I have recently been configuring an Ohlins rear shock to my bike. It’s the TTX22 9.5×3.0 model. What I have discovered is since the length of the OEM FastAce shock is 10.5 inches the loss of one inch can come into play. The rear ride height is obviously less which in turn increases the trail of the front. By how much I have not measured. How much does it affect the handling? For me it is no slower in steering or more stable downhill. I will say that they feel of the rear shock is just as amazing as it was when I changed from the RST forks to the Dorado’s. It’s plush. I had to do some calculations to see just how losing approximately 1″ of travel affects the bike:

I fabricated this measuring tool to see how much travel occurs in each shock before complete compression occurs where the rear tire hits the seat fender. Keep in mind that I am using Shinko 244s which are about one inch taller in profile than the OEM knobbies. The line marked “Fast Ace” s where the fully extended OEM shock reaches. The line to the left of that is the Ohlins fully extended. The line furthest to the left is where the measuring tool reaches when the bike is fully compressed.
Here my homemade tool is installed in place of a shock for measurement.
The OEM 10.5 inch shock yields 3″ of stroke before the tire impacts the fender. The Ohlins reaches 2.25″ of stroke.
The linkage, bushings and nylon shims. I recommend that these be inspected and regreased about every 1k miles depending on your conditions.
I’m 180lbs in gear and took the bike over bumps and small jumps. As you can see I still have at least an inch of travel left before hitting the bottom out bumper. One other issue is the 10.5 inch OEM shock gets VERY close to the linkage on full extension. As the shock compresses it moves AWAY from the linkage.
This is where I do most of my testing. I did NOT go off the larger jumps for testing!
I’m running the 502 lbs pound spring and have set my preload to 25% of total travel.
The manual scissor lift in the foreground allows me to adjust the bike to whatever height I wish in small increments. Perfect for measuring just where tire to fender impact occurs.
The black lever is the high speed compression adjustment. The blue knob is the low speed compression. At the very bottom is the rebound adjuster. At full compression of the bike NOTHING in the linkage collides with other parts of the frame/linkage/swingarm. The ONLY impact that occurs is frame to tire and upper linkage to my fender mud guard. Lowering that mud guard will solve that issue.
So during my road racing days I worked with an Ohlins tuner. I’m working with some of their guys to figure out just what I need to do to increase the length by an inch. It may be a new dog bone in the linkage. But for now I’m using the 9.5 inch Ohlins after determining that nothing catastrophic will occur should I bottom out the shock. I don’t plan to do bottom out jumping until I can measure and ensure that the tire will not impact the fender on landing. But until then I just can’t give up the incredible plushness and control of the Ohlins.

Because the Ohlins shock I purchased off of eBay for my bike is a 9.5” and the OEM is 10.5” I needed to have a shock tower extension custom engineered and produced. A few folks have asked me why I didn’t just buy a 10.5 inch Ohlins or a Fox shock. I tried to find an Ohlins 10.5″ TTX22, but could only locate new ones which are 700.00 plus a spring which is another 100.00. I got my 9.5″ one for 397.00 delivered. Plus the 10.5″ Ohlins has a shock plunger length of 3.5 inches. The 9.5″ Ohlins has a 3″ plunger travel. After measuring the maximum travel of a shock plunger is 3.1 inches before the rear tire impacts the subframe. (based on my Shinko 244s which are about 1″ taller in profile than the OEM tires) So I would have to have added a spacer under the shock bumper to avoid having too much travel. Not a big deal, but combine that with an additional 400+ bucks in cost…no thanks.

My OEM shock was the FastAce model. All Sur Ron shocks are 10.5 inches eyelet to eyelet on center.

And although many folks like Fox suspension parts, I’m very familiar with Ohlins from my racing days. So I went with what I know.

I found a craftsman near my home and Gerard measured and designed it out of billet aluminum. It is engineered in such a manner where no flex or movement occurs. Remarkable. After having used the shock now for 12 hours of riding, I will simply say that it has transformed how the bike handles on choppy downhill sections as well as through off camber turns. It feels much more planted on both accounts and in general. Now the front and rear tires react in a similar fashion keeping contact with the ground without a pounding feeling or chatter over bumps large or small. The Dorado’s are now matched in the rear with the Ohlins. Prior to replacing the rear shock, the smoothness and contact of the front end highlighted the weaknesses of the rear suspension.

Gerard measuring and designs the shock tower extension. He transferred all of that into his CAD program.
The little Sur Ron attracted quite a bit of attention at Gerard’s shop when I went back to install the shock tower extension. Loads of questions.
As you can see his engineering of the shock tower extension is well executed.

So what’s different than the OEM shock? Most folks may think that suspension just makes the bumps more smooth. Of course that is ONE of the aspects of suspension. But the aspects of the Ohlins is its ability to make going faster easier and safer is one of the best aspects. Being able to get on the throttle sooner coming out of a turn, reducing arm pump because its high speed damping are all things that are great about the shock. If you’re primarily riding on the street or smooth surfaces, then I would not recommend the effort or money to replace the rear shock.

For any of you who may have purchased the same shock as I’ve bought I’ve placed a link to the user manual below.

Ohlins_DTC_TTX22 Manual

23 Comments

  1. Hi Mark
    I am seriously impressed by by your website! I thought of the sur ron more like a toy bike but now I’m intrigued and will probably purchase one. Thanks for that marvellous page! Cheers from Mallorca Spain

    • Hey Andreas, thank you for stopping by and letting me know you appreciate the site. The ENTIRE reason I took the time to build it was to support the Sur Ron Community worldwide. I was formerly an admin for the Private Sur Ron Facebook group, but I just cannot stomach Facebook’s business practices so I deactivated my account. Obviously you’ve read through my site and know how enthusiastic I am about this new device which in my mind has not existed before, not in this way. If I travel to Spain I will ping you to meet in person. Take care!

  2. 4sure…when in Mallorca give me a ring 😉

    • I’m 180 in gear and use the 502 lbs spring.

  3. Hello I was wondering if I could go with the 10.5 in model of this shock I noticed its shaped a little different?

    • Christian, as long as the eyelet to eyelet distance is 10.5″ the shape of the TTX22 should not affect the clearance of the spring to the shock linkage. As it is in OEM form my FastAce shock’s spring was really close to the rear linkage, but never fouled against the spring. Had I been able to locate a used Ohlins 10.5 TTX22 I would have purchased one rather than the 9.5″ I just didn’t want to spend 900.00 on a new one. This is a TTX22 whose housing is different from mine. But it is the same internally and will easily clear the upper shock mount on the Sur Ron. Just be sure to get the right sized bushing.

  4. This shock tower extension is soooo awesome, thats what I need, is there a way to get one and shipped to germany ?
    Cheers Iggy

    • Hi Iggy and thanks. I’d love to be able to tell you that having one made and shipped to you is possible, but unfortunately it’s not. Gerard did this for me because he is interested in a Sur Ron so when I let him ride mine he was impressed with the bike. I asked him if he could mill one for another owner and he simply said “No Mark I did that for you, not to do it over and over.” He also adjusted my kickstand which I wrote about here. I’d suggest you go to a custom metal fabricator in Germany and ask to have one made. Or purchase the 10.5 Ohlins TTX22. Sorry.

  5. Hi Mark,
    your Sur Ron is awesome and I love to read about the upgrades you performed on your bike. Could you do me a favor and tell me what rear mud guard you use.

    Thank you so much.
    Heiko

    • Heiko thank you. In the upper right hand corner of my site is a search bar. Simply typing in a subject should reveal anything I’ve posted about that subject. In typing fender into that search bar it leads you to this link.

  6. Hi Mark,
    Thanks for putting this all together I really enjoy your site. I’ve taken a few ideas from your upgrades already, I just got a good price on used Ohlins 10.5 TTX22 only catch is no spring but no big deal price was right. Wonder if you had any tips on figuring out what weight spring I’d need? I’m probably 20-25lbs heavier in gear and a bit green in the suspension world.

    • Hey Stephen, thanks for letting me know the site has helped you. So I have a personal way to figure out spring rate. It does NOT mean it’s the right way for everyone, so keep that in mind. I have found that my suspension performs best when the static preload is within 20-30% of the total travel range. So using that math I have found (with my race bikes) that a 20-30% ratio of my geared weight to spring rate is a great starting point. And keep in mind this was back in my racing days when I would change my suspension based on track temperature, weather, tires, etc.

      I don’t change my suspension settings nearly as much as I did back then with my Sur Ron. But I do change it when I ride in conditions which warrant a change.

      So as an example:
      I’m 180 in gear, at 30% for spring rate that would put me at a 600 pound spring – 180 divided by 0.30 gives you that number. Now that would mean my shock would be completely extended for spring tension – the adjustment collar set to maximum extended distance. So if I wanted more static preload I would not be able to adjust it since I’m maxed out. I learned that using 35 to 40% ratio gave me the right spring rate and the ability to have adjustment room for more or less static preload. None of this may make sense based on how I’m explaining it….

      So I use a 502 lbs spring which translates to a 36% ratio to my weight. (180/502). So using my own formula:
      Rider weight = xxx lbs divided by the percentage equals the spring weight. In this case let’s use a 240 lbs rider. 240/0.36 = 666.67 lbs spring.

      I have found that it works well for me. But again, it’s just how I use the formula based on my own experience. A man whose experience I so respect (He was the crew chief for Honda Erion Racing and an Ohlins expert) taught me this formula. He has easily forgotten more than I’ll ever know. Others may use different methods. Suspension is just as much art as it is science. Anyone who feels differently is certainly welcome to their own view. Hope this made any sense and helps.

      • Thanks Mark! I think it makes sense. It definitely makes more sense than it did 5 minutes ago. I have a good jumping-off point now.

        • Hum…five minutes ago? Alcohol? Mary Jane? LSD? LOL

  7. I’m not 100% sure on this yet but it seems like for the 10.5” x 3.5 shock Ohlins does not offer a spring above 434lb. They do offer a up to 571lb with a 3” max travel. So you actually are better suited to use the 9.5” I think. Hopefully I’ll find something closer to the weight I need but no luck so far. I talked with a Ohlins dealer and apparently Ohlins got back to her with an email kinda laughing at “those Sur Ron guys”.

    • “I talked with a Ohlins dealer and apparently Ohlins got back to her with an email kinda laughing at “those Sur Ron guys”.”
      HAHAHAHAHAHAHA

      Well I guess I just lucked out with my 9.5″ model. In reality the adjustment for compressing the spring is much greater than trying to loosen it if you have a spring too heavy for your weight or riding style. You can always go with a different brand of shock too.

      Best of luck.

      • Hey Mark soooo I modeled a shock extension based on photos yours as I ended up going with the same length TX you have. I’m about to have it machined and realized some others might want one of these so I may make more than one. I just wanted to get your blessing before offering these to the wider internet.

        • Hey Stephen, thank you SO MUCH for considering permission. That’s so rare nowadays. Yes by all means make some because as you saw if a 9.5 TTX22 is a better deal/fit in terms of spring weight than the more the merrier I say. Later this week I’m servicing my linkage bearings. I have 3800 miles on my bike, about 2k since I installed the Ohlins so it’s time. Thanks again.

  8. Hi

    Well done with that.

    I just fitted a set of Fox 40’s to the front (eBay special!) and am having the same experience as you! Namely that now the front is sorted the rear feels awful 🙂

    I will say though that the advantage of an air spring on the Fox rear is that it’s fully adjustable. That compares to fixed spring rates of a coil that comes with the Ohlins. Then the need to make a bracket to make up the 1″. Sometimes you’re better just biting the bullet and hitting the trails and don’t forget, when you’re done with the Surron you can sell the shock to someone else and get some cash back.

    • Chris I’m having my bike cremated with me. I don’t want my kids arguing over it when I die. I will just instruct the crematorium to remove the battery before firing us both up! LOL

  9. Aloha Mark, I have the same 9.5” Ohlins shock and was wondering if you could have another shock tower extension made as I’d like to have one if possible. Mahalo! Wayne

    • Wayne brah if I could I would. I had asked Gerard after he made mine. His response, “Mark I did this just for you. I really don’t want to make more.” I would find a metal fabricator near you and let them examine the top shock mount and have them make you one. Sorry brah, I really am sorry.


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