Gabelschaftrohr Einbauposition (SMC 2010)

    Grüß euch,

    hab eine Frage an euch, da ich gerade meine SMC neu aufbaue.
    Kurz die Daten:
    KTM SMC 690 Bj 2010

    26.000km


    Thema:

    Das Gabelschaftrohr hat bei mir oben einen Punkt, an der Unterseite eine Ausfräsung wodurch ich das Gabelschaftrohr nur in zwei Positionen in die untere Gabelbrücke einsetzen kann.

    Da die Wellenmittelpunkte (für Brückenklemmung) extrentrisch zu den Lagermittelpunkten sind, habe ich herausgefunden, dass dadurch die Gabelbrücken 2mm vor oder hinter den Lagermittelpunkten liegen.


    Beim Ausbau des Gabelschaftrohres war der Punkt vorne, sprich die Wellenmittelpunkte für die Klemmung der Gabelbrücken waren 'vor' den Lagermittelpunkten.

    Nun zur Frage:

    Welche Wirkung/einfluss hat die Einbauposition auf das Motorrad bzw das Fahrverhalten?

    Wird je nach Einbauposition der Radstand verlängert/verkürzt? (Ich glaubs nicht, da man ja hintn schon mit dem Hinterreifen und der Kette den Radstand verändern kann)

    Hat das irgendwas mit dem Nachlauf zu tun?


    LG Rene

    My apologies for answering in English.




    34 brings more "nimbleness".

    32 brings more "stability".

    From the factory they come on 34 mm offset.
    Caster is fix but you can modify the offset, that changes the trail (distance on the ground from center of the wheel to the projected line of the steering axle).
    It moves the front end (forks + wheel) further or closer from you, this indeed changes the wheel base but this is not the main goal here, it's more like a side effect.



    For example:

    I personnaly like the 34 (from the SMC) MORE than the 35 from the R (I've had the R / PowerParts triples for a long long time but I don't really like them, everytime I jump on an SMC I prefer it, I'm gonna look at replacing mine (+ I hate the anodized orange).
    I find it to be better even in slow curves, hairpins when you throw the bike from side to side quickly.
    Gives much more feedback + grip so you end passing faster than with the "quicker steering" set-up so it counterbalances it.
    There's a lot of psychology and feeling involved in geometry changes. :lol:
    Sometimes you gotta make a counter intuitive change to bring back confidence and feedback.

    Anyway I encourage you to try it out for yourself, only a few people have tested the 32mm offset.
    But try to make 1 change at a time, if you replace the tires + service the forks + change the offset + change the height of the forks in the triple clamps + change preload in the rear at the same time it becomes pointless. :(

    BACK IN THE DAYS --->https://www.supermotojunkie.co…set-on-the-690-smc.70063/


    Here's an animated picture of the change in triple clamps offset.

    chassi11.gif






    This comes from the powerparts' triple clamps manual, it's the EXACT same shit as the 2012 + SMC R triples (also same system for previous generations) but it was never explained in the manuals as far as I'm aware. Shame.




    sans_t39.png

    5 Mal editiert, zuletzt von Thor_du ()

    So first of all i want to thank you for your answer, although it is written in english :lol:

    It's really a shame that KTM didn't put that information in the workshop manual, as it is an important feature to mention regarding vehicle dynamics.:crazy:

    To get back to the topic, as i am currently doing a bikebuild my aim is to assembly the bike just once :kapituliere:
    From memory i can say that i was always satisfied with my bike but in turns it seems to be like i have to force it into the turn or better say put effort in it. Since my last ride was almost a year ago, i cannot really

    say if there is much improvement.. I also did a suspension service (also tuned it for my 'weight') and also got new tires, so it will become 'pointless' as you say :D

    But i am looking forward to get a 'better' bike with the change of the offset to 32mm..

    The only thing i do not fully understand is mentioned in the stated forum [1]: So I then swapped the offset. Well, it's a big difference and IMO a big improvement in handling. The bike still will instantly drop into any turn but it is now more stable at higher speeds. The biggest difference is that the weight seems to be much more rear biased now and the front still seems secure.


    If i change the offset to 32mm it becomes more agile in tight turns and less stable at high speeds, right?
    I also get better feedback in comparison to the 34mm option?

    so to state the issue from my point of view:
    Offset 34mm (factory setup): Better handling in long curves, more stable at higher speeds - Main goal is overall stability

    Offset 32: Better handling in tight curves, less stable at higher speeds - main goal is handling
    Am i thinking the right way?


    [1] https://www.supermotojunkie.co…set-on-the-690-smc.70063/

  • Siciliano

    Hat das Label 690 SMC hinzugefügt.

  • Siciliano

    Hat den Titel des Themas von „KTM SMC 690 - Gabelschaftrohr Einbauposition“ zu „Gabelschaftrohr Einbauposition (SMC 2010)“ geändert.

    It is really is a shame + I'm almost sure it's not even mentionned in the owner's manual. :(

    For the rest I'm sorry looks like my long speech + my experience got you confused! It's the exact opposite.

    "If i change the offset to 32mm it becomes more agile in tight turns and less stable at high speeds, right?
    I also get better feedback in comparison to the 34mm option?"

    If you change to 32 mm offset you'll have more stability everywhere.
    You'll not necessarily notice the lack of flickability / turnability (if that's a word), this is my opinion backed by my experience with this + what the guy on SupermotoJunkie said:

    "The bike still will instantly drop into any turn..."

    And, again, that's what I've noticed when going from my 2011 SMC with R/PP triple clamps (set on 35 mm offset) to another SMC with OEM triple clamps set on 34 mm offset.
    Btw both bikes are springed in the back for a heavy guy (I'm around 112/113 kg in gear as is my friend) and both have the same job done in the forks, same oil, same simmerings, both chassis are greased once per year etc, so they are very very close.
    With another SMC springed for a 80kg guy I wouldn't have said that because the bike would have been completely collapsed at the rear with my weight therefore changing the geometry dramatically.
    Comparison would have been useless.


    "Offset 34mm (factory setup): Less stable everywhere / a bit more flickable

    Offset 32mm (alternative) : More stable everywhere / a bit less flickable

    Take a look at the gif, when it switches to the smaller offset (at the top, in the triples) it gives a bigger trail number on the ground --> Imagine a Harley or a sand bike! :D
    When it switches to the bigger offset, it gives a smaller trail number on the ground --> Imagine a sportsbike or trakc oriented supermoto.

    This is pure theory though, as I've said just before passing from 35 to 34 I didn't notice the lack of flickability or anykind of lazyness in the steering inputs, bike felt more planted everywhere.
    So in the end I was faster everywhere but more relaxed at the same time, even in very slow and tight stuff, I live between the Jura and the Alps.


    I have never tested 32 mm on a 690 SMC set-up properly for my weight.

    PS: I find the explanation a bit confusing both in French and English, maybe they are better in German?
    By "fast race courses" they mean "high speeds" like a gp track, not a go kart track.

    5 Mal editiert, zuletzt von Thor_du ()

    "From memory i can say that i was always satisfied with my bike but in turns it seems to be like i have to force it into the turn or better say put effort in it"

    Did the guys at the suspension shop end up putting a stronger spring in the back or softer springs in the front by any chance?
    Or was it just hydraulics change?

    How much do you weigh?

    Einmal editiert, zuletzt von Thor_du ()

    Hi, sry for the late reply but yesterday i just read your message on my phone and it was a bit much to process :D


    OFFSET TOPIC:

    So i just searched for my old steering shaft and the marking was in the back, therefore the offset was 34mm, correct? (sry i am a little bit confused currently :D)
    This means that the trail was smaller and i had more stability and less flickability (more stable at higher speeds?)

    And if i am using the 32mm offset, which means i have to rotate by 180°, then i get a bigger trail.
    This means that i now have less stability and a little bit more flickability?


    I only want to take tight curves better, thats the aim for me :D Then i need the 32mm option?


    EDIT: From what i read in your message, the 34mm offset is already the 'better' option for tight curves/better flickability?


    SUSPENSION TOPIC:
    No everthing remained the same regarding springs and so on. They just made a hydraulics change more or less.
    I also told them my weight so i guess they also matched the suspension a bit for my weight.
    i weigh 82kg and nearly 100kg with full gear on.



    Just a short offtopic question:
    English:
    I got a Steering head rep kit and additionally to the bearings, the bearing shells and so on there are two O-rings..
    The first one is 25x3.55mm and the other one is 28x2.55mm. Using the Onlineshop of a dealer i can't find any of these o-rings in the assembly drawings, searching in other model years resulted in finding one o-ring between the upper triple clamp and the sheet metal cover, see figure.
    But where does the other O-ring (28x2.55mm) belong?

    German:
    Hab ein Steuerkopf Rep.Kit gekauft und im Set waren neben den Lagern, Lagerschalen usw. auch zwei O-ringe mit den Maßen 25x3.55mm und 28x2.55mm enthalten.
    Bei der suche im sparepartsfinder habe ich in meinem modelljahr die O-ringe in der Zusammenbauzeichnung nicht finden können, erst bei neueren Modelljahren war ein O-ring (25x3.55mm) eingezeichnet, siehe Bild. Dieser befindet sich zwischen oberer Gabelbrücke und der Blechabdeckung. Wo gehört also der zweite O-ring (28x2.55mm) hin?

    pasted-from-clipboard.png

    Einmal editiert, zuletzt von R3n3 ()

    Sorry there was an error in my text, 1st part was correct, 2nd part (bold text) was wrong I must have been more tired than I thought. 3rd part was correct though... Voilà.

    Let's fix this once and for all (my fault) :lautlach:

    Offset 34mm (factory setup): a bit less stable everywhere / a bit more flickable

    Offset 32mm (alternative) : a bit more stable everywhere / a bit less flickable
    Geometry and suspension changes are always a trade-off.




    Conclusion:

    If I were you I would stick to 34 mm, get used to your new suspension + tires and start to play with your fork's height in the triple clamps.
    Especially because you've said: "in turns it seems to be like i have to force it into the turn or better say put effort in it"

    To counteract that you can lower the front of the bike by sliding your fork legs up in the triple clamps.
    Go in steps of 2 or 3 mm. ;)
    At each step the force you have to put in the handlebars to put it down + keep it down will decrease.
    If the bike starts to go down very sudenly or "falls on its own", then go the other way, either a full step or half a step.
    If you change brands or models of tires you'll have to do that once again, re find that sweet spot.
    Same thing if you increase preload in the back.



    It's been a long time since the last time I've had an SMC's steering head in my hands but yes I believe if it's at the back then it's 34mm, if you haven't messed with previously / are the first owner or if you are 100% sure about the service history then yes it's the factory set-up with the marking at the back.

    For your O-ring problem, did you get this kit? ---> 00050000930

    This kit goes on many many bikes so it's possible that some of these parts are only for EXCs or other bikes for exemple.

    Side note, the official spareparts finder doesn't show THAT O-ring you've mentionned (on your printscreen).
    It only shows on SMC R 2012 + partsfinder.

    Are you sure there's a recess under the upper triple clamps to host this O-ring?

    Both bikes share the same repair kit btw ---> 00050000930 (again)

    SMC (2008 to 2011)

    pasted-from-clipboard.png

    SMC R 2012 +++

    pasted-from-clipboard.png

    I am really thankful that you support me with this issue! So thanks a lot :prost:

    To conclude:
    I will stick to the 34mm since i want more flickability! So thatoption was already used before my spontaneous bike disassembly :kapituliere:
    So that i get i finally: 34mm offset -> less trail, more flickability and less stability; 32mm offset -> more trail, more stability and less flickability

    Thanks for the suspension setup tips, i will consider this after i reassembled my bike :D


    Unfortunately, i am not the first but the third owner and there is no service history.. But that's the main reason for the disassembly, engine is in germany at Pirate Racing for a revision and the remaining bike i build up by myself :D


    Zitat von Thor_du



    For your O-ring problem, did you get this kit? ---> 00050000930

    Yes, this one.
    But during the disassembly, the upper O-ring was on the shaft, but in the spareparts it's not mentioned (But model years 12 and up have it ) :D
    So i guess i will just renew the upper o-ring.

    Don't hesitate to test things, with fork height, clickers etc if you know were you've started and don't like a setting then just go back to the previous setting. :)

    Do not overtighten the lower triple clamp + axle bolts.
    This is one of the most critical part + make sure you get the fork's alignment right.

    I encourage you to watch these 2 videos:

    1) https://youtu.be/_B4zb2dfijw

    2) https://youtu.be/DYHV78tWs1c

    Nota:
    On our bikes the "captive" fork leg is the left side (with the 27mm nut), not the right side like on this RSV4 but it's the same principle, just the other way around. ;)
    Refer to this video for installing wheel / fork legs and brake caliper because just like on our bikes it has a radial foot and brake caliper.

    I hope I've helped you in some way. :Daumen hoch: