Recently I’ve been comparing and contrasting five drivetrains including a reversible single speed/fixed gear hub on an SE Lager; a touring triple crank with an 8-speed cassette on a Rivendell Sam Hillborne; a chain-driven Shimano Alfine 8-speed internal gear hub on a Civia Hyland; a belt-driven Shimano Alfine 8-speed internal gear hub on a Civia Bryant; and a SRAM i-Motion 9-speed internal gear hub on a Civia Loring. The following is not intended to be an exhaustive overview of the myriad drivetrains on the market; these are just my thoughts and impressions regarding these particular drivetrains.
Single Speed / Fixed Gear Drivetrain
I think the main attraction of single speed and fixed gear drivetrains is that they’re simple and bullet-proof. There’s an appeal to stripping a bike down to its bare essentials, eliminating the need for shifting and fussing with derailleur trim, etc. Eliminating a geared drivetrain is a significant weight savings as well. The obvious downside to single speed drivetrains is that you’re stuck with only one gain ratio, which may not work for people who live in hilly areas or for those who have physical limitations such as bad knees (which includes many of us over 40 who played sports or rode bikes their entire lives).
Touring Triple Drivetrain
For versatility it’s hard to beat a touring triple drivetrain. A triple provides the widest range of gears while still remaining relatively lightweight and simple to set-up and repair. With three chainrings up front and 7-10 sprockets is the rear, the potential for customization is nearly infinite within the range of the system. Disadvantages include the need for relatively high maintenance (due to exposure to the elements); a steep learning curve for beginners due to the complexity of overlapping ratios and multiple shifters, etc.; susceptibility to damage in public bike racks (again, due to exposure); and incompatibility with most chain guards.
Chain-driven Shimano Alfine 8-speed IGH
It’s no secret that I very much like the Alfine internal gear hub. A number of commuting bikes that I tested over the past year were spec’d with the Alfine including the Breezer Finesse, the Raleigh Alley Way, and the two Civias pictured here. At this point the Alfine IGH is a mature product with low failure rates and superb performance. When combined with the Rapid-Fire shifter (and assuming the cable is properly adjusted), shifts are clean, quick, and accurate. One major advantage of this and other high-quality internal gear hubs is that they can be shifted while stopped, coasting, or under power. Disadvantages include a limited gear range when compared to a touring triple; the need for either horizontal dropouts, an eccentric bottom bracket, or a chain tensioner to tension the chain; and added weight when compared to an SS or derailleur drivetrain.
Belt-driven Shimano Alfine 8-speed IGH
The only difference between a belt-driven and chain-driven Alfine IGH is the sprocket; the internal parts and shifting performance are identical. The Alfine IGH is known for being quiet and smooth, but the Gates Carbon Drive takes it to an entirely different (better) level. This combo is buttery smooth and nearly silent, almost like riding a well-oiled single speed drivetrain. If you’re already on-board regarding internal gear hubs, this is the next step that really completes the package. Disadvantages include the same as those mentioned above, as well as the need for a frame specifically designed to allow installation of a one-piece drive belt.
SRAM i-Motion 9-speed IGH
The i-Motion 9 is an internal gear hub from SRAM that competes directly with the Shimano Alfine 8. I’m really starting to enjoy this hub as I get to know it better. Besides the obvious advantage of having one extra gear, the i-Motion also covers a wider range (340% versus the Alfine’s 307%) and has more evenly spaced ratios than the Alfine. The smaller, more even steps between gears are a real advantage over the Alfine’s somewhat inconsistent spacing. The i-Motion is also easier to remove and re-install in the event of a roadside flat. Disadvantages include shifting performance that is not quite as smooth as the Alfine’s, and a limited selection of shifters, all of which are twist-type.
Let’s hear from you. What type of drivetrain are you currently running, and what would you choose if you were to replace your current drivetrain today?