Smithage Hybrid Girderfork/Telefork dual suspension

This does have adjustable trail which I will go into the details later on......it also has adjustable wheelpath for the link suspension...and it has two positions of wheel travel and wheel rate...does anybody know how that can be done?

I very much doubt it from my end of things...its an experiment to see if the state of the art in front suspension can be improved upon....so far I think it works well and it shows promise,but is that enough to justify the increased weight/complexity/expense etc...time will tell.

160mm travel conversion done....The 160mm travel fork with the 55mm travel link will give almost the same axle to crown height of the stock bike which is 609mm..... versus 606mm for the dual suspension combo.....interestingly I plan also to experiment with the full 200mm travel fork but using the 27.5 FOX40 lowers and a 27.5 front wheel as shown in the pic....this combo will give a axle to crown height of 625mm but with the 19mm ish smaller wheel radius etc.... and so conserve the bikes overall geometry but with 255mm total travel and see what that has to offer.

Reducing weight is always an interest :-)....especially in an inovation that adds weight....Topology etc is certainly a way forward....something to think about.

Cheers buddy,much appreciated 

Something which I am sure most are curious about is how much does it weigh?.....well a quick comparison between the bikes original FOX40 forks straight off the bike sees the original forks at 3044g.....the Smithage system as shown is 4196g....so a 1152g increase....make of that what you will.

Notice the bar height will be quite a bit higher...31mm higher once on the bike.....so a flat or low rise bar for sure.

Heres a quick reveal of the bike which still a work in progress...still a bunch of small details to sort out and tidy up but its come together nicely....no hidden surprises or miscalculations so far.....

Will do

That is good to know...cheers for the offer mate...yes this is a case where further reducing grams is measured in almost hundreds of dollars per gram.....👍

Presently tinkering with the starting baseline setup for the dual suspension.

I am using a Ohlins TXC2 Air shock which is ideal in size and configuration to be packaged in a very compact way within the linkage and against the bikes steering head....keeping steering inertia about the steering axis to a minimum was a key design goal as I learnt with the previous single crown design that high steered inertia negatively impacts on steering feel...especially when steering angles are around 62/63 degrees.
Also this Ohlins shock is a XC shock so it has a lot of built in Platform for the compression damping circuits,it appears that this may be the way forward to give a better balance between the telefork and the linkage....the telefork nice and buttery and linear and the Link damped and sprung much firmer and more progresive.
Anyways I performed a quick initial setup with adjusting air pressures to set rider sags...the Fox fork at 100psi for 30mm rider sag and the Link Ohlins shock set to 95 psi with 3-4mm of rider sag...with the Ohlins shock being run with a 1:1 leverage ratio but valved to run in a rear suspension with something like a 2:1 motion ratio or higher and hence a higher operating pressure of around 200psi and higher.....I needed to revalve the Ohlins shock rebound valving to suit the 95psi..which I then proceeded to do....the compression damping I will leave for another time as I want to see where the present setting feels with initial testing.
So now I need to find out what the air spring characteristics of the Ohlins shock and the shortened Fo 40 fork are.
I have run the Ohlins shock in my Laba7 spring force dyno and this gives me the spring forces and progressivity the shock is giving...being tested at 95psi and no internal volume spacers...this is my baseline setting.

Later I will test the Fox fork in the same machine....the stock 200mm original forks and the shortened 160mm travel fork.

Ah see you are starting to think out of the box…good to see….once you start doing that all kinds of possibilities start appearing….its then just a matter of sorting out what combination works best for a given situation.

This is basically two suspensions in series…the challenge lays in working out how to design and configure them so they work in harmony with each other in a balanced fashion…..my experience to date is telling me that this is best done by differentiating them as much as possible…although there is probably going to be a differential sweet spot in there somewhere…..such as….making the telefork soft and long travel so it has a lower natural frequency and higher amplitude….the link is the opposite….stiff and short travel,so it has a higher natural frequency with lower amplitude….then go a step further by differentiating their respective wheel paths…..hence making them more or less sensitive to certain force vector inputs at the wheel…yada yada….its all a work in progress with still lots to learn and work out.

Just completed putting the second Smithage system on my Kenevo comp....this runs a Fox40 with the 27.5 lowers at 160mm travel with a 27.5 front wheel in keeping with the bikes original wheel sizes....

The bikes original 180mm fork and axle to crown / fork length of 572mm is now 587mm with 160mm fork and 55mm Link travel for 215mm total travel....this extra height in the front and consequential change in steering geometry is a little offset by running a 2.3 front tire replacing the stock 2.6 front  and a 2.8 rear tire replacing the stock 2.6 rear.

Edit : correcting error in geometry/measurement changes.

So been out riding the Kenevo with my dual front suspension system now for over a week now and very very happy with it....alot of fun.
Been just trail riding it taking the time to get to know the personality of the system...so no big jumps or challenging gravity riding yet.
Zero problems with it so far and been out smashing it into all kinds of things with no issues....this is on a 25kg E-bike and me at a porky 110kg.
Compliance/sensitivity is next level and big hit performance.... its so confidence inspiring....and its far less tiring to ride on the arms/upper body.
When hitting big roots/rocks/ruts etc there is far less spiking coming through the bars into my arms and the bike as a whole is deflecting less so directional control and stability is enhanced.
The Fox40 forks are bone stock apart from reducing them to 160mm travel and additional volume spacers to suit...I do need to also reduce the volume of the balance chamber as the forks do feel a bit to soft in the mid stroke...I think just adding maybe 35ml of oil here may do the job.....anyways but just to make things interesting I put the forks back to 200mm travel and that hence gives me total 255mm travel with the additional 55mm travel of the Links....wow it just feels even better.
Now people are no doubt thinking what is THAT doing to the bikes steering geometry....well its all good....
I wont yet go into the specifics of the resulting steering geometry I have been using but yes it changes things quite a lot...but its helped by the stock Kenevo running a 64 degree steering angle to begin with...but the biggest issue would be one of offset and resulting trail...this normally being a big issue on normal teleforked bikes as there isnt much of a range of fork offsets to chose from...so its always a compromise.
The difference here is that I have adjustable offset built into the Link structure....the front upper link pivot uses oval flip chips which I can change to alter the angular orientation of the upright/crown and hence forks/wheel in relation to the steering axis...but without changing the Kinematics of the Link suspension.....hence adjustable offset and so trail....range of adjustment is 24mm with the basic starting geometry in the middle..so roughly 12mm of adjustment each way....13 different overall offset choices with 1.8mm offset increments
This is a game changer...having played with the full range of max to minimum offset/trail I can run....and with the 160mm fork and 200mm fork.... it gives the ability to tune the steering geometry to tight trail,light and fast to DH heavy and stable and any where in between to suit trail type and conditions with less compromise...swapping around or changing the chips is simple and can be done on the trail with a couple of basic tools...just dont drop them in the leaf litter :-)

It gets better.....I also have an adjustment that allows me to change the wheelpath of the Link suspension....at the rear pivot of the upper link is also using oval flip chips which I can easily flip or change....
There are 7 paths to choose from from 50 degrees rearward to 63 degrees more vertical ( closer to a typical telefork wheelpath ) in roughly 2.1 degree increments...the effect here is dramatic.
Again running the full range of adjustment the difference felt by going from 50 degrees of plush big hit rearward absorbance to the more vertical 63 degree wheelpath is noticeable....what this gives is the ability to tune the suspension for rock gardens for instance at 50 degrees or change it to suit bike parks with smooth hard pack surfaces/heavy cambered corners etc....the more vertical wheelpath better loads the front  tire more vertically and hence will give more consistant grip on harder surfaces.

Anyways at present I am looking to make some minor changes to the Ohlins front shock as its hydraulic bottom stop is a little to agressive and I need to soften it to make the last 8mm of travel more available...its high speed compression seems quite good and Reb feels great at the present stage of testing with 95 psi.

The Kenevo with 200mm fork and 255mm total travel.

Not yet…..just going through the motions of familiarising myself with it and sorting out the setup and making sure it’s fit for purpose…the Data collection is next up.

Thanks Buddy...this is 2 yrs work so far and overall 8 yrs investigating the concept of a dual front suspension system in other disciplines....been a great learning experience....not done yet :-)

Testing is ongoing....having a ball...such good fun...the Kenevo is currently running the Fox40 27.5 wheel in the full 200mm travel with a Vorsprung smashpot coil conversion which is superbly smooth and buttery...this along with the link secondary suspension gives 255mm of next level overall compliance and capability....soooo confidence inspiring and good fun.
Data collection is a V3 Pro BYB telemetry system which is superb....a really capable bit of kit which I am still learning.


A quick look at some data above....this is a single event hitting a very large bump at around 44kph.....I have three travel sensors on the front of the bike...front left with the green trace is overall wheel travel of both suspensions.....front right with the white trace is the Fox40 fork travel and Rear with the orange trace is the Ohlins front shock/linkage travel.
To the left shows the overall data for each of suspension travel....velocity and accleration in both compression and rebound.
Some of whats interesting here is the comparative velocity recorded by each sensor.....the green trace of the overall suspension travel shows a peak velocity of 10133 mm/s with a peak travel of 238mm...this is a big hit....
The white trace of the Fox40 fork travel shows a peak velocity of 8614mm/s and travel of 181mm
And the orange trace of the Link Ohlins shock at 2092mm/s and 46mm travel.
This shows how the two suspensions working in series are each sharing the job of reacting to and absorbing the bump.....each damper is showing a reduced peak velocity compared to what the wheel is moving at....this is reducing peak stress on each damper and should help make tuning the dampers to handle such high wheel velocity events much easier...it should also be seeing a higher overall damping coefficient which can be seen in how quickly the front suspension returns to equilibrium after the bump event.....hence why this is so confidence inspiring and forgiving....and fun.