Forks question

[Locksmith]

As you probably know I've put ohlins springs in my forks !!!

My question is, I'm using the cable tie method to see how much travel I'm using. Is the bottom of the chrome tube the actual suspension bottom point or is it a few mm upwards (or more)

The tie is currently around 15mm from the bottom of the actual tube after a mornings hard riding.

 

[ToastedBlue]

on my STR it's about 15mm

 

[Kinjane]

On standard preload the exposed tube measures 140mm. The forks have 137mm of total travel. So that's an absolute minimum of 3mm. Plus some more from the rebound.

 

[flipper]

Is that 140mm measured at full extension? Or with weight on the wheel? Ie did you account for static sag?

I would expect more than 3mm. More like 12 to 15 but I'm nowhere near my bike to check it.

 

[Kinjane]

Full extension, wheel off the ground.

That 3mm clearance figure means there is absolutely no chance of contact between the moving and static parts of the fork, especially since the forks don't actually have 137mm of downward travel.
I'm sure the minimum is 11mm of clearance between the dust seal lip and the casting because my 3mm wide cable tie has never left anything less than an 8mm gap on its underside - unless some kind soul decided to lower it whilst the bike was left unattended.

Ultimately the only way I can think of to obtain a definitive answer it is measure the distance with the fork internals removed.

 

[flipper]

I think your numbers are right. Removing the internals won't help as the dust seal then meets the bottom casting

 

[flipper]

I've just had my forks apart again this afternoon so I measured this.

With no spring and the forks reassembled, fully compressed so the bump stop must be bottomed out, I measure 14mm of chrome showing.

 

[Locksmith]

I've just had my forks apart again this afternoon so I measured this.

With no spring and the forks reassembled, fully compressed so the bump stop must be bottomed out, I measure 14mm of chrome showing.

So does that mean if I want 15mm of travel left (for unexpected pot holes etc while braking), I need approx. 29mm of chrome under the cable tie? (less the width of the tie)

 

[Kinjane]

The rubber bump stop will compress under load, but it wouldn't be a bad thing to use 14mm as your minimum figure.

The 29mm would be the amount of chrome showing measured to the top of the cable tie.

 

[flipper]

So does that mean if I want 15mm of travel left (for unexpected pot holes etc while braking), I need approx. 29mm of chrome under the cable tie? (less the width of the tie)

I would say so, yes.

 

[Locksmith]

Excellent, thanks guys

 

[flipper]

When you had the springs fitted what oil level was set?

 

[marthy]

When you had the springs fitted what oil level was set?

130mm before springs installed. 130mm is not one of those magic number, it works well for me. I won't go over 120 but 130mm is a good start.

Sorry... I replied to the wrong thread...

 

[Locksmith]

When you had the springs fitted what oil level was set?

What ohlins specified, 145 mm

 

[Kinjane]

If only the springs have been swapped, shouldn't the forks still require OEM capacities for the fluids @ 147mm left, 148mm right ?

 

[Locksmith]

Search me, the ohlins spec just said 145, no mention of different for both sides either?

 

[flipper]

If only the springs have been swapped, shouldn't the forks still require OEM capacities for the fluids @ 147mm left, 148mm right ?

No. Oil height, although requiring a minimum, is a tuning parameter for the forks. Raising the oil level will increase the overall combined "stiffness" of the coil spring and air spring.

Read more clever shit here:

Peter Verdone Designs - Oil Height