In the world of cycling tech, there always seem to be new things that offer the potential to either revolutionize the industry or become a bizarre relic of the cycling tech past.
The latest such phenomenon? Belt driven bikes.
Belt-drive bikes essentially replace the chain on a bike with a continuous “belt” without links. This technology has been snatched straight from the automotive industry, with 10,000 horsepower F1 racing cars using belt-driven engines.
However, in the context of cycling, this comes with a range of competing benefits and drawbacks, which make belt drive bikes extremely well-suited to some riders and a potentially Watt-sapping gimmick for others.
But are belt-driven bikes more efficient? Is it easy to switch to a belt-drive bike? And could a belt driven bike be suited to you?
In this article, we’ll discuss how belt drive bikes actually work, and the benefits and drawbacks of running a belt-driven drivetrain over a chain-driven one.
We’ll be covering:
- What Are Belt Drive Bikes?
- How Do Belt-Driven Bikes Work?
- 3 Key Benefits Of Belt Drive Bikes
- 5 Drawbacks Of Belt Drive Bicycles
- Should You Switch To A Belt-Driven Bicycle?
- Final Thoughts: Gimmick Or Game Changer?
Let’s dive in!
What are Belt Drive Bikes?
A belt driven bicycle is basically exactly what it says on the tin.
The “belt” is a continuous piece of polymer that is reinforced with extremely strong carbon fiber chords. It consists of a series of uniform “bumps” that slot into the teeth of the chainrings and rear sprockets.
How Do Belt Driven Bikes Work?
They work in a fairly similar way to a chain-driven bike.
The belt’s bumps slot into the teeth of the front and rear sprockets. Upon rotation of the pedals, power is transferred from the chainring (front gear) to the rear sprocket via the belt, forcing the wheel to rotate.
Although this may sound extremely familiar to chain users, there are some major differences between a belt drive bike and a chain-drive bike.
For this reason, you’re most likely to spot a belt drive in the wild on a single-speed bike. Having said that, it can be used on a multi-speed bike by installing retro hub-driven gears or a gearbox.
3 Key benefits of a belt drive bike
So, given it’s such a big shift (if you’ll pardon the pun) from a chain-driven bike, why would anyone want to do it?
Well, belt-drive bikes do have a number of clear advantages when compared with traditional chain-driven ones.
#1: Low Maintenance drivetrains
The most obvious of these is the extremely low-maintenance drivetrains.
The lack of need for lubrication means that a belt requires significantly less maintenance than a chain. Chains get extremely dirty (particularly when used with wet lube) and necessitate more regular cleaning and re-application of lube.
Belts, on the other hand, stay remarkably clean, without anything to allow dirt to adhere to it. This is, of course, an advantage in itself. However, it also takes us to our next point.
#2: Weather Resistant
Belts are far more resistant to adverse weather conditions.
The meaning here is two-fold: firstly, in terms of wear. A belt is not made of reactive material. Polymers and carbon fiber do not react with oxygen or water and degrade, as opposed to the regular steel chains, which massively degrade with excessive exposure to either.
Secondly, in terms of efficiency. In adverse weather conditions, the dirt that accumulates on a chain clogs up the mechanism by getting in between the pins and the rollers and introducing an additional source of friction, slowing you down.
However, belts do not have such problems because they don’t attract nearly as much dirt, and also, since they are a continuous piece of material, they don’t have a hinging mechanism to get clogged up.
Another important point is that, due to the reduced wear from external conditions and the continuous nature of a belt, it will last far, far longer than a chain. Many belts will last 40,000+ km before needing replacing. This is at least 3-4 times longer than any chain.
This is largely due to the simplicity of a belt. There aren’t all these moving parts with the potential to degrade or wear in the same way that there is with a chain.
It’s also due to the material. Carbon fiber is extremely strong and not nearly as ductile as steel, which eventually will stretch and become less efficient.
5 drawbacks of belt drive bicycles
So, clearly, there are many benefits to using a belt over a chain – but then, why are they not the default choice for bicycle manufacturers?
Well, there are also a significant number of disadvantages to belt-drive bikes.
#1: Derailleur Incompatibility
The first, and definitely the biggest, is the incompatibility with derailleur gears. This is a complete deal-breaker for many riders.
Although a belt drivetrain can be paired with hub gears or a gearbox in order to retain multi-speed capability, these options are far less efficient than the streamlined derailleur gears we’re used to.
So, for racers, this is a complete deal-breaker. If you’re using your gears a lot, those extra Watts you’ll save from the gear-changing efficiency outweigh any maintenance gains.
#2: Extra Weight
Using a gearbox will also add at least a kilogram to your setup, another deal breaker for racers, particularly climbers.
It’s not just the gear-changing mechanisms that are more efficient, either.
#3: Efficiency Loss
It should be noted, however, that the difference in efficiency depends on the load put on the pedals by the rider- though, at a typical wattage output for an amateur, the difference is a hefty 35%.
However, while this sounds like a lot, the efficiency loss of the belt drive is still only around 4 Watts, just 1 Watt more than from a chain drive – a difference that is more or less undetectable to most riders.
#4: Lack of Repairability
Another drawback of using a belt is its repairability.
Unfortunately, a snapped belt is a bin job. On the other hand, a snapped chain in otherwise decent condition can be easily repaired with a new link.
#5: Special Equipment
Belts also require the use of a special frame.
This is because the rear triangle must be split in order to allow for the one-piece belt to be fitted to the bike. So, replacing a chain for a belt is not possible – you need a new bike.
Additionally, belts aren’t usually sold in local bike shops, and bike mechanics may have less experience with belt-driven bicycles if they encounter issues with your belt.
Should You Switch To A Belt-Driven Bicycle?
There are lots of things to consider before re-mortgaging your house and running out to buy a belt-drive bike.
The first, and most important consideration, is what type of rider you are.
If you’re a hill-climb racer or a speed demon on a road bike, then a belt just isn’t for you. The less efficient drivetrain (when new) and the less efficient shifting just won’t be worth the improvements in maintenance and lifespan.
Mountain and gravel biking are much less clear, but likely remain better with a chain. Both of these disciplines would vastly benefit from the cleaner and lower-maintenance drivetrain, but would both hugely suffer from the decreased shifting efficiency.
Off-road cycling requires constant gear-shifting as you traverse the varying terrains and gradients, to attempt to keep your cadence roughly constant. So, the decreased efficiency of shifting, and the poor shifting under load is likely to be a huge blow to any off-roaders.
The group of cyclists who may benefit from a belt-driven bike are urban cyclists. This includes those with city bikes, single-speed bikes, fixies, hybrids, and commuter bikes.
In this case, the bike simply doesn’t really need gears, and most of the disadvantages of a belt drive are negated. This group of riders will also hugely benefit from the decreased maintenance, saving a huge amount of time in the long run.
If you’re using a single-speed belt-driven bike, you’ll spend next to no time maintaining the drivetrain. If you’re just using it to zoom from A to B or to get to work, then the lack of gear ratio options doesn’t really come at too much of a cost.
The next consideration is that you’ll need to buy a brand-new bike in order to switch over. This, again, can be a deal-breaker for those on any kind of reasonable budget. Of course, you could sell your current bike, but it does take a lot of additional effort to do so.
On the other hand, if you’re already in the market for an urban single-speed bike, then by all means, you’re almost guaranteed to reap the rewards from a belt drive bike, and you’ll also not have to fork out too much extra for the luxury.
Final Thoughts: Gimmick or Game changer?
So, are belt drive bikes simply a gimmick or a useful product that fills a demand?
They’re certainly not a gimmick. They do fill a certain niche within certain disciplines of cycling.
But one thing is for certain: they’re not for everyone!