How to: Install a Race Face narrow-wide chainring
I'll be the first to admit that new gear motivates me to go out and ride. It's a classic case of guilting myself into fitness, but whatever works, right?
The latest mod to my 2003 Giant AC-2 (it's 13 years old, no typo) is a 1x9 drivetrain conversion. Basically, it means removing the triple chainring setup and all associated shifting hardware and replacing it with a single chainring. The motivation for this mod is twofold. First, it simplifies the ride. By choosing the proper chainring and cassette size, you can retain a completely useable subset of the stock gear combinations while completely removing the front shifting mechanism. Secondly, it significantly* reduces the overall weight of the bike .
* relatively speaking
Here's how to do it
Remove the drive side pedal. You'll need a pedal wrench, or a slim 15mm open-end wrench. Remember, drive side pedals are standard thread, non drive side pedals are reverse thread (lefty-tighty..).
Remove the drive side crank arm. The one shown here is an splined ISIS drive type and was removed with an appropriate crank puller.
Remove the stock chainrings. If your setup has a triple chainring combination in the front, the middle and big ring are attached to the crank spider with a common set of bolts. The small ring is attached with its own set. A 5mm allen wrench is the standard tool for this job.
Note, you may need to hold the chainring nuts in place with a special tool, or a flat head usually works. Or in my case, I didn't need anything; the nuts stayed in place as I loosened the bolts.
Attach new chainring to stock crank spider. The key here is to note the BCD (bolt circle diameter) and make sure your crank spider matches the new chainring. This set up is a standard 4-bolt 104mm BCD.
Note: The configuration of the Race Face chainring depends on the size you get. I got a 30T ring, and because of it's small diameter, it has threaded and offset bolt holes, whereas any larger size has standard non-threaded chainring holes. Also, using the chart provided by Race Face, I determined that my setup required 8.5mm chainring bolts with no shims required. I was able to use the inner (small) chainring bolts for this purpose as they were exactly 8.5mm.
Close-ups of the new chainring:
Note the threaded bolt holes on the 30T version.
The offset on the chainring allows for chain clearance without the use of any spacers (very nice). The 'narrow-wide' configuration refers to the tooth pattern: narrow-wide-narrow-wide... This meshes with the chain (which has narrow and wide gaps between the plate due to the nature of the chain construction) extremely well and minimizes dropped chains, so that a chain guide and a clutched derailluer are unnecessary.
Install the rest of the drivetrain. Since this bike is 13 years old and the drivetrain has never been touched (stock chain even), I decided to replace the whole thing. I went with a wide range 9-speed cassette (12-36), and a new HG chain with SRAM powerlink.
Plenty of chain clearance due to the offset on the chainring.
Simplified handlebars - only one shifter.
Bask in the glory.
For under $100 (chainring, cassette, chain, powerlink), I was able to drop nearly a pound from the bike. The weight of the 3 rings, the shifter, and front derailluer comes in at 1.06lb. However, the weight of the new chainring (37g, or 0.08lb) and a slightly larger cassette yields a net weight reduction of about 0.95 lb. Granted, the bike is a tank at over 35 lbs, but this type of weight reduction is usually reserved for high-end carbon upgrades running several hundreds of dollars or more. The weight reduction, combined with a new feel to the bike, make this upgrade well worth it in my opinion.
A note on gear combinations:
Before I did this upgrade, I was a bit concerned about loosing the low end of the gear ratios. Although I never used the absolute granniest of granny combinations, I wanted to know what the new minimum gear ratio would be.
The stock setup had a 22T small ring and a 34T large cog (pretty standard for a 9-speed, triple), offering a minimum gear ratio (GR) of 0.65. The smallest GR I ever really needed (on a good day) was granny gear with the 28T (3rd biggest cog) (GR 0.79).
With the new setup, my smallest GR is 30 / 36 = 0.83, which is a bit of an increase, but hasn't proven to be problematic yet. Optimistically speaking, it's a brute force way of increasing my strength.
On the upper end, the old maximum GR was 44 / 11 = 4.0. With the new setup, the maximum GR is 30/12 = 2.5. This is a big reduction on the high end, but the general consensus is "who cares?" In other words, how often are you in the big ring flying downhill wishing you had more gears? Probably never.