TOPIC:

solomrus wrote:

hmm, that'd probably be why i had never heard of them before.

fossil, are you measuring from the ground to the top or bottom clamp? or are you measuring the free length of the fork tubes?

also, do you have an angle gauge to measure your head stock with?

--r

The 28.5" is from the top of the fork to the middle of the axle - the actual length of the fork, not the "height".
Wish I did have an angle gauge so I could give an accurate measurement.
I'm basing my calculations on the 1" equals 1 degree rule of thumb - not dead accurate but in the ball park. Approx. 2" higher in the rear, 3" drop up front gives about a 5 degree decrease in rake, but the triple clamps have less offset so the trail isn't as radically altered.
Buells have a radical 21 degrees of rake and 84mm of trail - just something to think about - some of the old "rules" don't seem to apply anymore!

Post edited by: Fossil, at: 2007/04/27 17:14

with the weight of the bike on the suspension, or at full droop?

just trying to get a handle on what you are looking at, so i can be on the same page when i start tweeking things a bit. 8^)

that is something else that i observed. my trail figure isn't awful, even with the excessively narrow rake number.

more rake and the trail number will come down some.

if the clamps don't give me much up front, then i will bring the rear down an inch at a time, and see how the numbers change. i'd feel more comfortable with 23-26 degrees of rake vs. the 19 i have now.

thanks for all the pointers man. i totally appreciate it.

the collective experience here is amazing. always astounds me.

--r

solomrus wrote:

with the weight of the bike on the suspension, or at full droop?

just trying to get a handle on what you are looking at, so i can be on the same page when i start tweeking things a bit. 8^)

that is something else that i observed. my trail figure isn't awful, even with the excessively narrow rake number.

more rake and the trail number will come down some.

if the clamps don't give me much up front, then i will bring the rear down an inch at a time, and see how the numbers change. i'd feel more comfortable with 23-26 degrees of rake vs. the 19 i have now.



thanks for all the pointers man. i totally appreciate it.

the collective experience here is amazing. always astounds me.

--r

The measurement was taken with just the weight of the bike, not on full droop.
The trail isn't so bad because of the reduced offset in the triple clamps.
I think you'll be able to dial it in by adjusting your rear ride height.
I know what you mean, the collective information here is terrific - has helped me a lot.

picked up the z1000 top clamp saturday morning.

it got me back 2 degrees of rake, with no other change. raised the front quite a bit.

still quite an angle to the bike tho.

i'm looking at possibly altering the rear geometry some to get another degree or two.

it's at 21 now, static height, picks up another degree with my weight on it. 22, if i use your rule of thumb fossil, i can probably pick up another degree or two by dropping 1-2 inches out back.

i REALLY want to ride it before doing that, just to see if the 58" wheelbase helps with the stability.

will know more this coming weekend, if the new bars show.

--r

I picked up a cheapo angle finder and measured my front end. It's sitting at 25 degrees with no weight on it with the specs/measurements I mentioned a few posts back.

you rock man!

i took the same measurements that you mentioned.

my forks are 28.5" from the center of the axle to the top of the cap(not the top of the adjuster, the top of the actual cap) and my shock mounts are 29" from the ground when the bike is straight up.

i'm at 21 degrees.

hmm. buells are that steep? they also have those uber short wheelbases too...

--r

Russ,
Is your bike really that steep??? That's almost unreal. I wonder what your stability is going to be like.
I have some Buell experience, the XB series does have a 21 degree rake, and (most have) a 52 inch wheel base. They are the most composed streetbike that I have ever had on a track (not 'track' or 'race' bike, but 'street' bike). But look at their frames, they are insanely beefy. With the 'Lightning' ["S model])version of the XB (the nekked version of the ["R model"] 'Firebolt') the bike offers a lot of leverage at the bars b/c of rider position and wide bars. Well, you don't need a ton of leverage with a 21 degree rake and a 52 inch wheelbase. I've had a couple different examples of those things shake there heads on me at 100+ speeds in a corner. Never got out of hand...but sure didn't inspire any confidence. The 'R' model Firebolts never get out of shape, so I thinks it's probably in the added leverage and re-distribution of rider weight that causes the 'wallow'. (I think that most of their riders won't find that edge, so the point is moot).
Also another factor with the XBs is that they run a perimter brake, which is like adding mass to the outter portion of the rim. Buell is quiet about it, but this effectively slows steering by adding reciprocating mass to the wheel; placing the weight at the point furthest from the center of the point of rotation. 'Different'...that's for sure.
Didn't mean to 'thread jack'...back to your steed Russ...where are you at, now?
-KR

Post edited by: Bad Kaw, at: 2007/05/03 11:02

so, hmm. tiny wheelbase, acute steering head angles, and lots of rotating inertia.

it's a gyro on the end of two pencils. they keep the engine mass down low as well, i think, and that helps with the COG and how flick-able the bike is. interesting school of thought behind them.

where am I at?

i'm waiting for the UPS truck that has my black renthal fat bars(mini bend) and TAG kawasaki rubber mount bar risers for an 1 1/8ths inch bar.

those will mate up to my z1000 top clamp, and with a little work this coming weekend, might net me the first ride. 8^)

58" wheelbase, 22 degrees of rake, and 4+ inches of trail. it'll be a very calm ride, i am thinking.

--r

Cool. Man that thing is just flat out stimulating.
...when they take your license, can I have it?

you can't have my license if they take it...

OH!!

you mean the bike...

8^)

hey, check the email i sent back to ya. we're planning on coming down. i won't be riding the bike down, but we'll be there. i'll bring a lid in case we go do some test rides. 8^)

--r

solomrus, haven't seen anything posted for a while, was wondering how your project's coming along. What did you end up doing about your geometry? Got pics?

i'm around. 8^)

we had this huge ride to california planned, and we had to rebuild my son's 78 kz650 c2...

long story short: we built the 650 into a kick ass 700, made it to estes park colorado where he ran into the rear of my zrx, spend all our trip money repairing our bikes, then came home.

i've got a bunch of work to catch up on in the shop, but then i am working on MY Bike for a while.

i will ride it yet this year.

-r