Seb from Luna Cycle contacted me to ask if the eyelet dimensions of the OEM FastAce rear shock were different than the Ohlins TTX22 replacement I changed over on my bike. I told him yes and asked why. He mentioned that a customer wants to lower their Sur Ron and Seb knew I had purchased a shorter shock then the OEM FastAce. So he figured I had experience with the measurements.

Here is a side by side comparison of my bike with the OEM 10.5″ FastAce and the 9.5″ Ohlins TTX

On the left is the OEM FastAce 10.5″ shock and on the right is my Ohlins TTX 9.5″ shock. One inch less made the ride height two inches shorter.

If I wanted to lower my bike, let’s say for a shorter person or child, I’d first look at purchasing the SuperMoto 17″ wheelset. If that was not enough I’d then purchase a shock shorter than the OEM 10.5″ model. (I want to say that I’d NEVER go with a longer shock because at 10.5″ the spring BARELY clears the swingarm linkage.) And for those suspension geniuses who think removing the shock linkage and converting it to a direct mount system is better….well OK. To each their own, but having worked with REAL suspension engineers on race bike linkage I know it’s WAY MORE than just removing something. Like progressive spring travel…? Enough said….

To bring my Ohlins 9.5 back to the 10.5 length I had a local metal fabricator make me a shock tower extender. If you want to know why I didn’t just buy a 10.5″ Ohlins TTX you can read about my reasons here.

My custom made CNC billet aluminum shock tower extension. (And sorry but he’s not interested in making these for others. I asked for another owner.)
My beloved SR now has the OEM ride height after adding back an inch of shock length. And NO by reducing the shock length the travel of the shock was not reduced….except by the travel of the rear wheel fouling on the fender due to reduced clearance and my taller profile Shinko 244s. During this time I discovered that I preferred my seat to be level, so I modified my custom seat pan to remain level rather than sloping foward.

If you change to a different shock keep in mind that the EYELETS and BUSHING at each end differ not only by brand of shock, but by the model of shock. I was fortunate that the Ohlins I purchased on eBay have the exact interior eyelet diameters of the FastAce bushings. BUT the width of the eyelet ends were more narrow on the Ohlins TTX. It required me to use additional bushings on the bottom eyelet. Since I had the top shock tower extension custom made the fabricator made it to the width of the TTX. Until I had the shock tower extension made I did have to add spacers for the top mount as well.

As you can see the bushings on each end of the used Ohlins TTX22 I purchased are different than the OEM Sur Ron FastAce bushings. But what was so fortunate is the interior diameter of the eyelets are the same as the FastAce’s measurements. I pressed out the lower Ohlins mounting shim using two sized sockets and a vice. I retained the upper bushing because it is a better pivoting bushing than on the OEM FastAce.

For information I have measured the eyelet interior and exterior dimensions for other owners:

OEM FastAce center eyelet to eyelet measurement is 10.5″
Exterior eyelet (both bottom and top) measurement in millimeters.
Exterior OEM bushing (both bottom and top) measurement in millimeters.
Interior eyelet (both bottom and top) measurement in millimeters.

So if you’re desire is the lower the ride height of your bike, I hope this information is helpful. You also may want to find out if Sur Ron sells the smaller 17″ wheel kickstand….because lowering the bike will make yours stand pretty much straight up with the stock kickstand. At least the one that comes on the 19″ wheel bike….

Lowering the fork tubes in the triple clamps is something else to do. But that’s for a whole different post, not one I plan to do either. Just keep in mind trail and angle will play a big role in changing how your bike handles….

1 Comment

  1. Mark,

    I brought this up in an earlier comment, but I did it in a different context than suspension. So I’ll give you a short version here: The questions relate to my desire to lower my forks (DNM USD-8S) by about an inch to match the 17″ rear wheel I’ll be installing. Questions: (1) do you know how far I can lower the forks in the triple trees? (2) do you know if I can have the fork travel reduced? (3) do you know any suspension shops that work on these forks?

    Thank you very much for your time.



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