With the advent of wide geared cassettes for 9 and 10 speed mountain bikes (11-34 or 11-36 is very common) you may find the gears on your 27 or 30 speed bike are too close together. This results in too much time wasted shifting between gears and redundant gear ratios. Spend less time shifting (and tuning your front derailleur) and more time riding!
A 1X conversion consists of removing all the front shifting mechanisms and extraneous chainrings. One of the pleasant side effects of a 1X setup is the weight lost by removing two front chainrings, front derailleur, shifter, and cable. You’ll need to shorten your chain, add a chain retention device, and preferably switch to a short cage rear derailleur.
1X drivetrains put more emphasis into pedaling than shifting. If your granny gear gets too tough, stand up and crank on the pedals. You will be surprised at how steep a hill you can get up with a 34 or 36 tooth granny gear and a 30-36 tooth front chainring. You’ll also get up those hills much faster than your buddy who will be crawling along at walking speed spinning like crazy with his standard granny/granny setup.
The conversion process:
- Remove front shifter and front derailleur, toss them in the “I’ll really never need that but I save all my old bike parts” bin.
- Remove Small and Large chainrings from you crank. You may need to remove the crank to do so and you may need some small spacers or shorter bolts to re-install your middle ring.
- Install short cage rear derailleur (optional, but you really don’t need all the travel that the long cage derailleurs offer and a short cage keeps your chain tensioned better)
- Shorten chain
- Choose a chain retention device. Usually, the front derailleur does the job of keeping the chain from flying off the front chain rings, with it removed, we’ll need something else to take it’s place. Some people have great success sandwiching the chainring with two bash guards. Others prefer a clamp-on chain guide to keep the chain more secure. This is the only part of the conversion that adds any weight at all, so make sure you choose a chain retention system that optimizes your weight savings.
Switching to a 1X setup on your mountain bike will make your bike faster, lighter, simpler. It’s definitely a win-win situation. The only downside I can think of in my experience with 1X9 and 1×10 is that you can’t pedal any faster than 25-30mph (depending on the gearing you choose). But really, this is mountain biking! Any faster than that and you should just be coasting anyway. Have fun!