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Discussion Starter #1
I've got my finger on the trigger to order some shocks for my GT. I've read everything in the archives. I don't want to lower the bike, I would rather raise it to improve cornering clearance on bumpy roads. I can raise the front end by at least 5mm by lowering the forks.

The stock shock is 380mm, and I'm thinking about getting 390mm - any thoughts?

What are your recommendations for shock length?
 

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When I ordered mine, I went +10 and and then raised it another 10mm and like the additional clearance it gives.

Most after market shocks will give you a ride height adjustment, so if you order 390mm, you should be able to get to 400mm if you want to.
 

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You've got longer legs than I.


Okay, almost everyone does.


Keep in mind that raising the whole bike evenly will keep the rake the same, but you will still gain trail, which slows steering, so you may not want to raise the front as much as you rasie the rear. (course, you can't raise the front much more then 10 mm without going to different forks, but my 900SS forks would allow probably 40 mm more in the front).
 

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Discussion Starter #4
Keep in mind that raising the whole bike evenly will keep the rake the same, but you will still gain trail, which slows steering, so you may not want to raise the front as much as you rasie the rear. (course, you can't raise the front much more then 10 mm without going to different forks, but my 900SS forks would allow probably 40 mm more in the front).
I don't see how raising the bike evenly will affect trail. There is no change in rake, no change in wheel diameter... what am I missing?
 

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I don't see how raising the bike evenly will affect trail. There is no change in rake, no change in wheel diameter... what am I missing?
Actually, now that I think about it, it can change OR stay the same. It depends on whether or not the triple clamps have any rake. If the triple clamps hold the fork tubes parallel to the steering stem, then, you're right, the trail will not change. I don't know if our bikes have any rake set into the fork triple clamps or not. Some bikes do, some don't.

Hmm. More research needed.
 

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Raising only the front will increase the trail since the fork tubes are angled forward. Raising only the rear actually reduces trail since your swingarm is actually rotating downward and forward as you raise the rear. In both cases the trail is only nominally effected.

If your rake is x, and you lower the fork tubes in the trippes by y, then the trail extends by z.

x; y; z
20deg; 10mm; 3.4mm
20deg; 20mm; 6.8mm
22deg; 10mm; 3.7mm
22deg; 20mm; 7.5mm
25deg; 10mm; 4.2mm
25deg; 20mm; 8.4mm

As you can see, the increase in trail is pretty darn small. If you calculate the rear, you'd take into account the swing radius of the swingarm, the increase in length of the rear shock, and how much the angle of the swingarm and rear shock change with respect to each other as the raise is made. Think about adding 12 inches to the rear, the swingarm would actually be close to vertical. That same thing happens when you raise 10mm, but on a much smaller scale. The trail changes by much less on the rear than the front for an equivalent raise.
 

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You're right that the change is small in length, but they say that an expert can detect a change of 1 mm in trail, so 3 - 4 mm might not sound like much, but a normal rider should certainly be able to notice it.
 
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