Kona Cowan Frame; Rohloff Compatible??

[Beave]

I've been using my Rohloff on my full suspension bike for a couple years now. While everything has been excellent, I have been leaning towards a hard tail for my next bike. An added bonus to this change would be the removal of the all-to-derailleur-like chain tensioner.

But after browsing the Kona website today, I noticed they have the Cowan full suspension frame, with adjustable dropouts that would allow the fitting of Rohloff specific dropouts. The frame is said to be for either single or multi-speeds.

So my question for the geometry experts out there; Would this frame work with a Rohloff hub, Rohloff specific dropouts, and NO chain tensioner?? In this four bar linkage, would the chain grow or shrink as the swingarm moved through it's travel??

Check it out:

http://www.konaworld.com/FRAMES/2K7_COWAN_Frame_big.jpg

Thanks in advance for any help,

Beave

[Dave Whittle Thorn Workshop]

Its a non URT so you would need a chain tensioner, you would be best with a Rohloff speedbone as a torque arm, see the speedhub slector on Rohloff.de

[Beave]

Interesting,

I've spoken to a handful of folks about this, and it seems that I would not need a tensioner for this bike, as the pivot point is srrounding the bottom bracket, meaning the chain stays a consistant length throughout the travel of the swingarm; Looks like I've found my next bike!

Beave

[bike_the_planet]

quote:Originally posted by Beave

Interesting,

I've spoken to a handful of folks about this, and it seems that I would not need a tensioner for this bike, as the pivot point is srrounding the bottom bracket, meaning the chain stays a consistant length throughout the travel of the swingarm; Looks like I've found my next bike!
Beave

The only time you don't need an external chain tensioner is if you have a non-sus rear triangle and either a) horizontal droputs so that you can precisely adjust the length of the chain by moving the rear wheel back and forth, or b) an adjustable, eccentric bottom bracket as used by Thorn.

If you have vertical rear dropouts and no eccentric bottom bracket you will have to have a chain tensioner. If you have a fully sus rear triangle such that the chain length varies as your suspension moves up and down you will definitely need a chain tensioner even if you have an EBB!

[bike_the_planet]

Beave - I've just seen the picture of the frame you want. Looking at it, I believe that the chain length won't change as the suspension bobs. Therefore, if it is fitted with adjustable (horizontal) droputs that allow the rear wheel to be moved back and forth, then you don't need a chain tensioner. But if you replace those dropouts with Rohloff specific OEM droupouts, which are vertical, you will need a chain tensioner. I presume that rohloff vertical dropouts do include a mounting hole to attach a chain tensioner - I haven't checked.

Hope this clarifies.

Cheers

[PH]

If as it appears the frame between the BB and dropouts is rigid I can't see how it would be any different from a rigid frame.

This is a standard Rholoff OEM dropout, there may be others, I haven’t seen them.

It doesn't need a chain tensioner or a torque arm and looks to me like it would fit the Kona frame.  A friend used these and a Rohloff on an On-One MTB designed as a single speed.  I think On-One manufacture the dropout or at least supply them.

[bike_the_planet]

quote:Originally posted by PH

If as it appears the frame between the BB and dropouts is rigid I can't see how it would be any different from a rigid frame.

This is a standard Rholoff OEM dropout, there may be others, I haven’t seen them.

It doesn't need a chain tensioner or a torque arm and looks to me like it would fit the Kona frame.  A friend used these and a Rohloff on an On-One MTB designed as a single speed.  I think On-One manufacture the dropout or at least supply them.

But how do you adjust the chain length as the chain wears if you don't have an EBB? The only OEM dropouts the negate the need for a chain tensioner are the horizontal ones, because adjusting the wheel in these will lengthen/shorten the chain.

Cheers

[pdamm]

There are horisontal slots where the dropouts bolt to the frame allowing you to move the dropouts backwards and forwards and thus taking up any slack in the chain.

There is a bit more messing around with this mechanism since you may also need to adjust the position of the brake pads as the wheel moves backwards (if you have V brakes or canti's).  Also you can get the wheel out of alignment if you accidentally move one side more than the other.

But playing around with bikes is often fun

Peter Damm

[Beave]

Thanks for the replies folks,

From all I have heard here and elsewhere, this should work just fine. No chain growth, adjustable dropouts and the slight incline of Rohloff specific dropouts should keep the old chain tight and happy. I guess I'll find out after my current bike dies.

Thanks again,

Beave

[nicknoxx]

Sorry to drag this up, but I've only just found this thread.  

You won't need a chain tansioner with a Cowan DS. I've got a Kona A which is similar but lighter (think XC not jump/park,4X). Mine's the older version without disc mounts but it works brilliantly with a Rohloff hub.