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I noticed that there was some friction in the rear travel in my new aether. It felt like bearings (which at 60km usage would have been annoying). However when I took it apart it appears to be the shock bushings. If I only bolt in one and end rotate the shock you can feel the sticking. Now these have only had 120km usage so seems a bit early for them to be worn. One end is worse than the other.
This doesn't seem right to me so I'll probably change the bushes however keen to know what's likely to have caused the issue. Bike has not been washed so don't think they have got contaminated.
Is it worth lubricating them, though I thought they were self lubricating.
Shock bushings are stiff, if you can spin them (like a bearing) they are dead!
On the motorbikes I had the rear suspension ran on needle roller bearings, too bulky or heavy I guess for bike duties.
Use it lots, it may well bed in along with the shock itself.
Unless the bushing is that tight the shock takes a noticeable amount of effort to spin around the bushing, it's not likely an issue. Stiction from the shock is likely to have a far more noticeable effect on suppleness.
Just ride it, and let things bed in for a bit longer before worrying about it.
It's noticeable enough that you can feel a knock in the travel as you bounce up and down on the saddle. Not noticed while riding though.
The swing link eyelet sees a fairly large amount of rotation on the Bird bikes. Ben recommended I include an eyelet bearing kit here. Its easy to see why he did.
Ok, thanks. Presuming you fitted one which kit did you go for? Assuming they can be retrofitted to any shock.
I put an x2 in mine and got the Fox bearing kit to suit. I dont know about anything else.
Ok, thanks.
Nixie, Shock mounting hardware is meant to be snug and tight in the DU eyelet. It's normal to have to use a vice (with soft jaws) to press the hardware pin into the end of the shock. Mounting hardware would never cause a knock in the travel as you push on the bike. If the hardware was extremely worn you would get a loose rattle/play when lifting the the bike from the saddle but it would still not cause any knock through the stroke of the shock. It sounds like there's something else going on with your frame.
What make and model of shock is it? Does it make any audible squishy sounds? If so then IFP pressure might have dropped causing the damping oil to foam up and this would cause a knock in the stroke
Something like this?
Mine are still good after 7 years
@tinglesrack I thought it felt like bearings but with the shock removed there is no stiffness or step in the travel. If I install the lower end of the shock only and rotate the shock you can feel it binding. It only doesn't bind when the bolt is not done up properly. The binding occurs at around the same rotation point as I'm feeling while sat on the bike. Swapping the shock around so the upper end is lower gives a slight binding but nowhere near as bad. I was expecting the bushing to be stiff but that it would be consistently stiff, not varying as the shock rotates.
You may well be the right and I will be checking all the bearings again but at the moment it does not look like anything other than the bushings are the cause.
Shock is a CC dB coil inline.
Thanks @welshfarmer I'll take a look. It also looks like the fox set might fit (frame is the right width).
TBH I very much doubt it's the bushings from your symptoms, but, they're so quick and easy to change that since you suspect them, there's not much point in thinking about it more til you've swapped 'em. I generally don't like the parts cannon but for this it's such a cheap diagnostic.
Think I have a spare set as well. Just need a tool. Going to take all the pivots apart when I get a chance.
Just be careful if fitting a bearing in place of the bush.
I seem to remember the bushes on the CC shock I had were a different diameter to Fox bushes. Slightly smaller from memory, you'll also need the right size bush tool again a smaller diameter.
Yeah seems they did a number of sizes at different times. I have found a thread where someone has fitted the fox kit to dB inline. Will speak to TF before doing that. Hopefully it's isn't something more sinister like the frame being slightly out.
When buying a shock for my Aether 9 I asked about bearing mounts, and the opinion of TFT was that they caused more problems than they solved.
I would however give the bearings a good look. Mine were buggered in a disappointingly short time. Despite being fine quality Japanese bearings, they were not the SS Enduro Bearings that were on the spec sheet.
Had a problem with bushings that were too tight and the frame flexing laterally a few mm. It caused the shock to bind inside and scored the inner shaft. Since then I've been using nylon Bushings with a little play so the shock can move as the frame flexes.
Any alignment issues, does the shock line up nicely when only one end is attached and tightened up or do you have to push it to one side slightly to slot it into the second mount. I always change DU bushings for poly ones.
No alignment issues I can find, nor any play in the shock when off the frame. Really easy to fit the shock in this frame, much easier than my rocket was. No pushing required at all.
I've had the shock off again tonight. I've reversed the mounting direction it goes on just as easily. In this orientation the feeling is gone. Turning it back the way I've been running it the feeling returns. If I loosen the lower shock bolt so the bush is no longer taking the rotation (i.e. the hardware is rotating around the bolt) it is also not there.
My spare bushings are the wrong size so will order some and a tool tomorrow. The old eyelet seems to measure 14.6mm ID which seems odd.
Mounting hardware would never cause a knock in the travel as you push on the bike. If the hardware was extremely worn you would get a loose rattle/play when lifting the the bike from the saddle but it would still not cause any knock through the stroke of the shock. It sounds like there’s something else going on with your frame.
Undersized mounting hardware 24.39mm instead of 25.00mm caused a similar knock on my carbon mega, the hardware was machined incorrectly.
As it’s a new bike, take it back to the shop? A reputable shop will sort it for you.
Self build from frame set. Shock not supplied by frame supplier. If there is an issue with the frame I have no doubt it would be sorted based on birds reputation. There is nothing to suggest that yet though.
CC use a custom size imperial/metric bushing.
They use 1/2" hardware, but get the bushings made from 1mm thick material, hence the 14.7mm OD of the bushing.
If reversing the shock makes the issue go away then I'd be replacing the bushings, could just be a case of tolerances not playing ball (largest tolerated mounting hardware with bushing having the smallest tolerated internal diameter trading to binding).
Had a problem with bushings that were too tight and the frame flexing laterally a few mm. It caused the shock to bind inside and scored the inner shaft. Since then I’ve been using nylon Bushings with a little play so the shock can move as the frame flexes.
I had a similar issue with my DBInline on my Rocket. A few weeks after I'd had the shock serviced and paid for a new air shaft and air can out if the blue a new bushing arrived from Cotic stating there had been a small batch issue some shocks causing premature wear. I had the same problem at the next service too, with only 50 hours on the shock, new air can and shaft again. Haven't used the bike since then but if it needs another aircan and shaft next time I'll be properly peeved. Have had the frame checked for alignment by a local shop and it's completely straight with new bearings so maybe the Cane Creek shocks are just not very loerant of side loading.
Every single full sus I've owned or worked on has had a snug fitting shock so sounds like the hardware is a fraction of a milli undersized.