Front & Rear Discs for K2 4000 or 856?

[DugB]

Hello all,

I know RDS makes rear swingarm Hammerheads for both the K2 4000 (Easton ProActiv carbon rear fork) and 856 (with GLS rear fork), but I haven't seen any disc brake adaptors on Callum's site for the Noleen Crosslink or Girvin Vector II front forks. Has anyone bought such an adaptor from RDS? If not (and they're not available from Callum), has anyone else figured out a way to run front discs with either the 4000 or 856?

Thanks!
- Doug

[Old Proflexer]

there's a few in the gallery -

[orange]

Callum doesn't do one, but OP's is the bizz.

[orange]

I think Mr 752 did one too.

[DugB]

Thanks for the info! Do you all mean that other people make 856 rear disc mounts, or that someone makes a Vector II or Crosslinbk disc mount? Just wondering...from the Hammerhead installation instructions the 856 rear mount doesn't look too complex.

- Doug :-)

[Old Proflexer]

buy one (trust me on this one) for the rear on an 856
it's easier than making your own - the original part #5996 from ProFlex is no longer available.

front disc mount fabrication basic instructions are in the 'how tos' section

original part #5996 with Rohloff



OP



(the basics on 4500)

[shovelon]

original part #5996 with Rohloff


  I have never seen that before. It's really nice!

Terry

[DugB]

Unfortunately I don't think the 856 rear mounts are available any longer...Callum isn't making them, and they're sold out on his site. I may pick up a 4000 mount, though, as he still has them. Also considering hydraulic rim brakes...I'm just not liking the feel of the V brakes I currently have.

So I still haven't heard anything on the fronts...anyone have info on mounting discs on Crosslinks? Callum indicated that doing so on vector IIs might not be a great idea.

- Doug :-)

[rapiddescent]

sorry guys,

mike and I decided to stop making HammerHeads a while back and we're just running down stocks.  The 856's are now getting a bit old to spend 00's of dollars on upgrading to disks when you can just buy a whole new bike for less.  Also, we made them in Sweden using top quality steel, the US Dollar sank so low against the Kroner that they just were economic for most of our USA customers.

as for the front.  I would recommend NEVER adding front disks to a vector or cross link aluminium fork.  many were destroyed at Girvin and we broke one as well testing.   I was also involved in when Girvin told Hope (UK Disk brake guys) to stop making vector kits.  OP and Mike both made front versions for the carbon forks - mike doesn't have his anymore (bike was stolen) but it looks like OP's is still working.  I think this is more down to the skill of adding it to the carbon crosslink fork than anything.  I would worry about a fracture at the top eccentric bolt hole on the left leg.

by the way: I'm running around trying to buy up old carbon frames for some new stuff for these bikes - if you broke yours then I will buy the bits of frame off you.

thanks
callum

[Mr752]

Below area couple of pictures of my efforts for the front & rear disc mounts for Crosslinks(Alu) and a 856 frame
Take careful consideration before you start on the Crosslinks, everything Callum said about fork failures needs to be heeded and any designs copied are at your own risk.
Whereas OP bonded his mount to carbon legs, mine is to Alu using an Araldite fomulated for Alu to Alu.
I've took it out for a fair few thrashes now and alls well, Juicy 5's sqealed abit before bedding in.
On the back I used 3mm Stainless steel and stainless tube for spacers to get the caliper alignment right.



Mr752

[kondilemma]

On the back I used 3mm Stainless steel and stainless tube for spacers to get the caliper alignment right.

Where would I find stainless tube for making spacers?  I'm using 6mm alum plate for my rear mount and want something more solid than a stack of washers.

-kond

[rapiddescent]

if it helps, I've still got loads of 7mm and 8mm cylindrical spacers that we sold with hammerHead kits.   7mm and 8mm are the thickness of the dropouts on the left side of most proflex/k2 bikes.  sometimes they used 8, sometimes they used 7.

Mr752> I would consider stengthening the top left-leg bolt area in the same way you've strengthened the lower leg and also there is a weakness point just below the bottom left leg eccentric bolt (this is where the leg bends the most).  Also - if you can use a F. tight front hub setup.

callum
rds

[Old Proflexer]

I made a couple of front mounts that went on to aluminum legs - just made the support longer to distribute the load. 
They are pretty much identical to the ones on my carbon units.

Didn't have any failures even under heavy breaking but that thin aluminum isn't designed to handle that stress. 
Seemed to do so for my xc purposes. 
Those links have been given a spot on the wall of the garage.

Never saw a picture of Mike B's version -

OP

here's a reverse side pic of the Rohloff setup -

[kondilemma]

as for the front.  I would recommend NEVER adding front disks to a vector or cross link aluminium fork.  many were destroyed at Girvin and we broke one as well testing.   I was also involved in when Girvin told Hope (UK Disk brake guys) to stop making vector kits.  OP and Mike both made front versions for the carbon forks - mike doesn't have his anymore (bike was stolen) but it looks like OP's is still working.  I think this is more down to the skill of adding it to the carbon crosslink fork than anything.  I would worry about a fracture at the top eccentric bolt hole on the left leg.

this is coming from a Physics flunky-- 

but in a disc brake setup on alum vectors or crosslinks, would any strength be gained by adding one of the old- fashioned 'brake boosters' or equivalent to the rim brake mounting studs?  At least the legs would be tied together a bit more.   
-kond

[DugB]

I get the feeling the issue is the thin walled tubing used for the legs...that unless the braking force is spread out over a large area (as with the bonded adaptors in the pics) all the force would be in too small an area...seems like the braking force could push a caliper adaptor into the thin tubing, or through it at worst, essentially collapsing the leg...just envisioning it gives me high pucker factor.

I'd also think whatever support you used would have to be must stronger than the leg's tubing...

The idea is a good one, though...if I get carbon gels I just light try it...someday. In the meantime, my Magura HS33's arrive today ;-)

- Doug :-)