If you saw my '7 Little Bikes That Make Me Want to be a Kid Again
' piece, you already know that youngsters can get their hands on way neater stuff than previous generations ever could have. There are more and more solid options when it comes to pint-sized mountain bikes, too, with brands like Spawn, Rocky Mountain, and others putting out some proper machines made for some proper riding. Some even have decent suspension forks, shocks, and disc brakes, but our little buddies are often left using a less than ideal drivetrain. Either they get an expensive custom setup, a hack job of parts intended for adults, or a super budget crankset with (gasp) multiple chainrings. At this point I can barely remember how to use a front derailleur, so I don't know how anyone could expect Fortnite-addled tweens to avoid cross-chaining.
A decent single ring drivetrain simply makes the riding experience better, especially if you're just starting out in this game, but a complete kid's drivetrain just isn't a thing. Wasn't a thing.
SunRace's new M9 Juvenile series is a complete 1 x 9 groupset designed for kids and that can be had with an 11-50, 11-46, or 11-40 cassette. Cranks will come in 140mm or 152mm lengths, with shorter options possibly in the cards down the road, and the 287-gram rear derailleur even has a clutch to keep the chain where it's supposed to be.
Not surprisingly, SunRace has original equipment in mind with the M9 Juvenile group, but they haven't ruled out aftermarket sales, either. No word on pricing, but we hope that this will help get decent 1x drivetrains onto more affordable kids' bikes.
And now here's something for grown ups. The new MZ group sits atop SunRace's drivetrain hierarchy, and you'll find touches like a carbon fiber cage, an adjustable clutch, and aluminum pulley wheels (ack, sounds noisy) with sealed bearings on the highest-end rear derailleur.
You can skip the alloy pulley wheels to save a bit of money and weight, with the standard model coming in at 267-grams and the fancy pants one weighing a measly 5-grams more.
There are two versions - one compatible with SRAM shifters and the other for Shimano - and SunRace says that they'll work with 10, 11, and 12-speed cassettes. They look pretty nice, too, especially with the ti-nitride gold chain. Want less bling? There are black and silver options as well.
The shifters appear to be less polished, but there are four different versions to choose from depending on how you want it to mount (clamp or a Shimano-compatible I-Spec setup) and whether you want a giant gear display to look at or not. The right answer is 'No,' of course. There are five different 12-speed cassettes to pick from as well, with aluminum used for the top four cogs on the nicer models.
Gearing range runs from either 10-50 or 11-50 teeth, and weights start at 462-grams before topping out at chunky 702-grams for the all-steel-cog version.
Nearly lost in the slew of new bits is how SunRace is attaching their two 10-50 spread cassettes to SRAM XD-style freehubs, especially since the cassettes sport a Shimano-style splined interface. The answer is a freehub adapter of sorts looks like a stubby, tapered sleeve with Shimano-compatible splines along its length. That little guy slides over the XD body, and then SunRace's cassette slides onto that before a threaded lockring clamps it all down.
You're probably not alone if you're sitting there asking yourself why someone wouldn't just run a relatively inexpensive SRAM GX cassette, but the answer comes down to saving money. SunRace says that if you use their freehub adapter and cassette, you'll end up keeping around €50 retail in your pocket compared to a GX setup. Whether or not that's worth the added complication of a freehub adapter is yet to be seen.