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shortest 2.75 stroke shock?

dante

Unabomber
Feb 13, 2004
8,807
9
looking for classic NE singletrack
Or perhaps keep the same amount of travel but lower the BB height and slacken the HA?
You know if you shorten the shock i2i without reducing the travel, there's a relatively good chance you'll have either the frame hitting itself or the tire hitting the seat tube or saddle, right? Not saying that it hasn't been done before (drilled 2003/2004 IH SGS frames and the 2005 IH Kumicho to name 2), but even then there was usually some nice tire rub on the seat tube or frame to frame contact.

Optimally you'd want to go from 8.75x2.75 to 8.5x2.5 and deal with the slightly reduced travel. But otherwise Craig at Avalanche would probably be able to set you up if anybody could...
 

Sonic Reducer

Monkey
Mar 19, 2006
500
0
seattle worshington
it is my 05 demo 8. I am not having any luck selling it so am thinking about keeping it and trying something new while upgrading from the swinger 4 which although usable is not really optimum. as far as I know, an 8.5x2.5 shock will work on it. its not like its a super tall bike to begin with at 14.4" BB height, but I would like to get it to around 64* HT. I have cycled the frame without a shock and I think I may be able to get away with something shorter. if I cannot find any 2.75 shock I guess I will just go with a 8.5x2.5.
 

Inclag

Turbo Monkey
Sep 9, 2001
2,750
439
MA
it is my 05 demo 8. I am not having any luck selling it so am thinking about keeping it and trying something new while upgrading from the swinger 4 which although usable is not really optimum. as far as I know, an 8.5x2.5 shock will work on it. its not like its a super tall bike to begin with at 14.4" BB height, but I would like to get it to around 64* HT. I have cycled the frame without a shock and I think I may be able to get away with something shorter. if I cannot find any 2.75 shock I guess I will just go with a 8.5x2.5.
Why not just send the shock to Avalanche for the custom shimmed damper conversion, and see if they can reduce the stroke by .25" for the lower BB and slacker HA?
 

time-bomb

Monkey
May 2, 2008
957
21
right here -> .
You know if you shorten the shock i2i without reducing the travel, there's a relatively good chance you'll have either the frame hitting itself or the tire hitting the seat tube or saddle, right? Not saying that it hasn't been done before (drilled 2003/2004 IH SGS frames and the 2005 IH Kumicho to name 2), but even then there was usually some nice tire rub on the seat tube or frame to frame contact.

Optimally you'd want to go from 8.75x2.75 to 8.5x2.5 and deal with the slightly reduced travel. But otherwise Craig at Avalanche would probably be able to set you up if anybody could...
this really just depends on the frame. my bike is designed to run a 9.5x3.0 and i had the shock modified to 9.15x3.0 and there is no with tire contact or links hitting the frame. i would definitely encourage anyone that is considering doing something like this to check with the bike mfg'r before they do this to avoid the potential issues you have brought up.

Sonic Reducer - call Specialized, if they can't help then try someone at PUSH or Craig at Avalanche. There is a good chance they would know this since your frame is pretty popular.

Another option to consider, although its less popular amongst DH racers, is to just run a 24" wheel on the back. It will slacken your HA but there is a tendency for the rear wheel to hang up a bit more on larger objects. On the plus side you could run an 8.75x2.75 shock and keep all your travel and since that is a common size you will have no problem finding a replacement for your 4-way.
 

DirtyMike

Turbo Fluffer
Aug 8, 2005
14,437
1,017
My own world inside my head
Ok, on the demo, if you reduce the I2I on the shock, you will have to go with a shorter stroke shock, or you will have frame contact, possible breakage.

Time bomb has probably the best suggestion for what your looking to do. 24 in rear wheel, and send your shock to Avy for a nice custom shim stack conversion, you wont be dissapointed.

Another question....Why are you loking to get your HTA that low?
 

Sonic Reducer

Monkey
Mar 19, 2006
500
0
seattle worshington
just a wild hair i guess. how much would it really slack it out lowering the shock 1/4"?
don't want to run a 24" wheel.
i wonder about lowering a shock a little bit myself with spacers. I have done it to a couple motorcycle forks which are pretty simple, you just shim the damper rod and cut the spring equal amounts. not having seen the inside of an MTB shock I'm not sure wether or not it would be.
 
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DirtyMike

Turbo Fluffer
Aug 8, 2005
14,437
1,017
My own world inside my head
Not sure, maybe one of the Suspension gurus on the site could run it through one of their cool frame building programs to give you an idea, but I will tell you, it will effect the way the suspension reacts in ways you probably dont want it to.
 

bushrider

Monkey
Jul 4, 2006
146
0
NYC
running a 8.5 X 2.5 or less than 8.75 X 2.75 will compromise the suspension performance of the demo significantly.
The Demo is pretty progressive anything that shortens the shock length will compromise the suspension as it will sag further into the stroke where the suspension rate ramps up heavily.

For example cave dweller ran a shorter shock with less stroke on his turner DHR (also very progressive).This gave him the geo he wanted but the suspension performance was definitely compromised.

Shorter shocks work pretty well on most simple single pivot designs or with designs that are very linear (assuming there are no clearance issues). My Foes Mono has an adjustable rod end on the shock which changes geo without changing the travel. This works well on the mono as the frames suspension rate is pretty linear and the progression comes from the shock and is adjustable.

I'm pretty sure avalanche cannot make a shock which is 2.75 and less than 8.75. They can reduce the stroke and eye to eye by the same amount easily. Doing that and possibly cutting down the bottom out bumper to squeeze out a little more travel might be the best bet.

Talk to Avalanche about your options, if Craig thinks its a viable idea I'm sure it will workout well.

Running a flat bar and low stack height combined with a bigger front tire and the forks raked out as much as possible will help slack out the geo and will keep the handlebars at roughly the same height. Increasing the front end height 1" will raise the BB roughly 1/3".

Avalanche forks might help. They have more rake/offset which translates to more stability and IMO a similar effect on handling to a slacker HA.