jiiiiiiiiiiiiii gannnnnnntoooooooorrrrrrrrrrrrrrr

[JohnnyO]

Yes Geoff told me yesterday they are 50mm. Modern bikes have fork legs between 45 and 50mm.

[Ji Gantor]

I think the Huskys have the largest at 51 but I did not see that coming.
Wow they were a head of their time.

Ji

[JohnnyO]

The Husky's are 50mm, the factory KTM forks the guys here are using are 52mm! Massive.
Anyway it will be a challenge to find a set of suitable Simons clamps.

[motomaniac]

Johnny are you sure.
Most bikes today are only 48mm.

Ji

About 20 years ahead of thier time .!

[caps 999]

yeh hes right that means the only clamps that would come close are ohlins ones

[JohnnyO]

The Ohlins clamps will still have the wrong offset to suit the small amount of offset on the Simons forks.

[caps 999]

true but with some maching they could be made to work

[motomaniac]

true but with some maching they could be made to work

The stem hole would be outside the clamp for it to work .You need alot more offset not less.

[JohnnyO]

If you look at a pair of those Simons you can see they are almost like old school in-line forks with the axle mounts offset only a small amount compared to any other leading axle forks.
I don't think you will find any triple clamps with the right steering offset to suit them.
All the other upside down forks have the axle mount in front of the fork leg. Any clamps other than Simons will change the trail significantly.

[Lozza]

Place bike on car jack, with bottom frame rails supported.
Extend/lower jack until headstock angle reads the same as manual(check with an ANGLE GAUGE)
Place wheel and fork assembly at standard wheelbase length. Chock tyre for and aft.
Transfer angle gauge to fork, with tyre on correct wheelbase.
Measure distance from fork leg to steering stem.
Offset will be the measured distance plus radius of the dia of the fork leg and radius of the steering stem.
That is the required offset.

Increase trail, decrease headstock angle, decrease trail increase headstock angle, is a bit of an old rule of thumb.

[sa63]

i cocked up an an ebay bid (another story) and have a DRZ 400 bottom triple clamp which takes a 49 mm fork. If its on any use it owes me $ 50...

[motomaniac]

Place bike on car jack, with bottom frame rails supported.
Extend/lower jack until headstock angle reads the same as manual(check with an ANGLE GAUGE)
Place wheel and fork assembly at standard wheelbase length. Chock tyre for and aft.
Transfer angle gauge to fork, with tyre on correct wheelbase.
Measure distance from fork leg to steering stem.
Offset will be the measured distance plus radius of the dia of the fork leg and radius of the steering stem.
That is the required offset.

Increase trail, decrease headstock angle, decrease trail increase headstock angle, is a bit of an old rule of thumb.

Lozza you left out the critcial factor that Johhny O is talking about.The trail is dependant on the axle position.Your method works if the axle is inline with the forks only.With axles that are offset you have to include that.The thing with the Simons forks is that the offset of the axle is very small compared to the modern USD's.Thta s why the modern USD triples won't work.

[JohnnyO]

Place bike on car jack, with bottom frame rails supported.
Extend/lower jack until headstock angle reads the same as manual(check with an ANGLE GAUGE)
Place wheel and fork assembly at standard wheelbase length. Chock tyre for and aft.
Transfer angle gauge to fork, with tyre on correct wheelbase.
Measure distance from fork leg to steering stem.
Offset will be the measured distance plus radius of the dia of the fork leg and radius of the steering stem.
That is the required offset.

Increase trail, decrease headstock angle, decrease trail increase headstock angle, is a bit of an old rule of thumb.

Lozza you left out the critcial factor that Johhny O is talking about.The trail is dependant on the axle position.Your method works if the axle is inline with the forks only.With axles that are offset you have to include that.The thing with the Simons forks is that the offset of the axle is very small compared to the modern USD's.Thta s why the modern USD triples won't work.

You got it Maniac

[Lozza]

Yes place straight edge through centreline of headstock to the ground, plumb-bob though axle centreline to ground distance on the ground is trail. I didn't say anything about modern USD triples, that's how you work out offset for custom triples.