Difference Between Upright & Inverted (USD) Shock Absorber

Published On 06-Feb-2016 01:34pm , By Shuvo

In the last two years Bangladeshi motorbike market has enhanced with various types and models of motorcycles. All the available brand and sub brands in our market tried to rearrange their product line competing for the market position. In sequence the small importers also tried to keep themselves one step forward and imported some fresh models of bike. Some of those bikes came with quite attractive features where inverted shock absorber in front suspension grabbing some added attraction.


Subsequently peoples are hooking behind us to know the benefits of such inverted suspensions. So we are herewith Difference between Upright & Inverted (USD) Shock Absorber. So let’s try to find out what the real thing with this type of suspension system and what the difference with the conventional suspension system.

Upright Shock Absorber:

You know the conventional or regular shock absorbers are known as Upright shock absorber. In the upright shock absorbers the main mechanism therefore hydraulic fluid, cylinder (tube/barrel), valves, piston all the parts are fitted at the lower part of the shock absorber and the piston rod stays upside fitted with the handlebar through the YOKE.


The upright shock absorbers can be build with mono tube or twin tube, where mono tube shock absorbers are build with very easy mechanism and also cost effective. But the twin tube shock absorbers are constructed with quite complex and précised mechanism and quality parts. So the twin tube shock absorbers are quite expensive and heavy duty as well as durable also.

The mono tube shock absorbers are used in old model low priced bike or commuters where manufacturer needed to minimize the manufacturing cost. And some time mono tube shock absorbers charged with gas and sealed forever which can be used as rear part or in other vehicles. But in heavy duty and performance bikes front shock absorbers are manufactured with twin tube mechanism. Here cost is mot main issue but heavy duty, extreme performance and durability is matter. So we can find most of the quality and performance bikes come with heavy duty twin tube shock absorbers. And it is very easy to understand that twin tube shock absorbers are quite fat, weighed and expensive also.

Inverted (USD) Shock Absorber:

Now the point comes, what the thing about the inverted shock absorbers? In straight answer, inverted shock absorbers are nothing but those are quality twin tube shock absorbers same like as conventional upright heavy duty shock absorbers which sometime called as Upside-Down (USD) shock absorber.


Here the hydraulic fluid, cylinder (tube), piston and valves therefore entire mechanism stays at the upside and in inverted position. Here the mechanism part attached with the handlebar through the YOKE and the piston rod connects with the front wheel spindle. In front suspension system of a bike the inverted shock absorbers cannot be mono tube where hydraulic fluid and gas cannot be sealed in inverted position perfectly against heavy shock and mostly significantly against continuous pressure of gravity.

So the front wheel inverted shock absorbers are always comes with twin tube mechanism with high grade of sealing. But again as we stated earlier the mono tube shock absorbers when sealed for permanently those can be used anywhere in upright or innervated position where the shock is not continuous or heavy like the rear wheel or in other vehicles.


Which Is Better?

Now here comes the question which performs better between upright and inverted USD shock absorber where both are constructed with twin tube mechanism? In straight answer both are same. You will find both type of shock absorbers are equally used in renowned branded motorcycles even in higher capacity and performance bikes. But one thing you should notice as their using purposes are not same. Answering more clearly they are used for different model and different featured bikes; here are the reasons, lets concentrate.

You know the cylinder of the shock absorber is full with the hydraulic fluid and other parts like piston, valve etc. So this is the most weighted part of the shock absorber and the piston rod area is the lighter part. And another thing is the first part is fatter and second part is thinner. So here come the reasons considering above points:

  • Firstly to arrange and adjust the weight distribution of a bike. The designer & engineers selects the upright or inverted shock absorbers to do the weight distribution more précised and accurate for their bike.
  • Secondly in consideration of some précised controlling feature where again perfect weight distribution issue comes with significance.
  • Thirdly for some extreme shock absorbing capability or for dealing those situations where longer travel of piston rod playing needed there the inverted type shock absorbers are used. And that feature is only applicable for the bikes like dirt bikes where again weight distribution matter comes in consideration but that specific reason is not applicable for other vehicles.
  • In some situation upright shock absorbers help the front wheel being heavy to stick with the tarmac which is essential for cruiser and some sports bikes. On the other side inverted shock absorbers makes the front wheel lighter so it can be helpful for some sports bike or dirt bikes.


So guys the reasons are quite clear we think. But we should add more briefing in behalf of both shock absorbers. You know longer barrel and fatter designed shock absorber are possible in terms of inverted USD type where fatter and weighted part are attached with the chassis through the YOKE and light weighted and thinner part are attached with the wheel and it doesn’t makes the wheel heavy or leaden.

So in light weighted heavy duty bikes are comes with inverted type shock absorber like naked or dirt bikes or in some heavy sports bike to adjust the weight distribution. On the other side high performance heavy bikes like cruiser or in some high capacity sports bike uses conventional up-right type shock absorbers. So again the most significant term is perfect weight distribution for selecting suspension type. But especially when the longer travel and fatter suspension system needed that can comply perfect with the inverted type.


Which Is Durable?

Again another question raises which is better in terms of durability? In terms of performance both are same if we consider for same size and same construction method as we stated earlier. But most of the time inverted type shock absorbers are designed to be longer or fatter in comparison with up-right type. So the shock absorbing ability of inverted type is far better where piston travel length is long and hydraulic fluid or gas can be compressed or played with spacious area.

But in terms of durability up-right type shock absorbers are more durable than the inverted type. As we mentioned earlier in inverted shock absorbers the hydraulic fluid and gas sealing parts stay in inverted position where the sealing parts and the valves had to absorb more pressure, where the pressure of gravity added continuously and most of the time the pressure multiplied when running in high speed.


So the sealing parts and valves can be damaged very frequently. And if quality parts are not used in the entire mechanism the user had to face very frequent maintenance or replacements of some parts. But not to worry if those are manufactured and assembled ensuring quality and high accuracy. That’s it.

So guys that was all about our discussion on Difference between Upright & Inverted (USD) Shock Absorber. If you have more questions or need further explanation considering this matter please feel free to drop your massage in bellow commentary box. We will try to respond your queries within our means. Therefore stay connected with us and thanks for staying with us.

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Published by Shuvo