Go Back   Motorcycle Forum > Motorcycle.Com General Discussion > Motorcycle News > Old News > MO Reader Feedback

Reply
 
Thread Tools
Old 10-23-2002, 04:56 PM   #1
FrankS1
Founding Member
 
Join Date: Nov 2001
Posts: 156
Default Re: Rear Suspension - Mono Shock vs. Dual Shock

The point about available room is a good one, but a monoshock has one definite advantage: It's easier to tune.



Many monoshocks are fitted with variable linkages, so that effective spring rate and damping can be increased or decreased as the suspension moves off "neutral" position. As I type this, I can't think of any dual shock setups I've seen that incorporate variable linkage (OK here comes the onslaught of counterexamples - have at me, folks) unless you count the variable attachment point used by Velocette about 40 years ago.



Of course, variable rate springs and very fancy valving in the damper units could do everything a variable linkage accomplishes, but it would surely be more expensive to manufacture. Not only that, but a suspension tuner can surely (within limits) fab and install new rods and linkage parts to change the geometry with straightforward and readily available machine shop facilities. And the manufacturer can fine tune the linkage during final product development without upsetting the whole production operation.
FrankS1 is offline   Reply With Quote

Sponsored Links Remove Advertisements
Motorcycle Forum
Advertisement
Old 10-23-2002, 05:32 PM   #2
seruzawa
The Toad

 
seruzawa's Avatar
 
Join Date: Nov 2001
Location: 8501 ft.
Posts: 17,461
Default Re: Rear Suspension - Mono Shock vs. Dual Shock

From my personal experiences I've come to feel that bikes I've ridden with monoshock are less subject to wallowing in hard turns. This could be more a factor of the improved frame designs that reduce flexing, though.



I'm certainly no expert, but it seems logical that a dual shock setup has the liability that one shock is going to compress differently than the other no matter how carefully you try to tune them. Monoshck eliminates any possibility of an imbalance between the two.



Another advantage would appear to be weight saving.



All this in addition to FrankS1's comments about the ability of monoshock systems to allow the design of variable rates.
__________________
"Make no mistake, Communism lost a big argument - one we know today as the 20th century."
seruzawa is offline   Reply With Quote
Old 10-23-2002, 06:03 PM   #3
Captain_1
Founding Member
 
Join Date: Jun 2007
Posts: 157
Default Re: Rear Suspension - Mono Shock vs. Dual Shock

Its not so much a question of which is better, it all depends on how well the suspension is designed for the application and quality of the components.
Captain_1 is offline   Reply With Quote
Old 10-23-2002, 07:01 PM   #4
northman_1
Founding Member
 
Join Date: Jun 2007
Posts: 1
Default Re: Rear Suspension - Mono Shock vs. Dual Shock

A single shock would of course have less unsprung mass, so, possibly better performance. Of course it's all down to the design target. As for wallowing or not, I think that also falls into the design target. In other words, generally, single shock models are more "perfomance" targeted.
northman_1 is offline   Reply With Quote
Old 10-23-2002, 07:50 PM   #5
ossa
Registered Member
 
Join Date: Jun 2007
Posts: 8
Default Re: Rear Suspension - Mono Shock vs. Dual Shock

I can certainly see that a monoshock rear suspension would produce a more rigid feel as the wheel moves through its travel, but I seriously doubt (depending on the materials used) that it would weigh less than a two-shock system. Keep in mind that a monoshock has to do the work of two shocks, so it must be a beefier unit with a bigger spring (maybe a larger gas/oil reservoir too). The monoshock swingarm with all its linkage and adjustment pieces add to the weight of the rear suspension system.
ossa is offline   Reply With Quote
Old 10-23-2002, 10:11 PM   #6
JLittler
Founding Member
 
Join Date: Nov 2001
Posts: 17
Default Re: Rear Suspension - Mono Shock vs. Dual Shock

True, a mono shock does have to be beefier, but don't forget about the differences in mount points and hence the impact of leverage on what becomes unsprung weight. In other words the monoshock being further away from the rear wheel has less impact on unsprung weight. The difference in leverage however means the monoshock has to control a stronger force (longer lever ie the swingarm) and hence may be heavier than twin shocks. Unsprung weight is however more significant for handling than overall weight.....







JLittler is offline   Reply With Quote
Old 10-24-2002, 03:16 AM   #7
RonXX
Founding Member
 
Join Date: Nov 2001
Posts: 273
Default Re: Rear Suspension - Mono Shock vs. Dual Shock

It seems that you really don't know what you are talking about when it comes to levers and springs. There aren't many monoshocks that are mounted far forward without linkages to decrease the force/amount of compression among other things. In addition, the only part of a shock that will contribute to unsprung weight is the lower half of the shock body. This is because the upper half is supported by the spring, and the spring itself is in some state of quasi self support. In other words, if I put the swingarm/wheel/tire/brake/etc. on a scale it will weigh the same for 2 shocks or 1.
RonXX is offline   Reply With Quote
Old 10-24-2002, 05:51 AM   #8
everiman
Registered Member
 
everiman's Avatar
 
Join Date: Nov 2001
Posts: 67
Default Re: Rear Suspension - Mono Shock vs. Dual Shock

It ain't how many shocks, but the quality of the ones you got. Early twin shocks were of low quality. Performance was inconsistent between a pair of shocks. Combined with spindly swing arms there were all kinds of handling problems. Girling sold 'matched' pairs for extra dollars.



Replacing low quality stock shocks with high quality aftermarket units was one of the first things a serious rider would do. The rumour was that japanese shocks of the 70s used fish oil for a damping medium. Any damping ability they had usually disappeared after 5000 miles or so.



It costs as much to build a single shock as it does to build two, all other things being equal, which is probably the biggest reason that single shocks are so popular with bike makers today.
everiman is offline   Reply With Quote
Old 10-24-2002, 06:24 AM   #9
Vlad
Registered Member
 
Vlad's Avatar
 
Join Date: Nov 2001
Posts: 295
Default Re: Rear Suspension - Mono Shock vs. Dual Shock

The baseline problem with dual shocks is that there will always be variables between two shocks. Simple manufacturing tolerances assure that there will be differences, albeit slight, between two units. Over time these differences will increase. A monoshock set up eliminates the possibility of these differences. Does the difference really matter if you're not riding hard? Probably not. It's like single-sided swingarms. They're a great idea, but a dual sided is more stable.



Vlad
Vlad is offline   Reply With Quote
Old 10-24-2002, 06:31 AM   #10
pplassm
Founding Member
 
pplassm's Avatar
 
Join Date: Nov 2001
Posts: 3,875
Default Dual shocks with linkage set-ups

I remember a couple of designs that were available on dirt bikes in the '70s. One example was the last series of Ossa MAR/Plonker trials bikes that came out. I think the trade name of the linkage set-up was Bolger.



Sorry. Couldn't resist.
__________________
Mongo just pawn in game of life.
pplassm is offline   Reply With Quote
Reply


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off