Dogbones - raising rear end

[mst3kguy]

don't forget you'll also need to carry around a block of wood or other device with a leather shoelace drilled through, to put your kickstand on.  after you put on the shorter dogbones, your bike will lean significantly, and that block will help.

you will also want to have handy a wood board that you can put under the centerstand when you want to get the rear tire off the ground.  with the shorter d/b's, the c/s alone won't get the tire off the ground.

hth.

[threejagsteve]

Thanks, Dean,

I already carry an old metal coaster to put under my sidestand on gravel or dirt. Maybe I'll have to look for a thicker one.

But unless I get the holes wrong, I'm figuring on barely enough clearance to lube the chain without a board under the centerstand.

Since this is just a cheap, quick and easy experiment, if I like the effect I can always go more radical later...

Cheers,
threejagsteve

[waricle]

Shouldn't be a hassle to increase the side and center stand heights so two or three inches of increase is easy.
What would be the ideal height (leaving the front standard) and raising the stands as necessary?

[andyb]

No one answer is right.


Taken from <some famous guy>'s article on suspension setup:

A common example of where riders improperly change their bikes comes when the bike steers in too slowly. Many confused riders and tuners will raise the back of the bike. This makes the nose steeper, and the bike will steer more sharply. But remember, in order to get an effect of "1" on the front of the bike, you have now make an effect of "5" on the rear. Your bike may now turn in better, but you will get less traction, more wheelspin, and more tendency to high-side. This is not what you wanted... The correct change is to lower the nose of the bike. This affects the turn in "5 (front)" and the exit "1 (rear)". Much better!!!!

Swingarm angle....tunes the way the bike reacts to acceleration. Your motorcycle wants to "squat" under acceleration due to the rearward weight transfer.

If the swingarm is too flat, the bike will squat too much, and the bike will sit back and the front will extend like a chopper. This will make the bike want to run wide or run off the edge of the track. The front end will feel light and dance about as you are leaving a turn. The result is that you have to wait to get on the throttle. You should raise the rear of the bike to correct this.

If the swingarm angle is too steep, then the bike will not squat enough, and the result will be poor traction. This is wheelspin If you can whack the gas, and the wheel spins up, then you need to lower the back of the bike.

One of these days i should post the lot of that someplace.



The other part that I think a lot of people miss is the rider.  A tall bike may be intimidating for some riders, particularly those with short inseams and/or less experience, causing the rider to feel less in control and dislike the setup.  Especially true on the street.

[mst3kguy]

andyb,

i'm a near average 5'9", but i have a shorter 29" inseam.  i've not had any mental problems (ahem!) while the bike is in motion.  it has been a problem trying to maneuver the bike now that it's taller, and even stopping when on crowned roads and such, however.  in fact, i think i did a dismount when i put my foot down in a non-existent piece of grass at a previous fj rally, that earned 9.5's from the group.

[andyb]

Dean, you're a little bastard such as myself, and as such you should save your points-earning displays of acrobatics for more important occasions.

I'm comfortable on ridiculously tall bikes (hello, 36" seat on dirtbikes/motards meets mister 29" inseam!), but I know a lot of my friends when learning to ride were quick to freeze up and freak out if they couldn't control the bike easily at a stop.  Something about being unable to control the bike easily at a standstill translated into some twitchiness when at speed, nevermind that they're different completely, it was a definite mental block.

Then again I understand many people are not quite as psychotic as I am when I ride, so power to them. 

[waricle]

Increase the rider height?
Cuban Heeled riding boots  ?

[threejagsteve]

Regarding that Progressive rear spring: I asked the seller, and he just replied that the dimensions are: ID is 61.5 mm, OD is 91.5 mm, free length is 179 mm.

Since I've never had my shock off the bike, much less apart, I'll leave it to the more experienced to advise whether it might work as a replacement spring on a '91 shock...

[the fan]

That spring will only work with the earlier bikes unless you make a sleeve/spacer to fit. the late model shock spring measures 58mm I.D. and the free legnth is appx 181mm. installed the stock late model spring is 170mm.

I found an eibach spring at lindemann engineering that measures 58mm I.D. and has a free length of 7" (177.8mm) that should work well on the late model bikes. possibly with a custom 3.2mm spacer but I can probably work around the legnth.
http://www.le-suspension.com/catalog/product_info.php?cPath=21&products_id=37

What I now need to know is what the stock spring rate. I mentioned earlier that I thought that the Traxxion Penske was specified with a 900in/lb spring (16.0kg/mm) but have also seen a post where Chris Murphy went with a 1300lb spring on his penske. I suspect that the 900 is closer to what you need, but I would really like to know what the stock spring is so that I can calculate the difference using the stock shock which is not nearly as adjustable as the Penske for adapting to different spring legnths. Anything we do will be a compromise.

[threejagsteve]

Thanks, the fan,

I was mostly just wanting to toss out the numbers on the Progressive spring in case anybody was interested - I'd figured the diameter difference meant I couldn't use it, but I'd've been happy to be wrong in that assumption.

Yes, I'd seen the Eibach spring. I have their struts on my Toyota so they were one of the first sites I checked.

And yes, it'd be interesting to know the stock spring rate. Surely that datum is around somewhere...

But for the present, my main concern is getting my forks and front brakes sorted out... and wouldn't you know it, the brake kits arrive today and the weatherman is saying the next three days are going to be the hottest yet this year!

Wishing I had an air-conditioned garage...

Cheers,
threejagsteve

[Arnie]

3Jags,

I've dug out my old notes on rear springs for the '91+ and I have some info for you.

The OEM spring is approx 700lb/in rate.  A rate of 900 to 1000 would be much better.
IMO, a rate much higher than this would not be good for general street use unless you are much fatter than I am,  @ 220lbs. 
We did have some springs made that were ~1100 lb/in as well as a bit too long and they were not very comfortable even two up.  They also overpowered the damping the OEM spring had.
Do you happen to know the spring rate of that progressive spring?

While the OEM ID is 58mm a spring with an ID of 61.5mm would be no problem as long as you put a centering lip on the spring seat.  Remember that you set preload with the ramped adjuster and if you don't have enough preload via the adjustment, you can add some additional with a thicker seat.  This is NOT a critical spec, but you do need to get your preload correct.

Cheeers,
Arnie

[threejagsteve]

Thanks, Arnie!

Valuable information and good to know!

Yes, 900 lbs/in. is probably about right. I wouldn't be close to 220 even soaking wet with a case of beer under each arm. And I don't want to go so extreme that the bike is miserable around town.

Cheers,
threejagsteve

[TRoy]

Basic no frills Penske Sport from Traxxion Dynamics, $625: http://traxxion.com/detail-57.aspx

Old linky no worky heres the new one  http://traxxionstore.com/detail-57.aspx

That is all 

[Dan Filetti]

Basic no frills Penske Sport from Traxxion Dynamics, $625: http://traxxion.com/detail-57.aspx

Old linky no worky heres the new one  http://traxxionstore.com/detail-57.aspx

That is all 

That's the same link!

[rktmanfj]

Basic no frills Penske Sport from Traxxion Dynamics, $625: http://traxxion.com/detail-57.aspx

Old linky no worky heres the new one  http://traxxionstore.com/detail-57.aspx

That is all 

That's the same link!

Read them again...     

Randy T
Indy