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Is it 1995 yet?

slimshady

¡Mira, una ardilla!
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jlindy86

Chimp
Feb 5, 2014
3
0
Both the Fox and Rock Shox versions have IFP's for thermal compensation - Rock Shox in the little piggy-back and Fox has it housed in the slave shaft.
 

Sandwich

Pig my fish!
Staff member
May 23, 2002
21,030
5,918
borcester rhymes
Solution: remove air shock, install coil shock.

Profit?
Haha, this is trek. Proprietary eye to eye or custom yoke.

Both the Fox and Rock Shox versions have IFP's for thermal compensation - Rock Shox in the little piggy-back and Fox has it housed in the slave shaft.
who are you and where did you come from?


my first question was: no IFP, what happens for thermal compensation? As we all know, more seals means less stiction, particularly when they are external and keep oil from leaving the shock body. There's a little known secret to getting rid of the IFP though...a bladder.
 

slimshady

¡Mira, una ardilla!
Solution: remove air shock, install coil shock.

Profit?
Behold, Occam's razor in its magnificent glory!

my first question was: no IFP, what happens for thermal compensation? As we all know, more seals means less stiction, particularly when they are external and keep oil from leaving the shock body. There's a little known secret to getting rid of the IFP though...a bladder.
Yeah, I thought their complete dismissal of the bladder solution was at least lousy. But then again, they are Trek. DRCV should have taught something to those poor guys buying their trail bikes.


EDIT: Cant't wait for their "engineers" to post to twitter laughing at our Monkey lucubrations!!!
 

Olga_icannot

Chimp
Aug 16, 2014
41
37
Seattle
EDIT: Cant't wait for their "engineers" to post to twitter laughing at our Monkey lucubrations!!!
Holy shit! I love the level of nerdery on RM but that's the first time I've had to the google the definition for a word. Lucubration = :nerd:
I can't wait to hear the explanation from Trek as to why an IFP is bad yet they ended up including one anyway to deal with thermal expansion. This feels like Trump/Russia without the vitriol.
 

jlindy86

Chimp
Feb 5, 2014
3
0
I can't wait to hear the explanation from Trek as to why an IFP is bad yet they ended up including one anyway to deal with thermal expansion.
Some type of thermal compensation is necessary to prevent blowing seals, but with the thru-shaft the IFP isn't dealing with shaft displacement every time the shock extends/compresses. Both IFP's and bladders that have to deal with shaft oil displacement inherently add some lag to the system, but that whole part can be eliminated with a thru-shaft layout.
 

Sandwich

Pig my fish!
Staff member
May 23, 2002
21,030
5,918
borcester rhymes
Some type of thermal compensation is necessary to prevent blowing seals, but with the thru-shaft the IFP isn't dealing with shaft displacement every time the shock extends/compresses. Both IFP's and bladders that have to deal with shaft oil displacement inherently add some lag to the system, but that whole part can be eliminated with a thru-shaft layout.
honest question: how does a bladder, which doesn't slide but rather compresses, create lag/friction/hysteresis?


I won't deny that the idea has merit, but knowing trek it will only be available on a few models for a few years and won't be cross compatible with anything else on the market.
 

Olga_icannot

Chimp
Aug 16, 2014
41
37
Seattle
Some type of thermal compensation is necessary to prevent blowing seals, but with the thru-shaft the IFP isn't dealing with shaft displacement every time the shock extends/compresses. Both IFP's and bladders that have to deal with shaft oil displacement inherently add some lag to the system, but that whole part can be eliminated with a thru-shaft layout.
Yup, I understand the basics. And I'm sure the Trek guys gave us the USA Today media version of how it works but from the interview he seems to make a blanket statement as to how IFPs are bad and then glosses over the fact that the shock has one anyways. Admittedly the IFP in their new shock doesn't move much (oil doesn't expand much when heated) or often but it still has one, it's still subject to the same manufacturing tolerance, wear, complexity, and service restriction (I don't yet have my own nitrogen tank to recharge the IFP if I try to service the shock myself).

I'm going to date myself here a bit and go ahead and admit that I owned several iterations of the AMP Research frame in the early/mid '90's with a through shaft coil shock (with titanium spring!). That thing constantly leaked from its ass end.


Cool story, eh?
 
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jlindy86

Chimp
Feb 5, 2014
3
0
honest question: how does a bladder, which doesn't slide but rather compresses, create lag/friction/hysteresis?
Bladders do avoid the IFP seal friction, but in the case of the design you pictured, it still requires pushing fluid through a tube/hose in and out of the reservoir. Fluid friction occurs that you can't really do anything to easily tune/adjust. Controlling damping via that displaced fluid (ie remote/base valves) works off of a relatively small amount of fluid, compared to the amount of oil being forced through the mid-piston on a thru-shaft shock. The real benefit to thru-shaft shocks isn't removing the IFP seal friction, but really the piston working against a solid column of fluid that isn't supported by a spring (IFP/bladder). The lack of oil displacement also allows for lower pressurization and seal friction...granted you're adding a seal for the slave shaft so the net friction change is minimal.
Interesting article that's a bit dated from '02, but still relevant - http://www.f1technical.net/features/10660
 

trib

not worthy of a Rux.
Jun 22, 2009
1,456
388
I can see the benefits of this system, but am rather frustrated by the lack of true innovation in the suspension industry at the moment.

The issues the "Reaktiv" system is trying to solve could be completely negated if suspension companies used some kind of high tech elastic polymer to control rebound and compression.
 

toodles

ridiculously corgi proportioned
Aug 24, 2004
5,479
4,719
Australia
(oil doesn't expand much when heated)
Wait - what? Yeah it does - it expands something like 4 times more than water does. We had massive issues with it when we converted a water tube boiler to a thermal oil heater for a work project a few years back.

As an aside, I know the extra shaft seal might seem like twice as many opportunities to leak but I wonder if the through shaft design will prevent twisting and align the shaft better through the seals.
 

Olga_icannot

Chimp
Aug 16, 2014
41
37
Seattle
Wait - what? Yeah it does - it expands something like 4 times more than water does.
Oh, who knew? RM educating me again. I suppose I was thinking that most of the IFP movement is due to displaced oil, not thermal expansion. But I could easily be wrong about that too.
 

toodles

ridiculously corgi proportioned
Aug 24, 2004
5,479
4,719
Australia
Oh, who knew? RM educating me again. I suppose I was thinking that most of the IFP movement is due to displaced oil, not thermal expansion. But I could easily be wrong about that too.
Nah you're right, the shaft displacement would be much, much more than thermal expansion. But I still wouldn't want to heat up a hydro-locked damper. Apparently it has a mechanism to deal with thermal expansion anyway.
 

troy

Turbo Monkey
Dec 3, 2008
1,006
739
So... 6pot calipers from Hope are back, so is the Pro Deluxe shock. Still waiting for the URT suspension to come back to its glory (with some BOOST "technology" ofc):nope::nope::nope:
 

Flo33

Turbo Monkey
Mar 3, 2015
2,057
1,298
Styria
So if finally a bike with through shaft damping technology, speed balanced geometry, supermegahyperboost and automatic telescope seat post emerges from the Atlantic ocean's capital, I will spend serious money again.

Plus: Bonuses for 32.7" wheels can be obtained.

It's your turn, lizards.