Look fournales shock size??
- Thread starter tricks
- Start date
Fournales shocks only have one eye, the other ends has two bolts, the centre bolt mounts the shock to the lower arm, the other smaller bolt is offset & is there to stop the shock turning & loosening the mounting bolt. They are difficult to measure in situ, the approx lengths are small 230mm, medium 250mm measured eye centre to end.
Re:
Interesting. Yes I knew about the bottom base type end the therm eye-to-eye doesn't make much sense! thanks for that!
I didn't know about this second bolt to keep things from loosening, good info!
The intention of my question is because I considered getting myself the fork and upgrade with another shock...do you happen to know wish shocks would be compatible without the need of clamping customization?
Interesting. Yes I knew about the bottom base type end the therm eye-to-eye doesn't make much sense! thanks for that!
I didn't know about this second bolt to keep things from loosening, good info!
The intention of my question is because I considered getting myself the fork and upgrade with another shock...do you happen to know wish shocks would be compatible without the need of clamping customization?
syncrosfan
Senior Retro Guru
"I considered getting myself the fork and upgrade with another shock"
Don't do it! (the upgrade I mean) I have three of those forks and I can tell you that the original shock will work best for the intended use. First of all: the original shock has an open bath damping which means they're suuper easy to service and nearly bomb-proof in reliability. (let me know if you want the shock servicing instructions). Second of all: they're fairly light(the shocks) (I doubt you'll find another aftermarket shock at similar length that's going to be lighter). Third: the shock is very skinny and long compared with traditional rear shocks, the fatty modern shocks will have clearance issues with the linkages. (I have a second generation fork in the works now, where some cretin previous owner tried to fit a regular shock and he dremeled away at the top linkage, leaving me with the task of an extensive repair job on that). Third: the leverage ratio at the linkages of the Fournales is rather low compared to the leverage ratio of rear suspensions, which results in the shocks for rear suspensions being waay over-damped in compression so the fork would feel dead and unresponsive with a modern air shock. (I learned that the hard way trying to fit a modern Rock Shox Monarch shock in a Girvin fork to replace the old steel spring Noleen shock. I managed to get the shock in but I was never happy with the way the fork felt with the modern shock, even swapped out the oil for a lightweight oil to try to soften the damping, ended up going back to the coilover shock). The Fournales shock has a lot more travel than regular rear shocks and behaves more like a high volume front fork leg than a low volume rear shock.
Yes the shocks have all different dimensions from S/M/L/XL sizes.
Don't do it! (the upgrade I mean) I have three of those forks and I can tell you that the original shock will work best for the intended use. First of all: the original shock has an open bath damping which means they're suuper easy to service and nearly bomb-proof in reliability. (let me know if you want the shock servicing instructions). Second of all: they're fairly light(the shocks) (I doubt you'll find another aftermarket shock at similar length that's going to be lighter). Third: the shock is very skinny and long compared with traditional rear shocks, the fatty modern shocks will have clearance issues with the linkages. (I have a second generation fork in the works now, where some cretin previous owner tried to fit a regular shock and he dremeled away at the top linkage, leaving me with the task of an extensive repair job on that). Third: the leverage ratio at the linkages of the Fournales is rather low compared to the leverage ratio of rear suspensions, which results in the shocks for rear suspensions being waay over-damped in compression so the fork would feel dead and unresponsive with a modern air shock. (I learned that the hard way trying to fit a modern Rock Shox Monarch shock in a Girvin fork to replace the old steel spring Noleen shock. I managed to get the shock in but I was never happy with the way the fork felt with the modern shock, even swapped out the oil for a lightweight oil to try to soften the damping, ended up going back to the coilover shock). The Fournales shock has a lot more travel than regular rear shocks and behaves more like a high volume front fork leg than a low volume rear shock.
Yes the shocks have all different dimensions from S/M/L/XL sizes.
Re:
Pics of the ends for you.
I guess that Fournales decided that as there's so little angular movement for the shock, eyes with bearings were unnecessary. The older Fournales Shark (slimmer, with aluminium legs) doesn't even have the through bolt at the top, just an elastomer mount like the later lower end.
Mk2 lower end, with anti-rotation screw and paired elastomer bushes either side of the location plate on the linkage, no pivot as such. (excuse the mud )
Mk2 upper end. M6 bolt through elastomer bush, no bearing:
Tight fit through the upper linkage Mk1, shaft is only 24mm, shock body is 35mm at its fattest:
Slightly better on the Mk2, 44.6mm clearance between arms:
General info:
The Fournales shock is pretty good as long as you don't mind the squelching sound of the oil pushing through the damping washers. As Syncrosfan says, it is specifically designed for this linkage fork, and is fully tuneable with air pressure, oil weight and adjustable damping.
They might not have ever been big players in bikes, (Forks and a rear air shock on only a few French and Italian bikes, I think) but they supply loads of performance shocks to light aircraft, scooters, motorbikes, quads, snowmobiles, race cars etc.
Mk1s have mostly brass bushings in the pivots, with grease injection ports. The Mk2 have 4x 608 sealed bearings. Probably the best, most reliable and smoothest bearings of any linkage fork, and still only 1450g a pair.
One last cautionary note: Try to get a set including the clamp-on v-brake mounts. The disc mount is OK for bolt spacing, but is pre-ISO2000, so not the standard 4mm offset from the dropout and won't fit current brakes (whatever the vendor says :roll: ). The disc mount needs some serious work to fit ISO2000 calliper (mill the 4mm off the disc tab face and shave a chamfer onto the bottom edge near the hub to clear the rotor bolts). Compatible brakes, hubs and rotors can be found, but not that easy. At least if you've got the v-brake mounts, you can ride the fork while you look for a disc brake
All the best,
Pics of the ends for you.
I guess that Fournales decided that as there's so little angular movement for the shock, eyes with bearings were unnecessary. The older Fournales Shark (slimmer, with aluminium legs) doesn't even have the through bolt at the top, just an elastomer mount like the later lower end.
Mk2 lower end, with anti-rotation screw and paired elastomer bushes either side of the location plate on the linkage, no pivot as such. (excuse the mud
)Mk2 upper end. M6 bolt through elastomer bush, no bearing:
Tight fit through the upper linkage Mk1, shaft is only 24mm, shock body is 35mm at its fattest:
Slightly better on the Mk2, 44.6mm clearance between arms:
General info:
The Fournales shock is pretty good as long as you don't mind the squelching sound of the oil pushing through the damping washers. As Syncrosfan says, it is specifically designed for this linkage fork, and is fully tuneable with air pressure, oil weight and adjustable damping.
They might not have ever been big players in bikes, (Forks and a rear air shock on only a few French and Italian bikes, I think) but they supply loads of performance shocks to light aircraft, scooters, motorbikes, quads, snowmobiles, race cars etc.
Mk1s have mostly brass bushings in the pivots, with grease injection ports. The Mk2 have 4x 608 sealed bearings. Probably the best, most reliable and smoothest bearings of any linkage fork, and still only 1450g a pair.
One last cautionary note: Try to get a set including the clamp-on v-brake mounts. The disc mount is OK for bolt spacing, but is pre-ISO2000, so not the standard 4mm offset from the dropout and won't fit current brakes (whatever the vendor says :roll: ). The disc mount needs some serious work to fit ISO2000 calliper (mill the 4mm off the disc tab face and shave a chamfer onto the bottom edge near the hub to clear the rotor bolts). Compatible brakes, hubs and rotors can be found, but not that easy. At least if you've got the v-brake mounts, you can ride the fork while you look for a disc brake
All the best,
Attachments
syncrosfan
Senior Retro Guru
I do have spares for both the clamp-on V-brake mounts and the disc mount. If anybody needs either let me know.
The Mk2's are the ones to get. The Mk1's work fine but the action of the bearings in the Mk2's is amazing (I just replaced the bearings on mine). As Danson67 said, the shock might squelch a little but works really well. I would recommend to do an oil-change at least yearly since it's an open bath system and the oil will get contaminated.
The Mk2's are the ones to get. The Mk1's work fine but the action of the bearings in the Mk2's is amazing (I just replaced the bearings on mine). As Danson67 said, the shock might squelch a little but works really well. I would recommend to do an oil-change at least yearly since it's an open bath system and the oil will get contaminated.
Thanks guys. Very good info! Still talking about shock alternatives, What is the stroke length for the original? I'm assuming it also depends on the fork size? So...if I could find a shock with the same stroke, figure it out a way to attach the bottom (I have access to 3d printing) could work fine?
syncrosfan
Senior Retro Guru
I think the stroke length should be the same on all of them, it's just the longer ones have a longer shaft. It's fairly long stroked compared to regular shocks but I don't have my bike with me today to measure it up. I hope you have access to metal 3D printing as I wouldn't dream to use a plastic part on such a crucial connection (the plastic part will give you an idea if the connection works though). You might need to look into the longest stroked rear shocks you can find.
I do have a Hurrycat Vorace fork as well which is the pinnacle of weird looking suspension forks and this one does take a regular sized SID shock from factory. Definitely heavier than the Fournales and ugly as sin but it offers 100mm travel!
I do have a Hurrycat Vorace fork as well which is the pinnacle of weird looking suspension forks and this one does take a regular sized SID shock from factory. Definitely heavier than the Fournales and ugly as sin but it offers 100mm travel!
syncrosfan":2bd98vqa said:
Of course, stainless steel 3d printing! I've been having a lot of fun doing some CAD modeling lately...and mess with the Fournales would be pure joy...I have some ideas in mind for a special tuning on this fork.
if you could please tell me the shock stroke length someday would be great! thanks
