How much clearance?

[gpreciado]

Hi Gang,

I was reading sxecafe's CB550 build and someone brought up that he may have an issue with the back tire contacting the rear seat hoop he built, so this brings me to my question. How much clearance is good? also is it measured with rider or without. thanks guys. Or is this just bike specific?

 

[Swapmeet Louie]

Bike specific, rider size/weight etc.

 

[lockard666]

if you can see it & get an accurate measurement, measure the travel on the shock shaft... if not, measure the length of the coil itself(not eye to eye, just the coil)... then, measure the thickness of a single coil & multiply that times the total number of wraps the coil makes... the difference of those two numbers is how much the spring can compress... since shocks are angled slightly and they are forward of center(of the wheel), travel will be slightly more than total compression... i'm sure an engineer could figure out exactly how much more with a calculator, but i'd draw it out on cardboard from there & maybe use a yardstick as a mock swingarm.

 

[gpreciado]

sorry forgot the bike is a 76 xs750, I am 5'-8" and i am a whopping 178.thanks guys

 

[hillsy]

It is bike specific - shock length, swingarm length, hoop position, etc.


Basically, if you can remove your shock springs, then mount the dampers on the bike, and if you move the swingarm up as far as it will go and there is still clearance, then you are sure to be OK.

 

[crazypj]

It's generally accepted that 1/2" is minimum clearance on full compression.
You need some clearance because tyre 'grows' with centrifugal force when it's turning.
Best way to do it is remove springs and fit fully compressed damper but it's possible to measure the 'gaps' between coils and make a bar to bolt in and check clearance (e.g. if you have 6 spaces 10mm = 60mm. If shock is 300mm center to center extended, -60=240mm to center of mounting hole)
You need a vernier to measure as you have to find smallest point between coils (although, even rough measurement is better than tyre 'grabbing' something solid when your riding)

 

[gpreciado]

perfect, i should be perfect i have about 2-3" at full compression. I think these shocks may have been changed before i got them.thanks alot guys.