Originally Posted by Gerry Hull

This is all technical info for someone who wants to make one. I don't want to waste time arguing a 'case' for it- so the below is relevant only if you're interested in how to do it. If you're more interested in the controversial aspect of things, don't waste your own time reading it.

Here are the little engineering problems that have to be solved if one requires a Dura Ace level of quietness, reliability and performance. Most issues arise out of the expanded range of chainlines. If the installation is on a TT bike (such as the poor Cervello P2 in the photo), your chainlines will be even worse. The shortened distance between crank and rear hub are responsible for that. The chainline in extreme gears are a strain even for a 2x10.

If you're doing this to a town bike or a hybrid with nice looong chainstays, hell, your chainlines with a 1x10 will be better than a 2x10 road/tt bike has. You got no worries and can ignore most everything that follows. You replace your stock square taper BB with a 108mm, buy a Tiagra 11-36 with compatible rear d, a fancy Paul's chainkeeper and GO.

For a road/TT bike with outboard crank bearings you've got to find a bottom bracket that includes 2-3 mm of spacers because that's about how far the big ring has to come in. And now your problems are just beginning. Did you have ankle/chainstay clearance problems before? You might have them now. Didn't think about that, did ya! I didn't.

For derailleurs, you have two options: buy an mtb rear d that is compatible with a road group (if you weren't a sram man before, you may have to be one now) or, swap/fabricate a new cage for your present rear der that is a) longer and b) has greater eccentricity of rotation about the pivot. I've done b) before and although it's lovely when you're done, I don't recommend it. You'll go through two or three derailleurs before you get it right, and that doesn't include the ones you'll buy just to rob their cages and return springs.

Suppose you get through that, you've got it pretty much set up and the chainlines in bottom and top gear really arent too bad, it shifts well. But you're fanatical about noise, or rather, hearing less of it. You also don't like it that when you backpedal in either the 11 or the 36, the chain jumps out of gear and that is no fun when the light is about to turn green. You've also got a bit of extra racket in those same cogs when you're rolling. Lastly, you've noticed that when your bike takes a weird bounce, the lower pulley has sounded like it's about to unchain itself. That would be very, very, very bad. Seen the photos of mangled Sram rear d's? That lower pulley is the cause, and you've just aggravated the problem with your oh-so-clever 1x10 set up. Lastly, you still drop the chain now and then - and one chain drop per season is one too many, for my money. Or, when you set the plates narrow enough to prevent that, you get chain rub when you're stomping on it. What is the point of getting rid of my fd if setting up a simple chainkeeper is so frustrating?

Here is where the real voodoo comes in, if you really want to stick to your objective of Dura Ace quietness, reliability, and performance. You've got to re-profile the teeth on your chain ring without taking too much away from the load bearing area. The 11 and 36 cogs will need a light chamfer in one particular spot to solve the backpedaling problem. The lower pulley wheel must be re-chamfered in order to eliminate its derailleur-exploding potential. And if you are perversely determined enough to figure out how to do that, there is still the g-d chainkeeper to deal with. In the end, that has ended up being the job that required an absolutely soul wearying amount of trial and error: design and positioning of the chainkeeper plates. Had it occurred to me earlier that a chain-keeper's job is entirely different from that of a derailleur, I would have gotten to the correct answer much quicker. But all the mistakes have yielded a more solid understanding of the configuration that works, as well as the principles behind it.

This week I'm taking the bike to the Cross Florida ride, and this should be the worst possible terrain for wide-range gearing. In fact it is. I suppose I could swap cassettes but I'm going to stick with the 11-36 just out of curiosity. The bike is weird enough apart from being a 1x10 and should probably be ridden as is so I can become familiar with it.

Is time for this thread to sink without a trace.
Have a beautiful day fellows.