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Buell Forum » 1125R Superbike Board » Archives 001 » Archive through May 29, 2009 » Lowered my front end. « Previous Next »

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Parrick
Posted on Tuesday, May 26, 2009 - 09:16 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

The bike just didn't seem to roll naturally into the turns even at moderate speeds. I had the rear preload maxed out and the front preload down to 2 turns up from minimum and still not quite right. Last night I raised the fork tubes by 7mm and now she feels about right.

The only thing that bothers me is that I had to remove those pesky fork-tube-height-limiting C-clips to drop the front end and I'm wondering if there is any real viable reason for them to be there. So far I can't seem to find any negatives to this adjustment. The rear end doesn't seem a whole lot lighter than normal under heavy braking. No wobbles up to 120mph and I pulled a moderate stoppie to compress the front end. No mechanical interference evident.

Anyone else lower the front end?
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Jersey_thunder
Posted on Tuesday, May 26, 2009 - 09:25 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

thats odd...our piliot says it's the"BEST" turning machine he ever road...keep us in formed how it does on the track!!!
ummm?

JT

(Message edited by JERSEY_THUNDER on May 26, 2009)
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1_mike
Posted on Tuesday, May 26, 2009 - 09:51 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

The snap rings are for quick placement during assembly (accuracy), and for anyone reassembling their front end and safety (no slippage of the clamp fasteners aren't tight).

Mike
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Ccryder
Posted on Tuesday, May 26, 2009 - 12:38 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Hmm, sounds like something wasn't set correctly to start with. Mine drops into turns just by me thinking (and maybe a touch on the bar) and is ROCK STEADY. Changing directions is just as easy.

Anytime you change the height of the forks relative to the front end, geometry will change and most likely, not to the best overall.

Just my $0.02 and YRMV.

Later
Neil S.
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Slaughter
Posted on Tuesday, May 26, 2009 - 12:50 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I'm kinda wondering what tires/pressures and what your suspension settings are front and rear.
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Parrick
Posted on Tuesday, May 26, 2009 - 04:48 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Tires & pressures are stock. Front preload is now at 3 turns out from min. Rear preload is now at 2 clicks down from max. Front compression is 1/4 turn out. Front rebound is 1 1/2 turn out. Rear comp is 14 clicks out. Rear rebound is 1 1/4 turn out. I'm 6ft. 215 lbs.
Yes the front end is tight on the compression setting. I always start that way and then back it off after I get everything else lined up. I think I'm a little soft on the rear comp. I'll probably tweak that next.

-Pat
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1_mike
Posted on Tuesday, May 26, 2009 - 05:14 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Sounds like you may want to check the "sag" of the suspension.

One thing I've found to be somewhat helpful, is to verify the both the front and rear drop about the same when putting your full weight on the suspension, hands on the bars.
Someone to help you is a good thing, once you've done it a few times, you kinda learn the feel and can come close by yourself...but it takes practice.

If the rear is set too soft (spring or compression) the front will feel overall, too stiff.

Mike
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Imonabuss
Posted on Tuesday, May 26, 2009 - 11:07 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Parrick,

Be very, very careful. When you slide the forks up further, the tire could bottom into the exhaust system under hard braking. That's what clips are for on most bikes. I made this mistake on a Yamaha one time, and holy shit you can't imagine what happens when the front tire bottoms into the bike and the wheel locks.
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Parrick
Posted on Wednesday, May 27, 2009 - 10:39 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I agree this needs to be done with care. I did a lot of measuring to come up with the 7mm figure. So far it all looks to have ample clearance but I won't be sold until I figure out what the absolute unsprung full compressed fork length is. Shop manual got here today so hopefully its not too involved to release the fork spring and check full travel.

Bike rides really well now. I wanted to get it to this point and still have a little adjustability on either end. For me this is about perfect for street riding. I took the rear compression to 8 clicks with 1 1/2 turn out on rebound. Feels very balanced and nimble. Once I'm convinced that the basic geometry is where I want it I'll relax the compressions a bit. I always like to "get to know" a new sportbike with the suspension very stiff.
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Court
Posted on Wednesday, May 27, 2009 - 12:42 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

>>>Be very, very careful.

Actually . . . you MAY want to be even more careful than that.

These types of changes, particularly to a bike with fairly "aggressive" geometry not only pretty well place you at some risk (with your insurance) in the event of an accident but can manifest some unexpected tendencies with little or no warning.

I am not qualified to say "don't do it" but I do have the experience to say USE GREAT CAUTION and realize that you are becoming a self proclaimed test rider.
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Ccryder
Posted on Wednesday, May 27, 2009 - 06:32 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Court, how many times have we had this discussion? I guess this one is different since the intention is not to just lower the seat height.

Oh well, the same scenario can happen.

Time2Ride
(Long verse of "Riders Of the STORM", for today's ride home!!)
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Parrick
Posted on Wednesday, May 27, 2009 - 09:00 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Okay, what's the "SCENARIO"?
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Khill
Posted on Wednesday, May 27, 2009 - 09:48 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Just my .02.....

For the track riding I have done, if anything, I would want to raise the front end. Having sampled a bunch of these bikes, we have set on a pretty "go to" setting that works really well, some fine tuning, but not much. And again, we used these for track use only....

Front:

PL-stock
Comp 3/4-1 turn out from max
Reb 3/4 turn out from max

Rear:

PL- #7 of 9
Reb- 1-3/4-2 from max
Comp 5 clicks from max
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Ccryder
Posted on Wednesday, May 27, 2009 - 10:47 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

The scenario can vary drastically (none of them too good) depending on a number of factors.
1) How you ride
2) How you have the rest of the suspension set up
3) Road surfaces
4) Tires

and a few more that don't come to mind right now.

Bottom line is Buell set out to make the 1125 one of the best handling bikes on the street and it required many iterations until they got it right. Buell had at it's disposal some of the most experienced riders and designers in the industry (including their namesake). Granted they had to make some compromises but they also had to make it safe for riders from 140-280 lbs (or more).

SO if in your vast experience you feel that you have to make such a change to get the bike to handle "properly" (after using up all the other combinations of adjustments available) then go ahead but, it's your butt (and other body parts) that you are risking.

Well I'll stop now and leave you up to your own decisions and hopefully, nothing bad will happen. We are just trying to caution you about the dangerous direction you may be heading.
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Fresnobuell
Posted on Wednesday, May 27, 2009 - 10:48 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Ken, doesn't weigh have a significant impact on suspension settings? I have noticed that magazines often like to publish recommended settings, but never do they publish a weight.
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Khill
Posted on Wednesday, May 27, 2009 - 11:11 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Posted on Wednesday, May 27, 2009 - 10:48 pm:

-------------------------------------------------- ------------------------------
Ken, doesn't weigh have a significant impact on suspension settings? I have noticed that magazines often like to publish recommended settings, but never do they publish a weight.

Sure, as does riding style to a degree. But, Nick and I use the same suspension settings even though he weighs 45lbs less than me....
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Parrick
Posted on Thursday, May 28, 2009 - 09:45 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Thanks Khill,

I appreciate you posting some numbers. That sort of input is helpful. I should point out that I got this bike as a recreational street bike rather than for track use. The settings I'm working with are more to my preference in that regard. I like tight handling in the curves but you are rarely going to find me pushing the speed limit too much on the straights. Granted, it's hard to judge based on paper values but I think I see some parallels. By lowering the front end I have decreased the fork rake but I like the front end set pretty hard on the compression. Steering responsiveness, limited fork dive and less stand-up on braking are what I look for in a turn. Your settings are softer in the front end but pretty stiff in the rear. In a turn your front end is going to compress and result in a similar fork angle through the turn. (I'm guessing you maybe weigh a bit less that me too?) Coming out of the turn on the straights your front end is going to stand back up resulting in greater fork rake and better high speed stability. For track speeds that's what you want. (Although for a bike with no steering damper I'l be darned if I can induce a high speed wobble in this thing. Kudos Buell!) For me, at normal straightaway road speeds I still like the increased responsiveness of increased rake for things like flipping around potholes and suicidal possums.
It's just a preference based on application and a developing preference at that. I tossed it out there for feedback and to see what others are doing with suspension. I do have a little background in 2 wheel geometry but I'm not trying to claim "Vast Experience" (Sarcasm noted, Cc)
Perhaps we should all put our solenoids back on and ride the bike like it was intended to be.

-Pat
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Smilesracing
Posted on Thursday, May 28, 2009 - 10:36 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Just to make things interesting... I have lowered the forks on my race bike by 10mm. I have Traxxion Dynamics 20mm fork kit. And have no ill results. 400lb+ race bikes need alot of muscle to turn "at speed". This helps dramatically reduce turn in effort. For the street? prolly not so much. But everyone is different.
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Ccryder
Posted on Thursday, May 28, 2009 - 11:05 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Pat:
Keep up the good work. Hope it works out for you. I don't know why but the issues that you are trying to "cure", I don't have with my 1125rt.

After a 16 hour day, it's time for sleep.

Neil S.
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Madduck
Posted on Friday, May 29, 2009 - 02:05 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

I have 20 years of bike suspension setup on only three dirt tracks; Peoria TT, Sppringfield and DuQuoin miles. For identical sized riders you always end up with different suspension setups for best times. There may be a generic setup that will get good riders into the finals but there is not one that will get you on the podium. Riders attitude and "comfort" level dictate how that individual will actually go fast. I've seen a rider pickup a half second a lap just because his tuner said he put Nitrogen in the tires. If you are going faster, you did something right. If you feel better you may not have done anything. Always measure something, seat of your pants tuning don't win nothin. Find someone about your size, riding your type of bike and who is going faster. Listen to em. Never listen to people who aren't racin or who are going slower.
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