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maz20

Maximizing rear shock travel

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maz20
I'd like to upgrade the rear shock for a plusher ride (I commute in city traffic on it almost daily), and it seems with a new shock I can also gain some more travel as well. I'm 6'2" (~32" inseam), and don't mind having a higher seat heat (not to mention, a more "forward-leaning" posture might be nicer too!).
 
But, is there a "maximum" amount of travel I can increase to? (Before, that is, bumping into some mechanical limitation!)

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Beemer
Just a heads up but you might want to take a look at my thread I just posted about riding posture before you buy new bars. 

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blackout
I'd like to upgrade the rear shock for a plusher ride (I commute in city traffic on it almost daily), and it seems with a new shock I can also gain some more travel as well. I'm 6'2" (~32" inseam), and don't mind having a higher seat heat (not to mention, a more "forward-leaning" posture might be nicer too!). 
But, is there a "maximum" amount of travel I can increase to? (Before, that is, bumping into some mechanical limitation!)
A slightly longer shock with a slightly longer stroke would do what you want.  A 1/4" longer shock might give a 1/2" more travel, not sure.  But I do know a 3/16" shorter dog bone link adds 5/8" of height to the bike, but not sure if the motion ratio is the same for the shock.   
Anyways, we know there is room to go about 1 inch higher in rear axle height because many have changed their suspension link.  So, increasing rear height by 1 inch by installing a longer shock with more travel would work fine.  Watch your chain tension throughout the travel of the suspension so it does not bind up.  The chain can get tighter at certain parts of the suspension travel.  That can be checked with the shock off and moving the suspension through it's travels.

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maz20
I'd like to upgrade the rear shock for a plusher ride (I commute in city traffic on it almost daily), and it seems with a new shock I can also gain some more travel as well. I'm 6'2" (~32" inseam), and don't mind having a higher seat heat (not to mention, a more "forward-leaning" posture might be nicer too!). 
But, is there a "maximum" amount of travel I can increase to? (Before, that is, bumping into some mechanical limitation!)
A slightly longer shock with a slightly longer stroke would do what you want.  A 1/4" longer shock might give a 1/2" more travel, not sure.  But I do know a 3/16" shorter dog bone link adds 5/8" of height to the bike, but not sure if the motion ratio is the same for the shock.   
Anyways, we know there is room to go about 1 inch higher in rear axle height because many have changed their suspension link.  So, increasing rear height by 1 inch by installing a longer shock with more travel would work fine.  Watch your chain tension throughout the travel of the suspension so it does not bind up.  The chain can get tighter at certain parts of the suspension travel.  That can be checked with the shock off and moving the suspension through it's travels.
 
Why would the chain bind up with increased travel? Would there be something in the way?
 
AFAIK maximum chain stretch (at least when standing still!) is whenever the swingarm joint sits right between the sprockets (i.e., swingarm joint and sprocket centers are all on the same line). And I'm sure that position still happens even with the stock shock as well, so it doesn't seem like increasing travel should affect anything there..
 

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YZEtc
He means that if you were to mount a longer shock, use a different rear shock link, or make any change that resulted in more rear ride height via more swingarm angle and then adjust your chain slack to the spec. recommended in the Owner's Manual, you would them likely have too little chain slack for when the swingarm moves upward and aligns the front sprocket, swingarm pivot, and rear axle.
In other words, if you have more swingarm angle, the chain slack will need to be a bit more loose with the bike unloaded.

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ralph
They may be in line but not on the same axis.
 

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blackout
A slightly longer shock with a slightly longer stroke would do what you want.  A 1/4" longer shock might give a 1/2" more travel, not sure.  But I do know a 3/16" shorter dog bone link adds 5/8" of height to the bike, but not sure if the motion ratio is the same for the shock.   
Anyways, we know there is room to go about 1 inch higher in rear axle height because many have changed their suspension link.  So, increasing rear height by 1 inch by installing a longer shock with more travel would work fine.  Watch your chain tension throughout the travel of the suspension so it does not bind up.  The chain can get tighter at certain parts of the suspension travel.  That can be checked with the shock off and moving the suspension through it's travels.
Why would the chain bind up with increased travel? Would there be something in the way?  
AFAIK maximum chain stretch (at least when standing still!) is whenever the swingarm joint sits right between the sprockets (i.e., swingarm joint and sprocket centers are all on the same line). And I'm sure that position still happens even with the stock shock as well, so it doesn't seem like increasing travel should affect anything there..

 
 
As the suspension is compressed the chain gets tighter because of angle changes. Not worth explaining, just know it can happen. Do a search. This is why chain slack is always checked at track tech stations. A tight chain can cause the suspension to lock up and this would cause a sudden loss of traction.
 
Anyways, mostly just giving you a heads up. You may need to run a slightly looser chain if you make suspension travel changes. No biggie.

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maz20
He means that if you were to mount a longer shock, use a different rear shock link, or make any change that resulted in more rear ride height via more swingarm angle and then adjust your chain slack to the spec. recommended in the Owner's Manual, you would them likely have too little chain slack for when the swingarm moves upward and aligns the front sprocket, swingarm pivot, and rear axle. In other words, if you have more swingarm angle, the chain slack will need to be a bit more loose with the bike unloaded.
 
 
Ahh i see, so it's not as if rear travel actually affects chain tension in any way --- it just affects our "perception" of chain slack whenever we actually do need to adjust the chain.
 
So, it's not like putting in a longer shock actually requires a chain adjustment, but the next time I do have to adjust my chain (for whatever reason), I should keep in mind that having a longer shock will affect my measurements/perception and may want to go with a bit more slack than otherwise.

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YZEtc
The swingarm moving through it's arc will change the amount of slack in the chain as the swingarm moves because the distance between the sprockets changes as the swingarm moves.
This is the reason for the chain requiring a certain amount of slack.
 
The sprockets are farthest apart when the front sprocket, swingarm pivot, and rear sprocket are in alignment.
As the swingarm moves toward or away from this alignment, slack will vary.
 
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faffi
Ideally, chain slack should be measured when tension is at its highest, meaning aligned sprockets/pivot plus where the chain is at its tightest point (they are never 100% uniform though their run). You still want a little amount of slack at this point.
 
A too tight chain will affect suspension performance, cause the chain to stretch unevenly and usually kink it as well, plus - most importantly - put massive strain on the output bearing and the crankcases supporting the bearing. Deformed crankcases due to tight chains are not uncommon.

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maz20
Ideally, chain slack should be measured when tension is at its highest, meaning aligned sprockets/pivot plus where the chain is at its tightest point (they are never 100% uniform though their run). You still want a little amount of slack at this point. 
A too tight chain will affect suspension performance, cause the chain to stretch unevenly and usually kink it as well, plus - most importantly - put massive strain on the output bearing and the crankcases supporting the bearing. Deformed crankcases due to tight chains are not uncommon.[span]    [/span]
Perhaps not a very precise method, but every now and then when I adjust my chain I'll have someone else sit on the bike afterwards while I check the "loaded" chain slack. Granted, it's a bit crude in that I probably don't get the "perfect" sprockets/pivot alignment for maximum chain tension, but the chain does feel tighter nonetheless. It still has a bit of slack at this point as well (even unloaded, my chain is almost always at the 'looser' end (if not more than!) of the manual's slack range anyway). 
As far as "maximum" rear travel goes, it looks like that will depend on the shape on the shock. As the chassis gets lifted by a longer shock, the shock itself will move closer to the bottom of the upper rear shock linkage (the non-dog-bone part, forgot what it's called). However "wide" the shock itself is (well, more precisely the "spring" around the shock!), will determine how much travel it will be able to add --- that is, before it starts bumping into the unloaded bike's upper shock linkage.

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maz20
By the way, even if the rear travel does get extended too much, isn't it just a simple matter of lowering the preload for the desirable ride height anyway?

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YZEtc
While sitting still on level ground, that would be OK.
For actually riding the bike and cornering over bumps, braking, and other situations that will work the rear suspension, it may not feel so great, especially if you had to back off the spring preload an unusual amount to achieve what you wanted.
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