Why can't I...? (Offset Bushing Content)

It's not actually the bushing that is offset, the metal sleeve that slides into the DU bushing (usually red coated on the inside) is called a reducer - and that has the offset hole drilled into it.

Anyway, there's no reason you can't have your own done. Stainless is probably fine for material choice, you just have to make sure the outer surface is very smooth (because it has to rotate inside the bushing, if it is rough it will wear it away quickly).

Also, the reducer is clamped in the frame and should not move, as it is the shock (and DU bushing) that rotates around it. If there is inadequate clamping force then the reducer *could* rotate, but obviously you don't want that as it will change your geometry from what you intended.

I made this from 7075 aluminium. It is for a 6 mm bolt on a trail bike, 1.5 mm offset. I have made regular reducers from the same material before and they were fine. The surface looks somewhat rougher on the pic than it is.

Just buy a frame that does what you expect it to do.

Faster, cheaper, less hassle. Unless you really got to do it, then be sure to keep us up to date with your findings.

It completely depends on the bike how much change you achieve with that offset hardware.
I think you can test the change to static geometry by just backing off the preload ring on your shock that few millimeters from the point where it is not preloading the spring at all.

And I would recommend to only use that offset hardware on shock mounts that do not rotate much, because you could run into trouble with shock axle/hardware rotating under high load.

Me and my buddies have a few of them that a local guy made. Not a problem for us.

Lowering your bottom bracket will slacken your HA. Sorry, thats how it works. You shortening your shocks I2I so your bike will behave like it its riding lower in its travel which in turn slackens the bike and lowers the BB height. One possible way to maybe get around it is if the inserts slackened it about .5 degrees and then you swapped your fork or headset for one thats about 10mm lower. Then they would cancel each other out and you would have a lower BB height..

Another problem you could run into is some bikes like VPP and such are designed to ride in a certain sweet spot and using these could possible throw that off but I doubt it.

Last possible problem is it would make it more likely that your tire could hit your seat tube on bottom out. Some frames have the problem anyway but if yours didn't but was really close then this could give it that extra room to contact it.

Just things to think about. We use them and like them so I am not trying to talk you out of it but just be aware of the affects

Wa-Aw said:

I understand, I used the wrong terminology. Would I have to fabricate a metal sleeve too or can bolts this size (can't remember the std shock eyelet size off hand) be found by people savvy in this industry?

Is there a chart or common knowledge as to how much offeset makes x difference on the bikes geometry or would this also be unique to each bike due to linkages etc?


Say I wanted to lower the BB height of a bike but keep the head angle relatively constant. Would getting offset shock hardware then steepening the bike's HA achieve that or would these adjustments cancel each other out?

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using your bikes avg leverage ratio you can determine the changes. if your bike has a 3:1 avg ratio and you shorten the i2i of your shock (which is what the reducers ultimately do) 3mm you've moved your rear wheel 9mm into its travel before even getting on it. remove air if you have an air shock and move it 3mm into travel or back off the preload collar and compress your coil shock to get it 3mm into travel and you can take all the measurements you want.

offset reducers + shorter axle to crown would lower your bb without effecting HA too much. again, you'd need to take some measurements to determine how much of each you'd need to get where you want.

StabprimoMonkee said:

Just buy a frame that does what you expect it to do.

Faster, cheaper, less hassle. Unless you really got to do it, then be sure to keep us up to date with your findings.

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cheaper? I'm pretty sure offset bushings cost ~20 bucks max. Find me a frame that does what I want it to do for 20 bucks and sign me up for 10 of them.

I made a set for a friend years ago for a giant frame that had a odd length shock, no new replacement was right.

He still rides it with no problems.

StabprimoMonkee said:

Just buy a frame that does what you expect it to do.

Faster, cheaper, less hassle. Unless you really got to do it, then be sure to keep us up to date with your findings.

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What?

Making 2 sets of offset reducers would probably take me maybe a half hour on the lathe if I didn't have to go scrounging around for tooling.

It can also be made out of scrap. You could probably go to any machine shop and just get some rem stock of round aluminum stock just to make a trial run with, or even something better like 316 or A2 tool steel if you were lucky and wanted a permanent set. Buying this material would probably be ~$30 USD or less if you know where to look.

I don't know about you, but for me making and installing a couple bushings is a ****load less hassle than sourcing, buying, shipping, and building up, and dialing in a new frame and suspension. Having someone else make them is even less hassle.

Fail.



I've had offset bushings work with good success before, and seen lots of other people using them. Couple things to be aware of:

- Check the shock/frame for possible interference if you were to shift the shock forward a few mm. Meaning, the shock collar or the bridge/body of the shock isn't going to contact the frame or linkage plates by it now being closer. Rotate it through the travel after you're done to check.
- Be very precise in measuring the length and diameter of the cylinder. The length has to be adequate so the frame/linkage plates are pinching it and holding it firmly in place so it doesn't rotate with the DU bushing and stays with the frame. On the same note, give the shock with the DU bushing installed to your machinist, and tell them you want the cylinder to be a tight slip-fit to a loose press-fit in the DU. This will guarantee the fit, rotational freedom, and longevity of the bushing.


I just installed one of these http://shop.synergyseals.com/product.sc?productId=18&categoryId=6 on my girlfriends KTM 200 to lower the bike a bit for her. Same concept. Sleeve with a hex cutout installed in place of the stock bearing, and an adjustable block that can be clocked in 6 different ways. Sorta flip-flopped though, because the bushing is part of the frame and the shock has a yoke on the end that clamps around the frame extrusion. Something like this would be cool on a DH bike to play with geo and leverage, but I don't think the hardware or the clearances of modern shocks would allow that.

I just shortened the shock on my '09 Remedy by 1/8"... went from the stock rp23 at 8" i-to-i to a Vivid Coil at 7.875. It changed the HA by about 1/2 degree (sitting right at 66 now) and bb height change isn't noticeable, I don't have the same tires on so it's hard to tell. BB is sitting at around 13 3/4" - 13 7/8" with 2.4 TK front/2.3 Clutch SX rear tire. This shock will also be able to run more sag than the rp, I'd guess the dynamic changes in geo will be more noticeable than the small static change provided by the 1/8" shorter i-to-i.

Does anyone know a company that manufactures shock offset bushings in the United States? The only company I could find that makes them is Burgtec and it gets a little pricy with the exchange rate. I don't really want to deal with a machine shop.

Thanks

Sweet! Thanks.

Stainless steel is a b1tch to machine

Sandwich said:

http://www.ebay.com/itm/Offset-Shock-bushings-Mounting-Hardware-Mount-kit-All-frames-Proshox-/300611150162

I could have sworn there was another guy, in the US, that basically did them out of a machine shop like this.

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19 bucks is a good price. but despite all the detail on his ebay page, i can't find what offset, or range of offset, he provides. ?

edit: never mind. I hired a team of detectives and eventually we found it in the small print:

"Offset (deafult is maximum but can be done: 1, 2, 3 mm (3mm only for 6mm bolt)"

StabprimoMonkee said:

Just buy a frame that does what you expect it to do.

Faster, cheaper, less hassle. Unless you really got to do it, then be sure to keep us up to date with your findings.

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If frames are all that cheap, can you buy me one too!

Any machine shop can make them. Just use 3 series stainless, or a bronze alloy.

Easy. Would take me less than an hour to make up a set if I had zero set up to start.

atrokz said:

Any machine shop can make them. Just use 3 series stainless, or a bronze alloy.

Easy. Would take me less than an hour to make up a set if I had zero set up to start.

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as an experiment for my bike i made one with 1/2" round 6000 series aluminum stock. put it on the lathe to size it down a bit, cut to length, drill the hole and polish it up.

Wa-Aw said:

I heard mm's can make a huge difference in linkages...

Do you think it placing offset bushing on a side to side offset rather than up and down offset could affect this substantially? Say if I wanted the bike to be more progressive I could but a right offsett on the bottom and a left offset at the top?

Bushings rotating might be an issue though.

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mm's are claimed to make a substantial difference when you are moving pivots around, not if you are sliding up and down the leverage curve. All you can do with offset bushings is affect where the shock stroke starts and ends along the leverage curve. You are not changing pivot position, so axle path is the same and instant-center migration path (for multi-link frames) is also the same. It's as if you were able to run more sag without making the suspension mushy.

If frames are all that cheap, can you buy me one too!

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Between the hassle and new headset it would easily cost 300$ to get the mod done.

Depends on where you are and what are the resources at your disposal. That might get me considering selling the frame and buying one that does what I want.