Drive Train

I've decided to go with a 1x11 drive train using the Shimano XT 8000 series. I didn't want the trigger shifters that come with the drive sets, so I'm ordering stuff by the piece.

For the cassette, I wanted to have the biggest possible set of gears, which is the Shimano Deore XT CS-M8000 with an 11-42 range.  Best deal I found was $95 at Backcountry.  There were a couple place with slightly lower list prices, but with higher shipping costs.

The problem with going with something like an 11-42 cassette is that you can't be sure that a different manufacturer's derailleur will work.  So I got the Shimano XT RD-M8000 rear derailleur with a GS Cage (in black) for $78 from Jenson USA.

Shimano Deore XT M8000 1x11 crank $104 from BikeBling.  I've ordered the 165 mm crank - after reading some stuff at Bike Dynamics, I realized that I've been on stomping on too large of a crank for the past decade.  Note that unlike most cranksets that you find online, the M8000 isn't sold with a chainring - so it's only sort of a crankset.  Also, because of the asymmetry in the bolt holes (supposedly to optimize the loading) you MUST use a Shimano SM-CRM80 chainring!

To figure out what chainring I wanted, I went to Sheldon Brown's Gear Calculator and ran some numbers. Below is a table of the bike speed (mph) for 26 inch wheels at the rear cassette gears (1st column) for the 30/32/34 teeth chainring options when pedaling at 90 RPM.

	30	32	34
11	19	20.3	21.5
13	16.1	17.1	18.2
15	13.9	14.9	15.8
17	12.3	13.1	13.9
19	11	11.7	12.5
21	9.9	10.6	11.3
24	8.7	9.3	9.9
28	7.5	8	8.5
32	6.5	7	7.4
37	5.6	6	6.4
42	5	5.3	5.6

I've decided to go with the 34T, because this will keep me in the middle of the cassette when touring at 10 - 12 mph. The best deal I found on this chainring was with JensonUSA - the 34T chainring was $50.  Not cheap - but once you decide to go with a 1x11 system you lose a lot of flexibility in the components.  You can mix the SRAM 1x11 with the Shimano, but there is some noise on the interwebs about issues with chainlines.  Not sure that it really matters, but sticking with Shimano (or SRAM) seems reasonable.  They both have similar prices for what appears to be the equivalent XT quality.

For future reference, here's how the drive train speed varies with 34T chainring at different RPM

40 60 80 90 100 120 11 9.6 14.3 19.1 21.5 23.9 28.7 13 8.1 12.1 16.2 18.2 20.2 24.3 15 7 10.5 14 15.8 17.5 21 17 6.2 9.3 12.4 13.9 15.5 18.6 19 5.5 8.3 11.1 12.5 13.8 16.6 21 5 7.5 10 11.3 12.5 15 24 4.4 6.6 8.8 9.9 11 13.1 28 3.8 5.6 7.5 8.5 9.4 11.3 32 3.3 4.9 6.6 7.4 8.2 9.9 37 2.8 4.3 5.7 6.4 7.1 8.5 42 2.5 3.8 5 5.6 6.3 7.5

I completed the drive train with bar end shifters.  I didn't want the 11 speed trigger shifters from the Deore XT line, so  I ordered the 2 x 11 speed Shimano Dura-Ace SL-BSR1 bar end shifters - this was $93 from Jenson USA, so kind of pricey as it comes with both the 11 speed cassette shifter and a 2-speed front derailleur shifter. I figured I didn't need the latter (wrong!).  Ordering these Shimano bar end shifters was a major mistake.  After two days of mucking about (and thinking that I was just incompetent), I discovered that the 11 speed Dura-Ace (road) drive train has a derailleur that doesn't match the pull length for the shift points of the 11-42 on the Deore XT line.  You would think that indexed shift pull is an indexed shift pull, but noooooooooo.  Rather than order the correct trigger shifters, I went to work with a bench grinder and a Dremel hand grinder on the 2-speed front derailleur bar end shifter. I turned it into a simple friction shifter with sufficient travel to cover the full range of the 11-42 cassette.  It actually shifts quite smoothly, and to date (April 23, 2016). I'm not missing the indexing. But I could have saved a lot of money if I'd just bought a cheap bar-end friction shifter.