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F: Frame Series D Rear Suspension

peter holmes

Well Known and Active Website User
VOC Member
This review is long overdue, I apologise to Rob Staley for taking so long to write it.

At the back end of last year, around the time when you realise that motorcycling is coming to an end for another year, for me anyway, I was contacted by Rob Staley, who in conjunction with Avo was developing a new Series D rear coil over shock absorber to replace the original Armstrong unit. Rob asked me if I would be willing to use my Seried D Comet as a test bed, I immediately said yes as I had already used the Standard shock and also a Spax unit, both of which came well short of the performance levels that I was hoping for when I purchased my Series D Comet.

I should preface this review by stating that I go pretty much everywhere 2 up, and I think that equates to around 25 stone when fully clothed etc. and with a little luggage in a tank bag.

The first prototype I tested was a standard length AVO shock with a 10 inch 300lb spring, I found that bottomed out far to easily, although already by far the most comfortable the bike had ever been, even with the damping adjusted to the maximum.

Rob and Avo then came up with an interesting idea, especially for me, being shall we say a little short in the leg, they were able to reduce the stroke of the shock by about half an inch I think, this reduced to seat height to a more comfortable height for me, without losing any perceptible comfort of the shock, the spring length was also reduced from 10" to 9" but the spring strength increased from 300lbs to 350lbs, it now became a very comfortable shock, but still required maximum damping to stop bottoming out on bumpy roads, but we were nearly there.

I asked Rob if AVO would be able to supply a 9" 400lb spring for comparison, by now I had the swap over times down to minutes instead of hours, I think Rob was concerned that the shock might suffer from topping out instead of bottoming out, this has not been the case, I am still using pretty much maximum damping and I find it really comfortable, even when riding solo, although probably marginally better when two up, I forgot to mention that pretty much all the tests were carried out with virtually no preload of the spring, just enough to stop it rattling. I do not know much about how the internal damping works, but the difference between the lowest setting and the highest setting does not seem that great, but I am happy with the maximum setting, I guess I could back it off a little when riding solo, which I will be doing a bit more of since Sue ruptured her achilles tendon at the international rally, so no riding for Sue for a while, not even at the Annual Rally, but we will attend.

So in conclusion, I am very grateful to Rob and Avo, I cannot imagine that there will be huge demand for these shocks, unless we convert all our B + Cs to Ds, not many companies would have taken this project on, are there any drawbacks at all, well it requires a little more effort to yank the D stand handle up, but I counteracted that a little by cleaning and lubricating all the relevant pivots points, anyway it has saved me money as I no longer feel the need to purchase a Bullworker, but all joking aside, it does require a little more effort, but nothing when compared to added comfort to the bike.

Cheers Peter

Gary Gittleson

Well Known and Active Website User
VOC Member
Inasmuch as I am also short of leg and ride a D, I find this intriguing. I ride solo and my bike is a Rapide. I'm wondering if anyone with a twin has made this conversion and what his/her experiences are. I have a Thornton on the rear now and find it a little harsh riding as well as somewhat taller than I'd like.

Thanks for posting this.

peter holmes

Well Known and Active Website User
VOC Member
Gary, I think the D seat was somewhat of a compromise, once the seat became static, as opposed to bobbing up and down with the rear frame member as with the B + Cs, there arose a clearance problem, especially with increased suspension travel, to overcome this problem the seat sat a little higher, the mudguard seat cutout was a little larger and the seat covering was a little thinner, and less comfortable, I had my seat recovered by a very well known chap in the UK who did a great job of making the seat a more comfortable, but in doing so also made it a little higher, you might notice the word little crops up quite a bit here, but all those little increments leave me on tippy toes, the new AVO shock pulls the rear frame member up a little which reduces the seat height, and for me that is very welcome. I don't think the new shock is that expensive, around £200.00 I believe, and at a small additional cost you can purchase additional springs of different strengths to fine tune to your own requirements. I think Rob and Avo have done a great job, why not give it try, see what you think, I am sure Rob would welcome any suggestions.

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