Braking stability

Had a trackday yesterday

and was having mayor braking stability issues

the rear seamed realy light, moved around a lot

what recomendarías do you all have, to improve on this

FRONT COMPRESSION?

FRONT PRELOAD?

REAR rebound?

geometry ?

Thanks in advance

Start with the front Sag(preload) if that is right, check the travel under heavy braking. Use a zip tie around the right leg. If there is less than 10mm of stroke left, add compression.

Are you using any rear brake, a bit can help to steady the rear, and whats your braking technique like? I have found being too aggressive and too late makes rear end chatter a lot worse.

If you add compression, it will slow fork travel, potentially slowing it down enough that you don't use the full stroke during your braking phase, which will help with stability. It will compromise edge grip.

The issue is, you are going through all the fork travel, and when you reach the end of the travel, the bike starts to pivot about the front wheel - making the rear go light and potentially sideways.

I would either decrease the air gap in your fork in 5mm increments. Or, increase spring weight in 0.25Nm increments (usually by increasing one spring by 0.5Nm).

You can increase fork preload, by at least two turns on each fork at a time, but this doesn't change your spring rate, and potentially you will still use all your travel. What it will do, is alter the geometry of the bike, which may (will) have other effects on the bike, such as how the bike turns, and stability on the throttle. However, these effects may be desirable. I would probably start with preload, depending on how my bike was already handling.

Take notes, enjoy, you'll soon work out what feels good.

Take notes.

Paul G said:

Are you using any rear brake, a bit can help to steady the rear, and whats your braking technique like? I have found being too aggressive and too late makes rear end chatter a lot worse.

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thanks guys

I will give it 1 or 2 turns of front preload

followed by 1 or 2 clicks of front compression

And to answer Paul, no, I don’t use rear brake, because of lack off riding abilities, last time I used it, I stepped on it all the way into the corner, need to better that technique, it will certainly help to settle the bike

And yes, I was going on the brakes to hard and to agressive, at the end of the day, I was more gentle, and things were a little better.

thanks for the inputs

@RODOLFO do you have the 'S' model or base? In the electronic ohlins, there is a setting specifically for "brake support" in race mode where it will stiffen up the forks noticeably when you are hard on the brakes. It does make the bike harder to tip in so it's a fine line.

If you have base model/static forks, have you had them revalved for your weight with the right airgap? These come with very little oil from factory to keep them plusher for street use, most track setups involve reducing air gap.

TomFoolery said:

If you have base model/static forks, have you had them revalved for your weight with the right airgap? These come with very little oil from factory to keep them plusher for street use, most track setups involve reducing air gap.

Click to expand...

Was going to mention this, that I reduced the airgap in my marzocchi's by about 10mm and it made a significant difference to stability over the stock setting.

TomFoolery said:

@RODOLFO do you have the 'S' model or base? In the electronic ohlins, there is a setting specifically for "brake support" in race mode where it will stiffen up the forks noticeably when you are hard on the brakes. It does make the bike harder to tip in so it's a fine line.

If you have base model/static forks, have you had them revalved for your weight with the right airgap? These come with very little oil from factory to keep them plusher for street use, most track setups involve reducing air gap.

Click to expand...

have the19 S Model

but I was running fixed suspension

will try to reduce air gap (how is this done? Adding more oil to the fork?

preload

or a bit of front compression

Have you set sag?

RODOLFO said:

will try to reduce air gap (how is this done? Adding more oil to the fork?

Click to expand...

Its easy-ish! Support the front of the ground, undo the top triple clamp screws that hold the fork leg and remove the fork caps and springs. There is a stock measurement but the easy way is to dip each leg and get an exact reading (average them if needed). Get yourself a syringe with some clear tubing of the correct length required and rest the bottom of syringe on the top of the leg and after pouring in the approximate amount, extract the excess oil. Snip the tubing as required to raise the level. If you have the time, and the bike has done some K's then replace the all the oil, but for a quick and dirty job just add it as above. Also write notes in your suspension log of the changes

Its probably easier to just remove the fork since you have to remove the spring and preload spacer and measure the oil/air gap with the fork compressed. One bottle of fork oil is more than enough for two forks, so I'd just dump out the old stuff and replace it with fresh.

They do make a tool for it.

https://www.revzilla.com/motorcycle...u5k1qcgrPKWlPiN1shoCPAkQAvD_BwE&sku_id=112415

Thanks guys

looks like i will try

compression

preload

and then oil, looks kind on hard

I'm trying not to step outside of my lane as I'm not an expert, just an informed enthusiast.

You need to start with preload and get the bike and rider sag squared away for both the front and rear. Change springs if you need to. Don't just dial more preload into the bike without knowing where you are at.

Forgot to mention forks need to be compressed to do it the way I mentioned, you can also do it approximately as the oil level variation between legs is not critical so you can measure the leg ID and use V=πr2 h or about 50mls a side for a 5mm decrease in air gap assuming the fork id is 36.

Before anyone gets excited, the oil is there for a few reasons, fluid for the damping system, lubrication and finally air gap. As long as there's enough for the first two the air gap is yours to play with. All it does is adjust the air spring and that can be very different without too much concern. The forks do not need identical amounts of oil or even the same springs because the forks are a fixed unit via triple clamps and axle. Years ago I think KTM had a dirt bike with a spring in one side only to save weight and even now we have forks with compression and rebound tasks divided between legs. That said best to be as even as possible for consistency and repeatability.