For the past two weeks, I have been riding with an Efneo GTRO gearbox on my Univega. The GTRO is a 3 speed internal gearbox that replaces the front crankset and derailleur. This is a complete replacement, as you retain three distinct gear ratios – virtual 28/40/50t combinations. The crank was lent to us for testing and review. It was decided that I ride the most and would sufficiently test its abilities so I put it on my touring/commuting/mountain bike, replacing the triple crankset.
I was actually very impressed by the installation procedure. You are basically just replacing the BB then sliding a shifter onto your bars. The crankset comes out of the box ready to roll, fully assembled and totally adjusted, with what looks like a Microshift shifter branded Efneo. According to the company, the pull ratio matches Shimano’s MTB line (Deore) so you could use existing levers but I opted for the provided one because the cable pull and gear indicator numbers are reversed. The bottom bracket is dedicated to this system because it has a specific 30.5mm axle length and 46mm right cup size. Despite this, it is a high quality threaded bit made by Tange. Efneo offers it for 68mm & 100mm shells, and hopefully soon they will offer it in 73mm to fit touring mountain bikes, such as the Surly Ogre. All of this combines for a product that is not bound by proprietary, soon-to-become-obsolete pull ratios or – god forbid – bottom bracket standards. It will work on your average bicycle, which is a great thing. See here for further compatibility info.
TOURING IN MARIN
At this point, I probably have almost 500 miles on the crankset. These miles are composed of a couple weekend adventures, daily commuting, and those extra-long scenic commutes through the East Bay hills. I often ride loaded on this already-heavy bike, and the lowest gear was relied on for much of my riding. I found the 40t appropriate for riding on flats, and 50t perfect for ripping downhill or cruising in the fast lane. On the road, shifting is smooth and flawless, though you do have to let up on the power a little bit just like an IGH. I did take the GTRO on a lightly loaded two-day expedition through Marin County, where I found another advantage to internal front shifting when climbing Mt Tam back into civilization: you can keep your front in the smallest gear, while having full use of your cassette. This is a benefit on a climb with varying gradient, where the road may flatten out a bit but you know it will steepen up so you don’t want to shift completely. The same goes for downhill routes with small rollers. Essentially, cross chaining does not happen. The gearbox is also useful off-road, where you can shift without pedaling or use your whole cassette in any front combination. I had a few rides with the cranks off-road, and while I did break a bottle of beer in my pannier, the gearbox survived.
I see the GTRO shining in niche applications, like adapting your 8 speed town bike to hills without adding a derailleur, a low maintenance folding bike, or for the front drive of a cargo bike allowing you to shift while stopped. It seems durable enough for touring, generally uses standard parts, and can be combined with just about any rear drive – though be aware of max torque recommendations for SRAM and Shimano hubs.
It is a very well thought-out product, and is something that I can happily recommend for someone looking for a low-maintenance replacement to their front derailleur system, or looking to add range to their existing one-by town bike. I hope to continue riding the Efeno, and pass it along to some other mechanics in the shop to see how they use it in their own riding.
by Chris Corral
Blue Heron employee, UC Berkeley sociology student, adventure cyclist