Harley-Davidsons are special. Aside from their unique "potato-potato" exhaust note, they stand apart from most motorcycles mainly due to their single-pin crankshaft design and their belt final drives. Some have earned a reputation for being the coolest motorcycles around while also being the most difficult motorcycles to handle. Harley-Davidson used chain final drives all the way up to the 1980s, with the belt final drive first debuting on the FXR Super Glide II. Considered as low-maintenance and quieter alternatives to chain drives, belt drives soon became mainstream in Harley-Davidson motorcycles, even on newer Harleys like the Nightster that feels so right, it must be wrong.
That said, some Harley riders still prefer chain drives. Those have been around since the inception of motorcycles and have largely remained unchanged since then. That's because chain drives are durable and known to last for a long time. This leads to a lot of questions. Why does Harley-Davidson insist on belt drives while some Harley riders insist on chains? And if you were to swap your Harley's belt drive for a chain drive, what do you need to know? Before that, let's brush up on the types of drives and whether belt or chain is better.
You need a medium to get the power from your engine to the driven wheels for your vehicle to move. For four-wheelers, it is mostly done via a drive shaft or propeller shaft. Two-wheelers — motorcycles in particular — mostly rely on chain drives to get the job done, but some use belt drives instead.
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A chain drive consists of a metal chain that links a sprocket on the gearbox output shaft to a sprocket on the rear wheel. Belt drives operate on the same principle, but instead of chains and sprockets, you have geared pulleys and a belt with teeth on the inner side. These teeth mesh with the teeth on the pulleys, providing the driving power.
Harley-Davidson made the switch from chain to belt drive as the latter was smoother and quieter. Belt drives use Kevlar or carbon-reinforced belts with precision-cut grooves, meshing perfectly with the gears in the pulleys to offer a smooth operation. They are also relatively low-maintenance and cleaner since they do not need greasy and messy lubrication, unlike chain drives. If properly maintained, a belt drive can last up to 100,000 miles.
However, it is easy to damage a belt drive. If small stones or rocks get in between the belt and pulley, they can easily damage the former's teeth. They can also get ripped apart under shock loads, such as when you pull a wheelie or suddenly accelerate. While the belt has good tensile strength, a sizable shock load can easily exceed its power.
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Chain drives are all about sheer strength. They can handle brutal shock loads without coming apart, which is one of the reasons why they're so durable. They are also more efficient than belt drives, offering 1-4% transmission losses compared to a belt drive's 9-15%. Chain drives also take up less space than belt drives and offer a cheaper and wider option of altering final drive ratios by changing the sprocket sizes. These are also more resistant to breakage due to foreign objects being stuck between the chain and sprocket. However, while chain drives are incredibly strong, they do need regular cleaning and lubrication, as well as tension checks. Also, an open chain set will fling lube over your rear wheel and trousers.
Some Harley riders replace their motorcycle's belt drive with a chain for a few important reasons. For one, a chain drive is more durable and less susceptible to damage, so it makes sense for someone who puts long miles on their motorcycle in less-than-ideal road conditions. Also, on the road, it is easier to fix a broken chain than a belt, which cannot be repaired. Those who maintain their own bikes prefer chain drives, as replacing a belt requires extensive disassembly, which sometimes includes dropping the swingarm. Harley riders modifying their bikes for sports such as drag or dirt racing might choose to swap to the more-durable chain drive. Custom bike builders might also prefer chain drives as they offer a minimalistic, cleaner look compared to the large and ungainly-looking belt-and-pulley system.
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If you ride a stock Harley-Davidson, leave your bike's maintenance to the professionals. If you like your motorcycle spotless and your rides mainly consist of pristine highways, stick to the belt drive. These perform flawlessly in the environment they are intended for. A belt drive offers a smooth and quiet operation, is low maintenance, and can last long if looked after properly.
However, if you have modified your Harley to produce high horsepower, it is a good idea to switch over to a chain drive. Chances are, the stock belt drive can't handle the additional performance. Also, if you ride aggressively, love to pull wheelies, or execute stunts on your Harley, this is one modification you should look at. Another reason to move over to a chain drive is if you want to ride more in the dirt. Harley's own adventure bike, the Pan America 1250, uses a chain drive and does everything you doubted it could off-road.
While switching over to a chain drive, there are some factors to consider. You need to purchase the right conversion kit; it's not a straightforward fit, as belt drive Harleys are not designed for a chain drive setup. Go with the conversion kit for your specific motorcycle model and manufacturing year. You need to ensure that your transmission and rear wheel sprockets are aligned straight; most conversion kits include the offset sprockets or spacers. You'll also need to check for chain clearance, as the chain could rub against the passenger footpeg mounts or muffler mounts. You might even have to modify or remove the belt guard for a clean fit.
