full fuel tanks effect on suspension?

[drjj]

does a full fuel tank make the suspension work differently?
does it make the front end dive more with more weight transfer going forward?
or you guys just try to keep the weight down by not filling it up to full?

cheers

[emrys74]

yeh just ask guy martin 2010 tt ouch

more weight more movement

Like having half a bag of cement to move around

just have to ride to the conditions and know where your limits are.

[pottz]

everyone tries to put in only what they need, I do the same, in theory theres no point carrying what you dont need although I honestly cant feel the difference a couple literes makes.
Full to empty id probably feel but about half down feels the same to me.

[96]

I've noticed it before. Run the litres I need, plus 2-3 in reserve. I've Been out in practice before with half-3/4 tank, and it's is a bit more to muscle around.

Though I can't say I have ever adjusted the suspension nor noticed a distinct difference in dive.

[Mr Bean]

Anyone using tank foam?

[96]

Nope... IMO, you are smooth enough, have minimal fuel, and tanks are like an I inverted tear drop, so there isn't much movement.

[drjj]

I think thats my problem, im not smooth enough.
was having trouble with my forks bottoming, added preload to stop it from bottoming but now ive only got about 15mm of sag.
thats why I was asking about dive

[Sean'o]

Full or part full tank shouldnt affect your forks that much, your problem is deeper, do youhave the right oil and right amount in your forks, are the springs right for your weight, do they have the correct amout of installed preload on them? have a chat to marty moose.

[drjj]

didnt think that the amount of fuel would make too much difference, was just curious to see if it did.
the forks were just rebuilt by someone who is highly praised on this site and 1.1 springs were installed for my 90 kgs.
during the last 4th gear no brakes I did the cable tie was passed half way so thats why I added preload otherwise ive just been ripping my tyre up which is what was happening.
was told that the forks had the right amount of oil, but im going to add some so I can take some preload out of it.
Can I cause a problem if the oil is higher than recommended?

[Shaunor8]

Why would you look at your cable tie after a no brakes session?
And if your forks were rebuilt by " someone " on this site who is highly praised, I prob wouldn't touch a thing apart from maybe a little comp or rebound. After all I'm pretty sure this " someone " knows what they are doing ( and you don't ) with the black art of suspension, I could be wrong though!
Just do a little fine tuning on your next day out I'm sure it will be sweet.

[drjj]

I looked at the cable tie because I was curious to see how far it went without using the brakes.
The day that I had ridden it before is the first time since it was rebuilt and the rear was lifting and the front sliding sideways without even braking hard.
No I dont know much about the black art, but im going to learn the hard way and its interesting to learn something new.
Ill sort it

[filbert]

Too much fork oil can result in blown seals since its designed for relief through the damping circuit before bottoming out not hydraulic lock.

You can add oil to reduce the air gap so that oil damping is more immediate but you need to know the limits, fork oil all over your brakes during a quick stop could suck.

[smeghead]

I'm around 100kgs in gear & have used .95, .975 & just recently 1kg springs. For me .95 is def too soft, .975 pretty good, 1kgs if I HTFU & ride harder to make 'em work (if I ever get to the track that is ).

Once the forks were rebuilt were they baselined to suit you on the bike, ie setting sags? When you say rebuilt was the valving changed, fork oil weight changed, fork oil level changed, these all have a significant effect on behaviour.

To upset the bike as much as you say it sounds like you must be snatching at the brakes instead of being progressive; how is the tyre tearing up?

Oh & BTW with my fat arse to drag around on a 600 I carry minimal fuel, & have on occasion run dry.

[pottz]

just to add more confusion, if the spring rate is ok and the front preload is (was?) close has it been re-shimmed? is the compression stiff enough? and just for a third one to confuse things is the rear too high?
not sure about the front sliding sideways but I find if I lift my rear rideheight by a bit the rear tends to come up under brakes.

[Shaunor8]

I looked at the cable tie because I was curious to see how far it went without using the brakes.
The day that I had ridden it before is the first time since it was rebuilt and the rear was lifting and the front sliding sideways without even braking hard.
No I dont know much about the black art, but im going to learn the hard way and its interesting to learn something new.
Ill sort it

All good, at least you are having a crack at it. I'm sure with a little trial and error and a few helpful hints along the way you will sort it out.
I did the same and I think it's the best way to learn about something. Good luck!

[chiefy36]

Anyone using tank foam?

I use foam, and minimum fuel for the session/race...

Makes shit all difference to suspension... but feels a bit smoother on change of directions, much less slosh effect... a little like riding with a pillion on the street and they lean in the wrong direction or move around too much, fuel foam just keeps the slosh effect a little smoother... nothing more...

[K1GxR]

^^
listen to chiefy. i would worship him if i could.

[Ben]

Pretty sure foam isn't in the regs?.............

[96]

This^^^

[chiefy36]

Pretty sure foam isn't in the regs?.............

Isn't mentioned in regs at all...