Tuesday, September 20, 2011

9 teeth is all you need.

A little while ago, i posted about new school micro drive mtb clusters. There are lots of reasons why they make sense. Suffice to say that with a 9, 10 and 11 tooth at the high range on the cluster, going down to 32, 34 or even 36 with 9 or 10 speeds gives a huge spread and although the 9 tooth might put more strain on the chain and be slightly less mechanically efficient in lab conditions, covered in mud and given how lttle time you spend in your top gear, and how low the torque is in that gear (admit it!), i doubt durability will be that much of an issue...but think of the benefits....!

(pic is Pinkbikes, from an article about this custom DT freehub body for Sam Hill and the rest of the Specialized DH boys bikes. I'm pretty sure this is a Shimano Capreo compatible system).


For the record the development (as in the distance a 26" wheel bike moves with one rotation of the pedals) for a 36:11 gear is 7.053m. Let's say you had a block with 9 teeth on the smallest sprocket, the same development, more or less, is achieved with a 30 tooth front cog (7.183m). So imagine how real-world useful a 32 or 34 chainring with a 9-34 or even 36 rear cluster would be?

(pic is VitalMTB's from their excellent interbike coverage).

Enter Canfield Brothers. With a can-do attitude, and a broad range of mountain bikes in their portfolio (including a new interest in 29er am hardtail set ups), they are bringing to market a hub that will work on most rear standards (135mm, 150mm, 157mm and i believe qr or 12mm and 9 and 10 speed compatible) that has a freehub body optimised to run the bottom 3 sprockets of a Shimano Capreo cassette. If you haven't heard of the Capreo group, it was designed to work with small wheel road bikes - think folders, Bromptons etc. 'Course with a small wheel, you need big gear ratios to give you resonable development. So, you use massive chainrings or small clusters. Bingo. The 11 tooth has a female fitting over the end of the cassette body splines (look up at that top pic) and it has male splines that the 10 tooth fits onto. This in turn has male splines that the 9 tooth fits on to and there is an external lockring that threads onto the end of the stepped down section of the freehub body. You only lose a small amount of lateral space for the bearings that typically fit in the freehub body.

I want one...or maybe 2...yes, i hope DT market the freehub body so i can use my DT hubs, but i think i'll be getting one of the Canfield hubs when it hits the market. With Hope also playing with this system, i doubt it will be long until really wide range 1x10 set ups are common place.

1 comment:

cy@cotic said...

Capreo's 9spd spaced though, and having 11t as your 3rd sprocket's going to give you some huge jumps higher up. Not convinced.