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Discussion Starter · #1 ·
I've been doing a lot of reading on changing up a motorcycle. From the swingarm swap to get the rear suspension to work correctly so the I can ride the bike like it's supposed to be ridden and have it handle the way it's supposed. I really hope my shit works good and doesn't just look good but all of your guys help and my research it should.

The one thing I can't seem to find a solid answer for is ground clearance. I've seen the lowest part of the bike weather it be the swingarm or frame. But that just doesn't sound right to me. The stock ground clearance on my 05 636 is 130mm (5.11in) but even with me lowering the jack stands it's sitting on there is no way I can get it to 5in without it being stupid low to the ground. Is that measurement off of the bottom fairing or something like that? I can't get it I want to make sure where I mount my rear shock it's going to sit correctly with the sag and all that taken into account but the measurements I'm getting are making me feel stupid.
 
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Ok this is something i noticed when i first read your thread I wasn't sure where you were going with it all & as a noob i didn't want to say too much :(

What i think is happening here is that you have jacked the frame up to get the top of the shock somewhere near ?

As a base setting if you get the swingarm down to 11 to 12 degrees angle from horizontal you will be close to the angle you need there, so measure what you have & worry about the shock after !

When frame building i measure the ground clearance to the sump, around 5" is fairly standard but it does vary depending on bike & engine EG some such as bandits have a cutout one side to take the exhaust but other engines dont so obviously 5" with an exhaust passing directly beneath that would not be enough even with 4 flat side by side downpipes

Typically the exhaust will be the lowest part on an unfaired bike & that will usually be lower than my nominal 5" measurement a belly pan shouldn't add more that 1/4" at worst & you can always cut the bottom away around the exhaust if needed

Hope that all makes sense ?
 

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Discussion Starter · #4 ·
Ok that makes sense I was confused when I saw the 5in to the frame or swingarm.

Also some other good info in your post 4cups. I want the swingarm to be at a 11 or 12 degree angle? That helps a bunch. Thanks
 

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lb/hp is what it's about!
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This is why I asked for that big list of measurements when you first started asking for help with your rear suspension. Even though everyone says "just make the new shock and linkage for the bike match as close as possible to the bike it came off of" there is still a lot more to it.

On my current GSXR buildoff bike my swingarm angle after I sit on the bike will be 13.6* and my ground clearance will be 9". When you decide on a swingarm angle you also need to consider the chain run and how it changes as the suspension cycles and how that in turn affects the antisquat tendencies of the bike. There are a lot of variables that come into play if you want to get it right and in my opinion there is a big difference between it working and it working correctly.
 
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Hi guys
just to explain my previous post a little more the quoted 11 to 12 degrees for the swingarm angle is my usual base setting & what a lot of stock road bikes run at, its a safe middle of the road figure & meant as a starting point

This is usually taken with the full weight of the bike on its wheels but no rider this will obviously change as more weight is added ie when you sit on it

Obviously you wont be able to get it at exactly this without the rear shock on but you should be able to estimate it easily enough if you take into account how much sag the shock will have in it once the weight comes on

You can go up a little from this figure usually without problems, the effect is just like fitting jack up dogbones to some bikes, all it usually means is a little more weight on the front a little more ground clearance & slightly sharper turning

Another good gauge for heights & levels is that the centre of the front sprocket will be horizontal or just above the horizontal with the centre of the rear wheel spindle when viewed from the side
Too far off either way & you could be getting into the problems Geek is talking about
 
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