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Trunnion mount adapters...why not?

ChrisRobin

Turbo Monkey
Jan 30, 2002
3,346
190
Vancouver
Aside from the fact the eye-to-eye length and stroke would be all wonky, is there a reason why no one's really come up with a trunnion to regular eyelet adapter??
 

Jm_

sled dog's bollocks
Jan 14, 2002
18,855
9,560
AK
Don't take this the wrong way, we've all been down the proprietary road at some point, but the vast majority of people buying the proprietary stuff don't know any better and won't care. When the shock stops working, they'll let it sit in a corner, just accept how it works, or sell it and buy a new one. The last things on their mind will be suspension performance or being able to service what they have. That's just the vast majority of bikes that are sold. That's why the some of the smaller companies gained so much foothold, for people that know exactly what they want. Not quite as true now as it was 10-15 years ago, but still to some degree.

Bikeyoke does the yokes on the specialized stuff.
 

buckoW

Turbo Monkey
Mar 1, 2007
3,777
4,700
Champery, Switzerland
Don't take this the wrong way, we've all been down the proprietary road at some point, but the vast majority of people buying the proprietary stuff don't know any better and won't care. When the shock stops working, they'll let it sit in a corner, just accept how it works, or sell it and buy a new one. The last things on their mind will be suspension performance or being able to service what they have. That's just the vast majority of bikes that are sold. That's why the some of the smaller companies gained so much foothold, for people that know exactly what they want. Not quite as true now as it was 10-15 years ago, but still to some degree.

Bikeyoke does the yokes on the specialized stuff.
Wut
 

Floor Tom

Monkey
Sep 28, 2009
288
55
New Zealand
Don't take this the wrong way, we've all been down the proprietary road at some point, but the vast majority of people buying the proprietary stuff don't know any better and won't care. When the shock stops working, they'll let it sit in a corner, just accept how it works, or sell it and buy a new one. The last things on their mind will be suspension performance or being able to service what they have. That's just the vast majority of bikes that are sold. That's why the some of the smaller companies gained so much foothold, for people that know exactly what they want. Not quite as true now as it was 10-15 years ago, but still to some degree.

Bikeyoke does the yokes on the specialized stuff.
Huh? Trunnion mount is far from proprietary, it seems to be on a lot of new bikes now.
 

hitar_potar

Monkey
Sep 23, 2011
173
6
Ruse, Bulgaria
I don’t understand the OP’s question that created the thread? OP, what exactly do you mean? Adapter for what? To put metric shock on a trunnion-metric frame? Vice-versa? A non-metric shock on a trunnion-metric frame? Only mode/tinker regarding old and new shocks and frames i’ve read about is on a 2020 Kenevo - someone put a 230x70mm non-metric shock on the frame so it now does around 200mm. Might have read it even here... :)
 
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Floor Tom

Monkey
Sep 28, 2009
288
55
New Zealand
Yeah, that would work, the trek trunnion shocks are super long so you can fit a standard metric shock in there as well, I had an x2 in my slash.
But for most metric shock bikes there would be no point since you aren't going to get the stroke required if you change a trunnion shock out for a standard one.
 

buckoW

Turbo Monkey
Mar 1, 2007
3,777
4,700
Champery, Switzerland
Yeah, that would work, the trek trunnion shocks are super long so you can fit a standard metric shock in there as well, I had an x2 in my slash.
But for most metric shock bikes there would be no point since you aren't going to get the stroke required if you change a trunnion shock out for a standard one.
Yes, it usually reduces the travel around 2cm. My 170mm Ransom with a 200x57 imperial shock has around 150 of travel.

Rock Shox no longer offered imperial shocks from one year to the next so that’s the only reason everyone moved so quickly to metric/trunion.
 

Floor Tom

Monkey
Sep 28, 2009
288
55
New Zealand
I assume it also drops the bb by around 10mm, maybe slightly more?
I can see how that might make for a fun bike but it seems to be quite a niche implementation for people who want to quite drastically alert their bikes geometry. Not really something that most people are likely to want to do. Also it requires an imperial shock which from what you say are becoming harder to get hold of (I have no experience, all my current bikes use metric sizing).
So it seems like the adaptors the OP is asking about are available, but outside of quite a radical change, or on trek bikes, are not really useful.
 

hitar_potar

Monkey
Sep 23, 2011
173
6
Ruse, Bulgaria
I was interested in some sort of adaptation of a trunnion shock to an imperial-shock frame: a frame using originally a 222x70 shock, and a 225x70/75 trunnion shock. No adapters to use, just check whether the shock’s trunnion end will fit in the frame (in the rocker arm?) and if the bolts required for the trunnion mounting will go through the rocker. :) Wanted to see if anyone’s done that cause the price for me being the guinea pig would be 460 euros (before shipping, speciffic shock). :)
 

jonKranked

Detective Dookie
Nov 10, 2005
85,573
24,191
media blackout
I dunno anything about it, but here's this.

And for the record, I'm not mad about trunnion. I would have happily bought a Privateer frame if it had been available.

https://www.dirtlabs.com/products/copy-of-trek-trunnion-mount-adapter-kit

note the bending disclaimer.

i'll post a pic later, but my xprexo has a wide mount on the swingarm for some reason, and i've bent a number of steel mounting bolts over the years (thankfully they are cheap and i was able to source them through mcmaster).
 

buckoW

Turbo Monkey
Mar 1, 2007
3,777
4,700
Champery, Switzerland
I assume it also drops the bb by around 10mm, maybe slightly more?
I can see how that might make for a fun bike but it seems to be quite a niche implementation for people who want to quite drastically alert their bikes geometry. Not really something that most people are likely to want to do. Also it requires an imperial shock which from what you say are becoming harder to get hold of (I have no experience, all my current bikes use metric sizing).
So it seems like the adaptors the OP is asking about are available, but outside of quite a radical change, or on trek bikes, are not really useful.
Yes. The bb height chips on the link make up for the difference IF you run 27 wheels. The 222 i2i and 205 i2i shocks are the only ones I’ve fitted to metric bikes but they had bb height adjusters so I could get away with it. However, Trunion shocks have unnecessary side loading on the shock bushings so I wouldn’t try and put one on a bike that was designed for a normal eyelet. That might be a downgrade.... Getting more travel out of the rear could be the only advantage imo.
 

ChrisRobin

Turbo Monkey
Jan 30, 2002
3,346
190
Vancouver
That's interesting...

But I think overall it'll be next to impossible to get a regular sized shock to fit a trunnion mount frame, even with funny adapters.

I have an Avalanche Woodie (9.5x3.0) that doesn't fit anything I have and needs to be repaired (rebound knob broke). I think in order for it to fit a frame that uses trunnion 225x75 shock, I'd have to get Craig to resize it to 9.0 x 3.0, then find trunnion adapters. Even then, I'd still have to get an offset bushing for the regular eyelet end to match the 225mm length. Overall, too expensive of an experiment.
 
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Jm_

sled dog's bollocks
Jan 14, 2002
18,855
9,560
AK
That's great, because I'd rather gave my energy chews getting dirt, dust, dog-poo and everything else on them rather than in a gas-tank (stem) bag...