Topic: monoshock, what benefit?

[traveler]

Curious....

What is the benefit of having a monoshock suspension in the rear versus a dual shock arrangement, if both are set up for handling.

There MUST be a reson besides the looks.

Thanks,

~Joe

[MCRider]

Curious....

What is the benefit of having a monoshock suspension in the rear versus a dual shock arrangement, if both are set up for handling.

There MUST be a reson besides the looks.

Thanks,

~Joe

There are some potential handling benefits from the design that a 2 shock system no matter how good, cannot duplicate. Basically, builders would strive to get all weight within a triangle descrbed by the front and rear axles and some point above the tank centered between the axles. For center of gravity reasons. (This is why putting a battery in the seat cowl makes me cringe, though it does allow for a cleaner look.)

A monoshock puts all the shock weight within that triangle, the 2 shock never can. It also usually has less unsprung weight. This is the weight that is below the halfway point on the spring. It is the weight that travels up and down and a builder would want to reduce that to a minimum. (That is why i have trouble with fat wheel/tire combos on a cafe racer.) A monoshock has only one shock body, albeit slightly larger, but still is less than 2 shock bodies. The mono shock body also travels a lot less distance which is good for momentum restriction.

It is also the reason why higher performance shocks, front and rear, are mounted upside down, to reduce unsprung weight.

But for most riders, a well done 2 shock system will outperform their ability to ride it and the monoshock is overkill.

[traveler]

okay...thanks.

I thought doing it to my bike at some point may look cool, but wanted to know the performance difference.

My little A123 battery weights about 1-2 lbs....so I don't have to worry about adverse weight handling woes, thank goodness!

Yeah.....I can't ride good enough to see the difference.

~Joe

[MCRider]

Didn't realize you had put the bat in the cowl, no offense meant, and at 1-2 lbs, no foul.

I can't ride good enough for it to matter either, but i appreciate the efforts and design theory.

[sangyo soichiro]

Curious....

What is the benefit of having a monoshock suspension in the rear versus a dual shock arrangement, if both are set up for handling.

There MUST be a reson besides the looks.

Thanks,

~Joe

There are some potential handling benefits from the design that a 2 shock system no matter how good, cannot duplicate. Basically, builders would strive to get all weight within a triangle descrbed by the front and rear axles and some point above the tank centered between the axles. For center of gravity reasons. (This is why putting a battery in the seat cowl makes me cringe, though it does allow for a cleaner look.)

A monoshock puts all the shock weight within that triangle, the 2 shock never can. It also usually has less unsprung weight. This is the weight that is below the halfway point on the spring. It is the weight that travels up and down and a builder would want to reduce that to a minimum. (That is why i have trouble with fat wheel/tire combos on a cafe racer.) A monoshock has only one shock body, albeit slightly larger, but still is less than 2 shock bodies. The mono shock body also travels a lot less distance which is good for momentum restriction.

It is also the reason why higher performance shocks, front and rear, are mounted upside down, to reduce unsprung weight.

But for most riders, a well done 2 shock system will outperform their ability to ride it and the monoshock is overkill.

Excellent post Ron!

[weekend_junkie]

CG and unsprug weight are big improvements, but I understand that a single shock is also superior because dual shocks will promote swingarm twisting and effectively have different rebound rates when coming out of hard corners.  Again as Ron said, this is beyond the skill of 99% of riders.

Just to be a stickler for detail, isnt' "monoshock" trademarked by Suzuki?  I think Honda's "pro-arm" suspension is their proprietary hardware.

[traveler]

yeah....but I reserve the right to call it a monoshock, whether Suzuki likes it or not!

~Joe

[kos]

Along with the benefits of having only one shock body and thus lighter weight & better centralized mass, the real benefit is the adaptation of true rising rate suspension... due to use of linkages between the shock and the swingarm.  When Yamaha, who owns the name "monoshock" first arrive it was nothing more than a single long shock and spring attached to back of steering head and routed under fuel tank, back to a triangulated swingarm mounting point. This system did not have a linkage to change the rate of susspension, as it operated through its range of movement.  And in the time it was better than two shocks, mostly due to it was very hard to make any two shocks that close in performance... due to state of the art of manufacturing at the time.

IE: You did not have to try match two shocks to each other when using only one shock.

It was only later when the Japanese manufactures added the linkages to the "system" that they became much better handling motorbikes.

KOS

[sangyo soichiro]

You guys are making me want to go out and buy a modern crotch rocket!  (I've sort of been wanting one for a long time anyway....)   

[MCRider]

Thanks KOS, for the addtl info, I was sure i was leaving stuff out.

Love to hear from those that live it.

[kos]

Your welcome and to sharpen the pencil just a bit more, here are the names that the respective manufactures used in their sales brochures.


Monoshock by Yamaha (for original version with no linkage)

Monocross was Yamaha's name when they added linkage. (yamaha also used the name Mono-X)

Uni Trak by Kawaaski

Pro Link by Honda

Full Floater by Suzuki

KOS

[kayaker43]

I had a single shock rising rate linkage on my CB590 racer in 1978. It was inspired by the early Bimota and Suzuki "Full Floater" of that era.

I've been watching the trend ever since and the early designs had an aggressive rising rate that has all but disappeared now. Even on dirt bikes, the spring rate curve is fairly flat with less than a 10% rise at the end. Considering dirt bikes need the ability to land from 60 foot jumps, I can see the need for a rising rate at the end. Keep in mind that the damping is also ramped up with the spring rate as opposed to a progressive spring only. Also notice that KTM and others have done just as well with no linkages. You can get a similar rate gain through simple geometry and can get a damping increase with internal shock tricks. I think linkages are still relevant to supercross but not needed for woods riding or anything without big jumps,.. hence the success of KTM in the off road market.

I don't believe a linkage is even remotely neccessary for street or roadracing. The rising rate curves there have been getting more linear to the point where you can get the same results using simple geometry and no linkage.

Now its all marketing, after decades of buzzwords and hype, its hard for any manufacturer to admit its not needed, and customers just expect a linkage to be there. I hope to build a custom frame soon and it will have a single shock with no linkage. This has all the benefits of mass centralization but less weight than a linkage system.

[kos]

News Flash

KTM is now selling some new models with linkages in single shock versions.

KOS

[simon#42]

I had a single shock rising rate linkage on my CB590 racer in 1978. It was inspired by the early Bimota and Suzuki "Full Floater" of that era.

I've been watching the trend ever since and the early designs had an aggressive rising rate that has all but disappeared now. Even on dirt bikes, the spring rate curve is fairly flat with less than a 10% rise at the end. Considering dirt bikes need the ability to land from 60 foot jumps, I can see the need for a rising rate at the end. Keep in mind that the damping is also ramped up with the spring rate as opposed to a progressive spring only. Also notice that KTM and others have done just as well with no linkages. You can get a similar rate gain through simple geometry and can get a damping increase with internal shock tricks. I think linkages are still relevant to supercross but not needed for woods riding or anything without big jumps,.. hence the success of KTM in the off road market.

I don't believe a linkage is even remotely neccessary for street or roadracing. The rising rate curves there have been getting more linear to the point where you can get the same results using simple geometry and no linkage.

Now its all marketing, after decades of buzzwords and hype, its hard for any manufacturer to admit its not needed, and customers just expect a linkage to be there. I hope to build a custom frame soon and it will have a single shock with no linkage. This has all the benefits of mass centralization but less weight than a linkage system.

you are right , most modern rear suspension has very little rising rate [ although they do have a linkage , this is normally to do with the positioning of the shock and not the rising rate ]. the reason this works is because shocks have improved so much over the last 20 years  , the early monoshock bikes needed the rising rate to make the crap shock work

[kayaker43]

Kawasaki Versys has no linkage, sometimes customers or sylists drive the design instead of the engineers?

Cannondale had their ohlins shock mounted at an extreme angle that gave a rising rate equal to linkage bikes. The KTM is not quite as extreme and needs a progressive spring to match a CR250 spring rate curve. http://www.racetech.com/articles/ktm.htm

I agree that linkages still have some merit on dirt bikes, just can't see the need in street bikes? Maybe its the mechanic in me who hates the slop, maintenance, and weight? Other  than that, theres nothing wrong with it  

[Sam Green Racing]

In the early days, this type of suspension set up was refered to as cantileaver suspension and Yamaha laid claim to the design. I'm not sure if the design was not patented but Vincent were using it in the 40s I think, defo in the 50s but their design used 2 shocks or a double shock.

Sam.

[Pinhead]

The advantage I see is the ability to triangulate the forces to keep the frame good 'n stiff. But that's just from me eyeballing various pictures of frames on the 'net.

[lordmoonpie]

In the early days, this type of suspension set up was refered to as cantileaver suspension and Yamaha laid claim to the design. I'm not sure if the design was not patented but Vincent were using it in the 40s I think, defo in the 50s but their design used 2 shocks or a double shock.

Sam.

Oooo so here's a trivia question for you lot of clever heads - who was the first manufacturer to use a single shock rear suspension? Was it Yamaha by default or is there some old Cholmondeley-Featherstonehaugh 350 out there with one on? 

[kayaker43]

Vincent Black Shadow has one,.. still probably not the first. They were still experimenting back then before we got stuck in the telescopic forks/twin shocks rut.

[simon#42]

the vincent was not really a monoshock as it used two shocks side by side , no idea who had the first true monoshock , the first one i can remember was on a yamaha racer , early 70s

[turboguzzi]

phil irving was way ahead of his time but so were NSU in 1914....

I cant be certain that there is just one spring in there at the back (looks like), but they surely beat Irving on the sprung rear triangular swingarm idea by quite few years. amazing.

what a company it was, a 50's NSU 250 Max with eccentric cam drive (monoshock too BTW) is still very high on my "gotta have one" list.

http://www.flickr.com/photos/10983301@N06/2236910846/in/set-72157603838957001/

So LMP, can I choose the prize? A spin on your CR maybe?

TG

[simon#42]

what a fantastic bike , it is amazing what people where doing nearly a hundred years ago

[Retro Rocket]

I have read that mono shock design has been around since the early 1900's. The Vincent had 2 shocks..

Mick