3 days ago
Ride Review: Honda Grom 125 Minimoto With A Belt Drive Upgrade
The Honda Grom is the little motorbike that can... get you anywhere in a city and quickly. It's a ... More real-deal motorcycle with a clutch and gears, but fun-sized and affordable.
In 2014, Honda debuted an oddly named, somewhat unusual but instantly popular new motorcycle: a half-sized street bike called the Honda Grom 125. What's a 'grom?' It's slang for a young or newbie action sports participant, which is probably a good description for many Honda Grom owners. Back in the day, we called Honda's half-pint motorcycles 'minibikes,' but those were 50cc buzzers more at home in the dirt than on the street, even though they were street legal. The Grom somehow has adult-sized ergonomics, and Honda sells these affordable urban fun machines - now called 'minimotos' - by the shipload for $3,599 each. To be clear, Groms are not scooters or mopeds and require clutch and shifter skills to operate a five-speed gearbox. They are actual motorcycles and require an endorsement on the rider's license in most U.S. states.
The Grom has some style points with its gold forks, angular bodywork and exposed mechanicals.
Too small and slow to ride on freeways but absolutely aces in town, the Grom (and a growing roster of other 125cc retro-terrific siblings from Honda and others) have become a gateway to motorcycle fun for thousands of first-time riders and returning veterans alike. Urban Grom riding groups are popular, and customizing Groms is an industry unto itself, as evidenced by the numerous custom Groms on display at the most recent edition of the popular One Motorcycle Show in Portland.
While enjoying the One Moto Show in my hometown, I connected with some folks from Gates Corporation, specialists in carbon belt drives, and rode a Grom customized with a Gates belt drive conversion kit, which is still in development but nearing production. For comparison, I rode both a stock chain-driven Grom and the belt drive conversion bike seen in these photos.
This Grom is converted to belt drive from chain, but it's hard to spot the change and that's ... More intended.
All motorcycles use one of three different final drive systems to transfer engine power to the rear wheel: chains, shafts, or belts. Chain drive systems remain the most common because of their reliability and high strength. However, chains require near-constant maintenance, including regular lubrication and adjustments to tension and sag. In contrast, shaft drive systems need less maintenance but present issues with drivetrain behavior, which typically restricts them to cruisers and adventure machines, such as BMW's popular GS models.
Electric motorcycle manufacturer Zero exclusively uses Gates belts, while Harley-Davidson transitioned from chain drive to Gates belt drives in the mid-1980s. BMW utilizes shaft drive on nearly every bike it produces. Italian brands like Ducati and Aprilia, along with all Japanese manufacturers, primarily employ chain drives on most bikes, especially high-performance models; some cruiser models feature shaft drive. Currently, none use belt drive on any models. More recently, many e-bike makers are offering models with belt drive to reduce maintenance needs, weight, and simplify drive systems.
A Gates carbon belt is a complex product with multiple layers of materials designed for long life ... More and quiet operation.
Ironically, early 20th-century motorcycles all used belt drive systems—except that back then, the belts were made of leather and tended to break, which led to the eventual widespread use of chain and shaft final drives. Modern belt drive systems, such as those from Gates, are made of a complex mixture of materials (above) that provide a service life far longer than a chain, operate in near silence, and require little to no maintenance, apart from periodic tension adjustments.
A close-up view of the Grom's belt drive. New Gates belts are skinnier and work with smaller ... More sprockets.
With a motorcycle like the Grom, which Honda designed for a life of minimal maintenance and heavy use, it seems a belt drive system would be an excellent fit, both literally (above) and figuratively. With a 50,000-mile service life and infrequent adjustment needs, you'd think Honda would be eager to eliminate 'chain maintenance' from the Grom's already short upkeep list and implement a belt drive. But so far, no luck. The upcoming Gates refit kit should bring those benefits to bear for Grom owners.
On city streets, the Grom has no problem keeping up with traffic, but you do feel... a bit small and ... More exposed. Best to ride in packs.
That all said, is there a difference in the riding experience between a chain and the Gates belt conversion on a Honda Grom? We took to the streets of Portland's hilly West Side to find out. Full disclosure: This was my first time at the controls of a Grom. I'm not sure how Honda made a motorcycle that looks like it could fit in the back of most hatchbacks actually fit a large human like me, but it does. The fuel-injected 125cc air-cooled motor is peppy and fun, and the Grom even includes a shift light for those low-speed stoplight races. Flat out in 5th gear, the Grom can just top 50 mph. Freeways are a no-no for the Grom and its 125cc friends, but on city streets, the light weight, small wheels and zippy motor are highly entertaining, and the Grom is easy to ride. It can change direction quickly, you put both feet flat on the ground at stops, clutch engagement is highly forgiving, and the Grom feels well-made and solid underway. I can see the appeal!
I rode the chain-driven Grom first, and the experience was pretty much as expected, which is to say, normal regarding drivetrain feel and action. Switching to the Grom with the belt drive kit, the riding experience is… pretty much the same as with a chain, which is not a demerit. However, there are some small differences. Since the belt drive has more elasticity than a chain, transitions on and off the throttle have a bit more smoothness as the belt absorbs some of the transitional energy. Other than that, the experience is identical to a chain, which is the point, to a large degree.
Clean, light and quiet, the Gates belt drive conversion kit should be a popular item for Grom ... More customizers.
The real advantage of the Gates belt drive conversion over the stock chain drive lies in all the benefits mentioned earlier: lighter weight, a much longer service life, and minimal maintenance aside from a periodic tension adjustment (it should be checked annually). Forget about the need to remember to oil a chain, constantly check for chain sag, look for wear, and replace sprockets when changing the chain. Weight, time, and money are saved by opting for a belt (which includes a belt-specific sprocket replacement kit that retains stock gearing ratios).
A Gates representative told me that new advances in belt construction allow for tighter rotation around sprockets, allowing for smaller, thinner, more 'normal' looking belt drive systems that previously required large, wide sprockets for proper tension and operation. Without those advancements, an install on a small bike like the Grom might not be possible.
As noted, the Gates Grom belt drive conversion kit (and possibly additional kits for other motorcycles) is still being finalized for production specifications and pricing. If Honda were smart, they'd either offer it as a kit, a factory option, or simply make the Gates belt drive standard equipment on their popular minomotos. Because simpler is always better.
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