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Discussion Starter · #1 ·
I have a FS bike I ride. Max rear travel is listed as 112mm (4.4"). It came with a 165x38 rear shock. I reworked the bracket and got a 190x50 on it. The bike feels really good with the longer travel shock.

Today on the rack I realized I could fit a 216x63. Easily. Easier than getting the 190x50 on.

But do I want to mess with the leverage ratio like this? From 3.0 to 2.3 to 1.8!?! I'm 210 so I need a lower ratio but a 1.8? Anyone have an opinion? I'd be using a Monarch RT3. Thanks.
 

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So, you are putting a longer stroke shock on the bike (I assume by shock "travel" you actually mean "stroke"), but not increasing the actual travel of the suspension?
 

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What you are saying is simply impossible to happen without increasing the bb height and changing the geometry since you are changing not only the stroke but also the i2i lenght.
 

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Discussion Starter · #5 ·
I heard all that before when I made the original change. The bike always moves in the same arc based on the fixed points. I'm only changing the rear mounting location of the shock along the "swing arm" pieces.
 

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What you are saying is simply impossible to happen without increasing the bb height and changing the geometry since you are changing not only the stroke but also the i2i lenght.
Not if he's doing what he says - moving the mounting point on the lever that drives the shock. Obviously other issues could arise from this change as the frame was not designed to be run this way.

But really my first thought is unless he was having issues blowing up shocks i'm not sure why this would even be necessary - plenty of people heavier than 210 have and do ride 3:1 frames without any issues.

OP - you have any pics of your mod?
 

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Discussion Starter · #7 ·
There are no issues, just curiosity. And the bike felt terrible with the original shock and feels perfectly balanced now. So I'm curious if an even bigger shock with more fluid and air would be even better.

Link for post
 

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Dropping leverage ratio is not that big of a deal. If the travel numbers are met, the lower ratio will make the shock, shims and fluid work less. The spring itself, whether air or coil will require less force also.


How low can you go, for grins, consider a fork is 1:1.

The thing to look at though is not the total leverage ratio, comparing extension to compression wheel travel vs shock travel. You should consider how the leverage ratio plots during movement of the suspension. This will see how easily the bike is supported and remains supported. AKA the infamous rising rate vs falling rate or a combination of both. What is a bummer about an airshock is that inherently by design of the airspring, you get a natural riding rate of the spring, but the damping does not follow the spring.

PK
 

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Discussion Starter · #9 ·
What about all the concern over stiction at low leverage? I've never seen my shock work hard at overcoming any internal friction (210psi).... seems the friction is greatest at full extension and mostly nonexistent through the rest of the range... but that is unscientific analysis on my part.
 
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