 46T, 94 BCD four hole one on some Allant+ e-bikes. However, even Trek can use the 104 BCD chainring on the Allant+...

More and more funny

This is from Wolftooth. Has the brand recognised the presence of 1x cranksets, @gpburdell? (Yes, they have. For the 110 BCD 5-hole road chainrings. But not for 1x MTBs, it seems).

 

[eddief]

The Narrow Wide chainring teeth pattern was invented and patented as early as 1978 by a Wisconsin company Gehl. The idea was to create alternating narrow and wide tooth pattern to prevent chain dropping from the sprocket in agriculture machinery. Later, other tooth patterns such as SRAM X-SYNC or Praxis WAVE were invented. The special chainring tooth arrangement patterns became important since the introduction of 1x bicycle drivetrain by SRAM in 2012. The 1x drivetrain with a single chainring and no front derailleur has become the almost the only mid-drive e-bike drivetrain system used.

In the 1x drivetrain, especially with the growing number of gears and increasing cassette range (as huge as 10-52T cassettes), the chain line is very far from being straight. To prevent chain dropping incidents, the special pattern chainrings are used; additionally, premium derailleurs are equipped with a clutch that keeps the chain tensioned at all times.

Several Creo or Vado SL users have reported the chain dropping towards the e-bike frame, and attributed that to the Praxis WAVE tooth pattern of their chainring.

The background
I replaced the Shimano CS-HG500-10 cassette (10-speed, 11-42T) on my new Vado SL 4.0 in July 2021, after 1 month of riding the e-bike with the original drivetrain. My choice was the Deore XT CS-M771-10 cassette (10-speed, 11-36T) as it had it gears more evenly spaced. I have kept the original Praxis 44T chainring with chainguard. I was replacing chains as soon as each of them got stretched past the 0.5% mark. Doing so made the cassette still flawless after more than 10,000 km ridden!

Yes, I had a chain dropping towards the frame twice in quick succession. It turned out the derailleur/shifter indexing got misadjusted by one full position towards the largest sprocket, and the derailleur L limit screw was not set properly, either. After the necessary adjustment, my drivetrain has become perfect, silent, and totally reliable.

Moving away from the WAVE chainring
I have recently decided I needed a granny gear anyway (the Deore XT cassette has no granny gear!) so I reused the original 11-42T Deore one. Now, I wanted to use 116 link chains as these are easy to buy and not overly expensive. My calculation made me understand I needed a 42T chainring, so the derailleur would still work within its operational limit. Now, it has turned out buying a good 104 BCD, 4 hole, 42T chainring was almost impossible! Yes, no issue to buy a Garbaruk chainring, and Deckas chainrings could probably be bought (I have never tried a Deckas chainring before but I have a good experience with Garbaruk), To save me some money, I bought a French Stronglight chainring made of the 7075 superstrong aluminium alloy. Necessary to mention, the Stronglight has had a regular teeth pattern (and it was basically made for 2x drivetrains).

Note: The Praxis chainring showed the signs of being partly worn but it could probably be still used for the next several thousand of kilometres (a totally worn chainring has its teeth bent outside).

View attachment 163717
The Stronglight chainring installed on my Vado SL.

View attachment 163718
The little used 11-42T cassette reinstalled. I also used a brand new Shimano CN-HG95 chain (10-speed, 116L).

I paid a lot of attention to precisely adjust the derailleur/shifter and tested the setup on a 8 km ride. Then I set off for a 100 km gravel ride that involved a 9.2% grade climb and some descents.

The chain consistently dropping from the chainring in outer gears
While the drivetrain was working nicely in middle gears (2nd to 9th), the chain was consistently dropping from the chainring in these two exact situations:

• Towards the frame in the 1st gear
• Towards the crank in the top gear

The verdict is simple: You need a chainring that is specifically made for 1x drivetrains. Praxis with its WAVE patter has turned out to be a very good chainring. Please do not blame the Praxis WAVE chainring for your chain drops!

A word on Garbaruk chainrings
Yes, I have no other choice (except perhaps a Deckas) to replace the chainring than using a Garbaruk one. I have used two different Garbaruk chainrings on my e-bikes but there is a heads-up: Garbaruk chainrings use extremely long chainring teeth to prevent the chain dropping. It indeed works but the ring emits a grating noise when you are in the lowest cassette sprockets. Nothing wrong with that because you probably use the lowest gears rarely but be warned anyway. (At least the chain does not drop from a Garbaruk chainring).

Repeating myself: The WAVE or Narrow Wide pattern of your chainring is not the reason for your chain dropping! Blame anything else but the advanced chainring! Note: A Narrow Wide 1x chainring would work very well too (tested on my Vado 6.0).

I dumped the Praxis for two reasons. One was that it was falling off occasionally for seemingly no reason at all. The other was the stupid alignment graphic being on the inside of the chainring. Good luck getting the chain aligned after it falls off by trying to even "see" the darn graphic as you reinstall the chain. My Woolftooth replacement has been problem free.

 

[Stefan Mikes]

My Woolftooth replacement has been problem free.

Where is the chain alignment graphic on the Wolftooth ring?

 

[pete H]

I dumped the Praxis for two reasons. One was that it was falling off occasionally for seemingly no reason at all. The other was the stupid alignment graphic being on the inside of the chainring. Good luck getting the chain aligned after it falls off by trying to even "see" the darn graphic as you reinstall the chain. My Woolftooth replacement has been problem free.

Definitely agree with you there! Did manage it on the bike stand at home eventually but at the side of the road in the middle of nowhere practically impossible!

 

[Stefan Mikes]

Definitely agree with you there! Did manage it on the bike stand at home eventually but at the side of the road in the middle of nowhere practically impossible!

Guys,
You need no diagram as long as you have watched your chainring and the chain from the top at least once...

 

[gpburdell]

Where is the chain alignment graphic on the Wolftooth ring?

It's not needed when you physically can't put the chain on incorrectly - the wide teeth won't fit into the narrower part of the chain.

This is the case for any true wide-narrow chainring whether Wolftoooth or Garbaruk or other brand.

Guys,
You need no diagram as long as you have watched your chainring and the chain from the top at least once...

Correct.

 

[pete H]

Yes I understand that but I think we were talking about the Praxis wave chainring with the location sign on the inside of the ring.

 

[gpburdell]

Yes I understand that but I think we were talking about the Praxis wave chainring with the location sign on the inside of the ring.

Not sure who you're responding to.

Yes, the Praxis has the graphic on the inside of the ring. It's also unnecessary if you observe that the teeth sit to the inside edge of the wide-gaps of the chain when properly mounted, which you can see looking at it from the top.

 

[pete H]

I did not know that! It's written nowhere. I was told by LBS that the connecting link had to sit exactly in the middle of that graphic. You see why i was having difficulty now? So good information to anyone who thinks the same.

 

[gpburdell]

The connecting link? As in the quicklink holding the chain together? Good grief.

Any of the wide links can sit in the middle.

and yes, it's not written anywhere official that you can see proper orientation from above, it's just something folks noticed.

 

[eddief]

If Woolftooth can do it without worrying about aligning the chain to the graphic or hovering over the chainring to make sure the chain it aligned then I choose Wolftooth. I was on a bike tour in the middle of bumfuk and the chain came off. I'd prefer not to have to use a magnifying glass at the side of the road to ensure I get the links lined up correctly.

 

[GuruUno]

I continue to have the same issue with the chain coming off. I put about 6,600 miles on the 2022 Vado 5.0 in 16 months, replaced the chain every 1500-2000 miles, new cassette at the same time and it eventually happens, many, many times. Discussed it with the local bike shop Guru, and he experienced same issue with his Vado when he had one. His opinion makes sense. He, like I, do a lot of upshiting and downshifting and when coming to a stop and downshifting and upon eventually stopping, it's like the internals of the motor are still slightly spinning and that ever so slowly puts the chainring out of sync with the chain. You should notice that it is usually when starting from a dead stop, and had just downshifted prior to stopping. Upon stating off again, the chain is popped off of the chainring. Seems like a common problem with a lot of solutions. I may consider the Garbaruk chainring next time. I always use the KMC e11 chain, and I always wax the chains (hot wax dip).