Monday, 16 March 2009

The belt drive: Farewell to dirty chains?

I surrender, and confess: This is the chain of my personal bicycle after this morning’s commute. Embarrassing, isn’t it? Now you can get several urban bicycles featuring a silent, maintenance-free belt drive instead of the metal chain. The question is: Will they make you happy?

You know it, I know it: Worn-out, brown and rusty bicycle chains are the sure sign of an ignorant, lazy bicycle owner. Anyone will know him by the creaking, squealing signals from his suffering drivetrain – leaving no doubt about this person’s non-existent level of insight and responsibility regarding bike maintenance.

But hey, I’m supposed to be a bike geek! I know all the fine details of chain, cog and lubrication technology, I have the required remedies on hand in my own home, like a true bike geek should. But I’m also a bike geek with a full time job, several kids to play with, lot of friends to meet, other passions to entertain, no particular love for wrench-related work and of course the usual shortage of sleeping hours.

That’s why I don’t love the chain drive on my own bike.

That’s also why I was very intrigued when I first heard of the belt driven bicycles that have appeared during the last years. This season they are finally entering the mainstream bike market. Have a look at it in this YouTube-clip from the Associated Press:

This polyurethane belt strengthened by small carbon fibres claims to deliver twice the lifespan of an ordinary chain, at about a third of it's weight - while requiring no cleaning, no lube, no maintenance, and will thus not decorate your pants with greasy black oil prints. It will not stretch, and promise to stay as efficient as new all the way.

On top of it all: It's silent. No creaking, no squealing. No embarrassment.

Intruiging, isn't it?

Gates Carbon Drive (mostly known for belts used in car engines) is the manufacturer who are now cooperating with several bicycle makers on the belt drivetrain. Small brands have been into belt drive for years, but the concept didn’t really catch public attention until Gates and Spot Brand launched mountain bike prototypes three years ago.

The German brand Nicolai also has a Gates belt-driven commuter bicycle on their 2009 menu, the Argon TR. A very very nice, but also a very high-end, expensive niché model:

The first major mainstream player to join the belt club is Trek Bicycles – with two urban bicycles featuring the Gates Carbon Drive belt for 2009: The single-speed hipster Trek District (with orange rims below), and the sensible, geared commuter Trek Soho.

I’m way too uncool to even consider the oh-so-trendy District, and thus fell directly for the dull grey and apparently boring Soho instead. Boring? No! It must be the perfect commuter!

Look: Eight internal gears in the rear Shimano Alfine hub, unaffected by sand, dirt or weather conditions! Internal roller brakes, steadily controlling your speed regardless of rain or snow! Trek even supply decent fenders! And topping it all off: A Gates belt, instead of last years traditional metal chain.

All nice and dandy, then?
I’m truly fascinated, but not totally convinced.

The belt itself are obviously better suited to such an exposed workplace than the good, old metal chain. It will not stretch, break or rust, and – unlike the love-demanding chain – keeps totally silent without maintenance.

But looking at the whole picture, the comparison becomes more complex:

* The belt can not be split, like the chain. And since it is trapped within the frame tubes, the frame itself has to split at the rear wheel axle in order to install or change the belt. This means that you’ll need a specially made or modificated frame, where a chain can be used on all kind of existing frames and drivetrains. On the other hand: The modification is not a huge one, and could easily become a standard feature on future bicycle frames.

* The belt can not be used on your existing drivetrain. You’ll need special cogs front and rear, specifically designed to fit the belt. This means spare parts will be hard to find, if the system should fail.

* The belt can not be used with outboard derailleur-based gear systems. It naturally can not move along a set of cogs, and thus requires a single speed setup (light, but narrow range of use) or an internally geared hub (broader range of use, but heavier than ordinary outboard drivetrains).

* This last point immediately raises another one: You can only compare the belt drive to a chain drive when both are used in a single-speed or internal hub system. In these single-cog drivetrains, the state of the chain is functionally less crucial than in outboard systems – since it only has to transfer power between two cogs, not having to shift smoothly between cogs at the same time.

* The belt drive is more expensive than chain-based systems. Last year, the 2008 Trek Soho model had an ordinary chain drive, but better and stronger disc brakes. This year, the 2009 model get you a Gates Carbon Drive system, but less effective and cheaper roller brakes as a trade-off.

In this case, I prefer better brakes, even if accompanied by an embarrassing squeal from my dry, red chain.

The Spot Highline - a commuter bike from the company that launched the belt drive way ahead of Trek, but with far less marketing power.

The Gates belt cog, designed to press dirt straight through - and keep maximum grip in all conditions (click picture to make it readable)


peterjerome said...

As a cyclist who rides for environmental reasons I have a few concerns. Like carbon forks, does a carbon belt probably need gobs of energy and produce scary toxins during the manufacturing stage? And what about recycling when the belt is done? An old chain can be reincarnated into many things.

mindcaster said...

how about a bike with a fully enclosed chain guard? Maintenance/care-free, no dirty pants, etc etc. I hear the Danes and Dutch have been in love with that type for over a century :)


Kai Grieg said...

Great blog! I have had a bike with blet drive for two years. My best commuter bike ever. I bought it at Den grønne sykkel in Bergen (norway). THey might have an other one for sale as well:

With better brakes til will be the perfect commuter bike. IMO.