Geometry Issues!!!

[schmiffee]

I recently came acorss and purchased what I believe to be Ridgi's old TRX as I want to track bike it, and it had parts that I wanted for my fighter project, but in the process I am having a problem.

I have installed the forks on my fighter frame as pictured below, and now that they are on I have found that when riding in a straight line it will steer great (no notchy-ness of the steering-head bearings at all) but when I try to counter-steer into a corner (to lean in), the bike really fights me and I have to put in heaps of effort to turn.

FighterFront.jpg

When I measure it up, there is a vertical difference in height between the r1 front and standard front of 10mm (measured vertically from the ground to the bottom of the headstock) - Fighter front 710mm and the standard (Track) front 720mm.

FighterTopClamp2.jpg

TrackTopClamp.jpg

Is there something I have missed? Probably something stupid, but I have thought and pondered but can't figure it. I don't understand why the forks worked perfectly when fitted to the other bike and not on the fightered frame - the only difference is I replaced the steering-head bearings.

As a side note, I measured the length of the forks on both bikes and the standard forks came to around 760mm whereas the forks came to about 705mm...is this normal.

[fung]

perhaps the dogbones on the old frame were shorter, thus giving the 'neutral' turn in.
longer bones will make it 'lazy' to turn in.
similarly, too hard in the front in relation to the rear will make it 'fight' turn in.
so the old frames rear shock might have been set harder in relation to the new forks.
cheers
fung

EDIT : i just looked at the pictures again and i noticed the TRX preload is on the soft side, and the R1 forks are set 'harder'.
what are the damping settings ?

[schmiffee]

Good point about the dogbones...will check out tomorrow.
Also good point about rear shock as the one from Ridgi's bike is buggered...doesn't turn.

Regarding fork settings - TRX have new race tech springs and emulators in them and were installed and set up by a mechanic...havnt had a chance to play with them yet. R1 forks are as thy came of the other bike...any suggestions on this welcome too

[fung]

firstly find the oem owners manual for the model bike the forks came off online.
this will give you the std settings.
perhaps try these but a bit softer preload at first, as japanese bikes seem to be oversprung and underdamped.
not knowing your oil weights and airgaps is a bugger.
maybe its time to clean and refill. at least you will know whats what eh and set it up for you and the rex
cheers
fung

[schmiffee]

OK update...

The dogbones are the same length -and both sets look to be the original ones.

The rear shocks are around the same length (2mm difference).

An interesting sidepoint however is that "somehow" the rear of the bike (well the frame mounting point above the rear sets) have a 10mm difference - fighter being 364mm vertical whereas the standard TRX was about 354mm. What would this do??

TrxHeight.jpg

FighterHeight.jpg

Note - all tyres are the same profile (160/60/17 - Rear & 120/70/17 - Front)

[fung]

if the bones are std, with the stiffer front end . .hmmm.
have you got some shorter bones to try?
kayla has some multifit bones for a reasonable price.
maybe try the rear up some and medium hard bumping up the damping then soften the damping till its good.
what are your tyre pressures?
you might try 36/40 or 34/38 depending on the riders weight including gear.
cheers
fung

[M.V.]

Strange one...

Bearings aren't too tight are they?

Edit: Oh, they haven't mounted the shock linkage at the wrong point have they?

[schmiffee]

Strange one...

Bearings aren't too tight are they?

Edit: Oh, they haven't mounted the shock linkage at the wrong point have they?

Yeah thought that one too, but no. Have taken the top triple off a few times to check the top nut tightness, but is all good.

Shock linkages are mounted the same way and the standard TRX rides great!

Still scratching my head...

[M.V.]

Are you using a different set of triples on each bike? Different offset?

[schmiffee]

Are you using a different set of triples on each bike? Different offset?

Standard TRX is running standard triple's and forks (new springs and such)

Fighter TRX is running gold-top forks with r1 upper and lower triples with TRX stem.

The r1 forks were on the previous TRX with no problems. It is only since I have swapped them over to the fighter roject that I am having these issues with setup

[alextrx850]

any history to the fighter frame...maybe crash damaged
if so , the angle on the steering head would be less.[sharper].making the bike [sit up] at the front
most cases , the front forks would bend and take the shock...but.

[schmiffee]

Well it seems to be pretty well sorted now...no need I discuss my stupidity any further (if u know what I mean)

Maybe it was just air pressure...but don't tell anyone

[devlin]

Haha. Twas going to suggest tyre pressure and ask if you were using the same tyre. Sorted then.

[alextrx850]

Well it seems to be pretty well sorted now...no need I discuss my stupidity any further (if u know what I mean)

Maybe it was just air pressure...but don't tell anyone

Being a bit hard on yourself schmiff....glad youve got it sorted..nice looking front too

[M.V.]

Glad it wasn't something serious, like low tyre pressure