Dirty, noisy chains and dirty, fragile rear derailleurs are two features of modern mountain bikes that could certainly stand to be made obsolete. Well, the Cavalerie line of full-suspension MTBs does away with both, replacing them with a Gates Carbon belt drive and an Effigear gearbox. Launched last year in its native France, Cavalerie is about to get a boost in profile, as it commences distribution in North America.
The Gates belt drive is popping up with increasing frequency on a variety of types of bicycles, as it's much smoother and quieter than a chain, plus it doesn't require lubrication or cleaning. It can't be used with traditional derailleurs, however, which limits its applications to either single-speeds or bikes with non-derailleur gearing systems.
One such system is the Effigear. It's actually been in development since 2004, although it arrived at its present incarnation relatively recently. If it looks at all familiar, it's because it resembles the Pinion gearbox, which is already available on a number of mountain bikes.
Like the Pinion, its advantages over a rear derailleur include the facts that it's sealed against external contamination, it requires very little maintenance, it's much less subject to damage (there's no bendable bit hanging down), gears can be shifted while the bike isn't being pedaled, and it moves weight from the end of the bike to the middle, for better stability and less unsprung weight. That last point is one of the reasons we don't see more sealed hub transmissions on mountain bikes.
Also like the Pinion, however, it's heavier than a derailleur, plus it must be built into the frame – it can't just be added to an existing bike, or swapped with something else.
One of the differences between the two is the 444-percent 9-speed (maximum) gear ratio on the Effigear, as opposed to 636 percent and 18 speeds on the Pinion. The Effigear, however, can utilize three types of shifters (trigger, sequential twist or traditional twist), as opposed to the Pinion's one. More importantly for the Cavalerie bikes, the Effigear's integrated suspension pivots allow it to be used with a belt drive on full-suspension bikes – the Pinion can only be paired with a belt drive on hardtails, except for a clever exception or two.
As for the bikes themselves, there are three models: the 37.25-lb (16.9-kg) Falcon downhill bike, that features 200 mm of fork travel and the choice of a 6- or 7-speed gearbox; the 36.5-lb (16.6-kg) Squirrel freeride, with 185 mm and nine speeds; and the 31.5-lb (14.3-kg) Anakine enduro, with 160 mm of travel and 650b-sized wheels. Pricing for the Anakin has yet to be announced, but the Falcon and Squirrel are available to American and Canadian buyers now, both for US$5,750. They're available through Philthy Bikes, which is handling North American distribution.
If you want to check them out in person, they'll be making their stateside debut at the Sea Otter Classic festival and expo, from April 10 to 13 in Monterey, California.
... and just for the record, Cavalerie isn't the only manufacturer to have adopted the Effigear gearbox. It's also found on full-suspension bikes made by Germany's Nicolai Bikes, among others.
Sources: Philthy Bikes, Gates Carbon Drive, Cavalerie Bikes
In answer to your question, none of them overlap - just look at the photo (and its noisy spur gear design).
Actually, i have rear hub shifting on my bent. I d be tickled just to get a belt and pulleys for it. Lubing is a PITA that I d like to do with out.