I've seen posts on upgrades to 12" or even 13" rear shocks but nothing about the safe compressed length. Too much stroke or compression to the bump stop and the belt guard will hit the frame then possibly the tire will scrub the fender and wiring underneath. Has anyone actually measured the minimum safe distance between mounting holes on an otherwise stock Iron? I estimate it around 9" but need to remove the shocks and jack up the free swingarm + wheel to confirm.

 

OK, not the hot topic of the week, but I checked the numbers are here they are. The minimum compressed shock length for a stock XL883N should be 9 5/16" = 237mm. Any shorter and the belt guard impacts the frame and rear reflector (see X in attached pictures). Even with the belt guard removed, the belt just scrapes the upper drive pulley cover. Why care? Well, if you want to have a wide choice of aftermarket shocks it's best to know what extended and fully compressed (on the bump stop) lengths will work. Most work with fully extended shocks in the 11 ~ 13" range but I couldn't find any reference to the safe compressed length so post my findings here.

Cheers, RR

 

Are you asking if a longer shock would increase the chance of contact with the inside rear fender versus a shorter shock?

I would doubt it, I think it would impove clearance. Plus, a longer shock won't physically compress as far.

My 1991 has 13.5" shocks, stock. And there's a lot of tire/fender clearance compared to the newer lower bikes. For cornering, I guess taller shocks are better too, better lean angle.

John

 

Nope - longer shocks than stock raise (no pun intended) different potential issues like the rear axle bolt hitting the muffler or steep lean angle on kick stand.

Longer shocks have room to compress more by design - this is their advantage as you work with more compression stroke for a better ride quality.

By the numbers above, a stock 11" shock has only 1 11/16" stroke before using up safe compression to the bump stop, so no wonder their ride quality is poor. A 12" is an improvement allowing an additional 1" of stroke for 2 11/16" total, if designed that way.

The stock tire still cleared the fender in my measurements but a taller / fatter tire would be a problem.

As you say, the newer lower bikes like my Iron don't allow as much room to play around with rear shock dimensions, hence my measurements.

Cheers, RR