Tuesday, June 27, 2017

Simplified Drive Trains Complicated By Proposed New Developments

Getting rid of that front derailleur and adding wide range cassettes has its pitfalls.
Just the other day I mentioned in a post about how I wasn't necessarily a fan of the 1X drive train craze sweeping the mountain bike world of late. I do really like the idea for fat bikes, but there are issues when you try to make the chain do the physical gymnastics required of it to make a 1X drive train work. Especially if you want a wide range of gears.

Riders are finding this out now. New 2017 bikes with different lower end spec have been plagued by issues such as dropped chains, chains that derail when pedaled backward, and by noises and excessive wear. SRAM and Shimano have responded by making further tweaks to tooth profiles on chain rings and cassette cogs to allow chains to engage and release the teeth more efficiently, especially when coming off those big, 42T-50T rear cogs.

Basically, what has happened is that we've removed our front shifting issues and found them again on the back end.

Think about it- Big chain rings up front didn't want to release the chain or pick it up easily because there was so much more chain to teeth contact by virtue of the chain ring sizes. Now those sized cogs and bigger are found out back on many mountain bikes and the chain release issues have cropped up again.

This Shimano patent applied for design shows an axially movable chain line. Courtesy of Cycling Industry News.
Now Shimano and SRAM are applying for patents to address this issue. The ideas are different, but the results sought for are the same. Shimano suggests a bottom bracket spindle that telescopes in and out to straighten chain line, which would make the drive train more efficient and discourage chain drop. This solution does what we used to do with our triple chain rings and front derailleurs- straighten our chain lines out. Obviously it would make sense that Shimano would require the bottom bracket to telescope in a way somehow synchronized to the shifter. Di2 would make sense here.

It complicates the bottom bracket, for sure, and it puts a mechanism in a place where moisture could wreak havoc on the device. However; if anyone can engineer this to work right, I would place my bets on Shimano. Still, I am not convinced something this complex can survive the rigors of mountain biking. But we may or may not see............

SRAM's solution also alters the chain line but does it by a floating chain ring mount. Image courtesy of Cycling Industry News
 SRAM seems to have taken a different approach which seems to involve canting the chain ring in the direction of how the chain wants to flow back toward the cassette, depending upon the gear chosen. This option seems to not be tied directly to how the shifter operates and would appear to be simpler and effective. However, any time I've seen any chain ring allowed to move, (granted, it wasn't designed to move), it is not a good thing. This solution leaves me with a lot of questions and concerns. Also, the SRAM solution requires a special chain ring carrier, which would suggest that it only would work with removable spider designed cranks, perhaps. More places for creaks to happen, in my opinion, here with this design.

But what really strikes me here, and actually made me laugh out loud when I first saw this, was how all this getting rid of the front derailleur was going to simplify our drive trains. 

Apparently "simple" isn't working out as well as they hoped it would! But making it more complicated is the answer? I don't see this working out well...........


Phillip Cowan said...

Sounds like Shimano has adopted the German mechanical design philosophy. "Why make it simple when it can be complicated". Don't fear the triple, he is your friend.

Ari said...

There is nothing wrong with a front derailleur as long as the components are compatible and the rider does routine maintenance. I have noticed chains coming off cassettes when back pedaling. I called sram about this issue and support told me to "not back pedal"! Thanks geniuses, I thought to myself. The 12 speeders have even more of a drastic chainline. Good luck with that one.

Smithhammer said...

I've ridden the hell out of GX 1x11 on my trail bike (30t/11-42) and never dropped a chain. It's as crisp as it was over a year ago when I took it out of the box. No need for chain keepers, etc.

I put a Rival 1x drivetrain on my gravel bike a few months ago and it's been flawless.

I converted my fat bike to a 1x10 last year, and it's a mish-mash of parts - Surly cranks, Wolftooth ring and SRAM derailleur. Never had a chain drop with that drivetrain, either.

I just converted my wife's fat bike to 1x10, with a Surly crank, Wolftooth ring, SRAM derailleur and Sunrace wide range cassette - it works great.

I don't know about other people, but I had WAY more shifting issues and maintenance/adjusting needed when running multi-ring drivetrains. A 1x drivetrain, once it is set up properly, rarely requires anything after that.

Guitar Ted said...

@Smithhammer- The mere existence of these proposed changes by SRAM and Shimano suggest that many people are having issues with 1X. Also- no one is suggesting that the current offerings cannot possibly work for someone. As I have already said, I love it for my fat bike.

But, whenever you make an "upgrade" in one area, typically there are compromises made to get there. Your 1X systems, and everyone elses, have those compromises. Upsides? yes. But there are definitely compromises.

My biggest beef with 1X and wide range cassettes is based on chain line/chain release off the cassette and chain ring. That's probably the biggest compromise of 1X. The problems many others are seeing are usually also based upon those two issues as well.

Smithhammer said...

There are compromises with ALL drivetrains - 1x, 2x or 3x. It's just that people are so accustomed to the long-standing compromises of multi-ring drivetrains that they tend of overlook or downplay them. The compromises of a 1x drivetrain are compromises I'm happy to accept for most applications, as I find them to be of little consequence and significant benefit.

Yes, apparently, there are people having 'chain release' issues with their 1x drivetrains, though in practice I have no idea why. I've honestly never experienced that issue on any of the drivetrains mentioned above. My 1x systems are definitely simpler, cleaner and frankly, shift way better and more consistently. YMMV, of course.

Arky said...

I'm just sticking with 2x9: It works.