[Closed] Offset Bushings - must be a trade-off, reduced rear travel?

Cookeaa - you're very funny, and accurate on at least one of those points. But I think I have found some similiarly befuddled friends on this thread.

I think the second penny may have now dropped though, as you say, when the lumps of metal turn up it will all be clear no doubt.

3. Take your new, offset bushings and slot them in. Make sure the hole is facing the inwards if you wish to slacken the bike , outwards to steepen it.

thats not described wrong at all

3 - hole inwards = shorter distance between the shock mounts (each end) when bolted to the shock. The i2i of the shock doesn't change, nor does the stroke length. Travel remains *exactly* the same as before..

Therefore it slackens out the head angle...

OK, who's going to draw it to explain to those who haven't got it yet 😀 - really this is very simple 🙂

[IMG] [/IMG]
Sorry, my handwriting is shocking.

Excellent, despite being a proven idiot, I have just created my longest ever STW thread and so far learnt very little (other than about Cookea's lack of culinary skills and that velcro is for simpletons).

[i]slacker you have it the wrong way round[/i]

Thanks, I started drawing a picture and you are correct.

I was imagining inward meant the hole was moving towards the shock, when in fact the hole is the fixed point (obviously) and the bushing itself is actually moving out.

So holes inward is slacker, agreed 🙂

A and B are correct C would not happen the bushes will always tend to the shorter position shortening the effective i2i of the shock. The trade off compared to angle reducer cups which only slacken the head angle; is that the head angle is slackened as well as the bottom bracket lowered.

I was imagining inward meant the hole was moving towards the shock, when in fact the hole is the fixed point (obviously) and the bushing itself is actually moving out.

Thanks, this was the concept I've been struggling with (ie. which point is fixed).

seriously it took two pages and a diagram to understand that?
😯

no wonder it takes meetings that span days and power point presentations on how to ring fence a unicorn.

you guys are seriously lacking in the brain cell department

yeh im with spooky. stupid fixed holes not fixing holes.

*points and laughs* 😀

This thread is full of confusion, it's great.

One of the tradeoffs you have to take into account is that the minimum eye-to-eye is now shorter than before, so when bottomed out the shock is shorter than it was when bottomed out before. On some designs, there's enough clearance for this to work, on other designs hard parts will collide. My Ellsworth has tons of room to maneuvre, my Hemlock almost none. This should be obvious tbh but it almost never gets mentioned.

We were just focussing on laughing at people.

spooky you were right, porter jamies drawing is wrong.

No, he's wrong.

Seriously, i dont understand what the confusion is. Its very simple isnt it?

It is simple, but you have reversed it..
Edit unless I have misunderstood your drawing. Are the holes in your drawing concentric with the shock eyes holes or the frame holes?

This thread is full of confusion, it's great.

One of the tradeoffs you have to take into account is that the minimum eye-to-eye is now shorter than before, so [b]when bottomed out the shock is shorter than it was when bottomed out before.[/b]

Are you just adding to the confusion for the hell of it? 🙂

Seems clear enough to me...

Doh its obvious they are concentric with frame holes, you are right porterjamie, and I'm a dummy.

The holes are the frame mounting holes, the shock is still effectively fixed to the +'s.

thanks spooky. I see it now, was being king of the thickos there for a minute.

The picture would be clearer if you aligned the little circles rather than the big ones, because the shock length doesn't change. It then becomes (even more bleedingly) obvious what happens to the rest of the bike.

The picture would be clearer if you aligned the big circles rather than the little ones, because the shock length doesn't change. It then becomes (even more bleedingly) obvious what happens to the rest of the bike.

This was going to be my complaint but after a bit of consideration he has the drawing bang on, if you moved the big circles then it would be wrong. What might improve it are some lugs around the mounting holes to show the frame components moving closer together in B and further apart in C

The picture would be clearer if you aligned the big circles rather than the little ones

Impressive - you managed to quote my original version in the 5 seconds between posting it and changing it 😀

But you're right - big holes are attached to the shock, little holes to the frame. Some lugs would make it clear.

Chaps, i made several assumptions with the sketch.
The shock has big holes in which the bushes fit.
The shock actual i2i does not ever change unless you buy another shock.
The frame has small holes which the bolts go through.
The effective i2i reduces because of the offset
The effectively reduced i2i lowers the rear of the bike
This slackens the ha.
Comment earlier re slacksets, or offset headsets which slacken the ha not reducing bb height is wrong.
Slacken the ha using slackset and change nothing else, the bb HAS to get lower.

I LOVE THIS THREAD 😀

Is there a way of making it shorter?

It's full of eccentrics

I'm terribly sorry, coat etc...

[b]

when bottomed out the shock is shorter than it was when bottomed out before

no matter how much of a he-man you are I very much doubt you'll be able to do up your frame bolts enough to clamp the eccentric bushings hard enough to keep the shock in postion "c" so realistically they're not much good to steepen your head angle. You could always get longer shock and then fit offset bushings though.

oliver1981, I'm would not be so sure, there are lots of bridges held together by preload induced friction grip, ever heard of hsfg?

oliver1981, I'm would not be so sure, there are lots of bridges held together by preload induced friction grip, ever heard of hsfg?

Is this not a bush though? A component designed to reduce friction?

Ah yes, sorry didn't mean to be so confusing, I an talking about the friction between the end of the mount pin and the face of the mounting lug it is compressed up against. Not the same surface as the bushing surface. The bolt goes through the mount pin and squashes it between the lugs.

The concept of the mount pin and lug relies on friction to stop any movement of the mount pin between the lugs, it is a common misconecption that the mount pin acts in shear/bending on the mounting bolt

some people are thick as shit

I'm probably missing something fairly fundamental here but if M6 bolts give more adjustment than M8 bolts, is it not possible to get offset bushings that are the same width and diameter but use M6 bolts instead of M8 bolts?

I'm probably missing something fairly fundamental here but if M6 bolts give more adjustment than M8 bolts, is it not possible to get offset bushings that are the same width and diameter but use M6 bolts instead of M8 bolts?

the thread and hole on the frame will be m8 size so putting an m6 bolt wouldn't be an option

The bolts go onto a shaft on my bike (Mk1 nomad). I'm not sure how it works with other bikes.

So couldn't you use a shaft with the same outer diameter but a different thread size?

Well if we are really going to analyse this to death:

Instead of running them in the 3 and 9 O'clock possition, if you ran them in the 12 or 6 O'clock position you could (depending on your linkage and assuming they will stay in place) change the progression curve of your suspension. 🙂

Well if we are really going to analyse this to death:

Instead of running them in the 3 and 9 O'clock possition, if you ran them in the 12 or 6 O'clock position you could (depending on your linkage and assuming they will stay in place) change the progression curve of your suspension.

until they settle at their natural position which would be B in the diagram

I would have thought that to slacken your bike without changing the 'effective' i2i you simply put them both in the 3 o'clock position, there by shifting the whole shock to the right. On my Socom I think that would slacken the H/A and drop the BB

I would have thought that to slacken your bike without changing the 'effective' i2i you simply put them both in the 3 o'clock position, there by shifting the whole shock to the right. On my Socom I think that would slacken the H/A and drop the BB

how does your mind work 😯

until they settle at their natural position which would be B in the diagram

Hence why I said assuming they stay in place. 😉

I would have thought that to slacken your bike without changing the 'effective' i2i you simply put them both in the 3 o'clock position, there by shifting the whole shock to the right. On my Socom I think that would slacken the H/A and drop the BB

Nope, the only way to slacken the bike is to reduce the effective i2i. Moving the whole shock either direction wont have any effect as the bolts/pins will still be in the same place.

greeble, probably better than 'you're' grammar matey

Wibble is correct. And like I said before if the bolts are done up tight enough then they mount pins won't move. If you think they move we should have a chat about what happens to non offset bushes under load.