Nothin’ new in t’ world - linkage forks...

[danson67]

Oh yes, the 1992 APB, and it's rebadged Land Rover variant.



Strangely they don't get many column inches around here.
Sub-con manufacturef by Pashley IIRC.

All the best,

 

[2manyoranges]

and Reynolds iirc....

 

[TheAwesomePossum]

What about the Birdy? You see them every now and then on german streets, about as frequent as you can spot a brompton. I'm still curious how it actually rides

 

[Dr Dremel]

What an awesome thread! Never knew there were so many designs of linkage forks. One omission though: The Lawwill Leader! First read about them in 1992, never saw one with my own eyes. I think they were later manufactured by Control Tech, no idea on the earlier models.


image credit: orme.tv

 

[danson67]

What about the Birdy? You see them every now and then on german streets, about as frequent as you can spot a brompton. I'm still curious how it actually rides

Although there's no reason for them not to work fine as a suspension fork, or at least take the edge off things, I think the main motivation on the Birdy was to get that pivot point on the leading link as far back as possible.
This allows the front wheel to get a good fold under the main frame without the pesky sideways hinge that Brompton etc have:



All the best,

 

[TheAwesomePossum]

This allows the front wheel to get a good fold under the main frame without the pesky sideways hinge that Brompton etc have

Ha! Never thought of that, another reason why one might want to develop a linkage fork..

 

[danson67]

What an awesome thread! Never knew there were so many designs of linkage forks. One omission though: The Lawwill Leader! First read about them in 1992, never saw one with my own eyes. I think they were later manufactured by Control Tech, no idea on the earlier models.

The OP did mention them in passing, so I didn't put them on my list.

A familiar setup...here's mine on the RS-1 :



The original Lawwill Leaders had a welded or brazed steel fork legs, with the standard shock mounted onto a pivot on the underside of the handlebar stem and a swingarm linkage at the crown to control fore/aft movement.
The paired, but out-of-parallel and different length linkages give a vertical axle path, so almost no change in trail throughout travel.1990/91



This changed to the machined crown, linkages and aluminium legs of the Leader2 when Control Tech got on board. Proprietary shock rigidly mounted to the crown, with a pivot/eye at the bottom of the shock:1992



Then there is the Leader3, which is pretty similar except for the side plate trunnion mounting for the shock, so now has a rigid unicrown front fork, with a pivot on the shock body to allow it to rock fore/aft slightly during travel. More rigid and avoids the side loadings on the shock shaft:



Mert Lawwill ran a few different brands of disc brake on his prototypes, including Shimano and MountainCycles ProStop.



The one on the blue RS-1/Leader2 is the later Hope mechanical that Fisher adopted for their bike, rather than the p**s poor ProStop that was used at the start of production.

Here are a few in Mert's own workshop:



All the best,

 

[elite504]

Great pictures!
Shock unit on the Mk3 is by Risse.

 

[danson67]

Great pictures!
Shock unit on the Mk3 is by Risse.

I think they are all Risse shocks.
The Leader2 one at least...Risse serviced mine only a few years ago and were happy to see it still working after almost 30 years.

All the best,

 

[Dr Dremel]

Love it! Thanks for the comprehensive overview, definitely my favorite linkage fork (albeit just from the looks). I remember being baffled by the Fisher RS 1, that looked like the future.