After months of R&D and testing, we’re now offering Rene Herse cranks with a 40-tooth one-by chainring. One-by is a great idea: Get rid of the front shifts that always break your rhythm, and you end up with 11 or 12 consecutive gears. For most riders, that’s enough for all our riding – unless you’re a professional sprinter with an entire team to give you a leadout on the way to the finish line. One-by allows you to focus on the ride and think less about the bike.
One-by cranks have chainrings with alternating ‘thick-thin’ teeth that mesh perfectly with the inner and outer links of your chain. Otherwise, the chain will just fall off in the highest and lowest gears, where it runs at the most extreme angles. One-by chainrings also have taller tooth profiles that engage the chain earlier and more securely. (You don’t want the chain to climb over the teeth, as it would during a front shift.)
Key to good performance with a one-by drivetrain is a good chainline – you’re cross-chaining in the outer gears, and if your chain isn’t aligned with the middle cog, the cross-chaining will be even more extreme at one end of your gear range. The square-taper bottom brackets of Rene Herse cranks allow you to fine-tune the chainline by changing the spindle length of your BB. An 110 mm SKF BB will give you the same 45 mm chainline as modern road cranks. If you need extra room because your bike has very wide chainstays, go to a 113 mm spindle, or even wider, to a 116 mm.
Most other cranks these days have integrated spindles, and manufacturers make their one-by cranks so wide that they fit almost any bike. Apart from the wide Q factor, this also offsets the chainline to the outside. When you’re in the bigger cogs, the chain is noisy, shifting can be sluggish, and your drivetrain wears quickly. Fine-tuning your chainline allows you to optimize your drivetrain for your bike, rather than run a crank that’s designed for the widest chainstays out there.
We offer Rene Herse one-by cranks in two versions. The first one has dedicated arms for a single chainring. That’s the most elegant solution, and it’s also a few grams lighter. (Our one-by cranks weigh just 467 grams. Even after adding the bottom bracket, that’s still lighter than most other cranks.)
We also offer our one-by cranks with arms that can accommodate two (or even three) chainrings. In this case, our custom-machined chainring spacers take the place of the inner ring. That way, you have the option to convert your one-by to a double in the future. Simply install two new chainrings (and a front derailleur), and you’re ready to go. It’s nice to have the option if you find that you really want a closer-spaced rear cassette and need a few extra gears.
The cost of both versions is the same, simply choose the one you prefer. Like all our cranks, the one-bys are available in three lengths (165, 171, 177 mm). The arms are net-shape forged (with a dedicated forging die for each length). That makes them ultra-strong, and they pass the most stringent EN Racing Bike Standard for fatigue resistance. It’s good to know when you’re riding hard on bumpy terrain!
The spacers and chainring are available separately, too, so you can convert any Rene Herse crank to a one-by. It’s always our goal to make our parts backward- and forward-compatible – less waste and more money left over for great cycling adventures.
What about other chainring sizes? We started with a 40-tooth, because we feel it’s the most versatile size. Other chainrings will follow. Which tooth count would you like to see?
The one-by cranks are now in stock. Click here for more information about our crank program.