Disc brake adjustment...going mad!!

Yup the rotor runs fine with very little movement...flexy wheel or still a linkage issue! Would being over 16 stone have anything to do with it?!

cyfa2809":3hbrc2fh said:

Still runs free in the stand but then when ridden it rubs!

Click to expand...

^^^^^ actually that pretty much rules out any calliper pad/piston problem. when ridden, something is twisting enough to cause the pads to rub against the disc.

are spokes on rear wheel tensioned both sides?
do you have another rear wheel to try out?

get hold of a whiteboard marker pen and scribble on the disc, ride the bike so that the disc rubs but without applying rear brake - then look at the disc where the marker pen ink has been rubbed off - that will show the direction of the flex.

TBH I doubt changing seals or taking it to LBS will sort it unless the LBS can make you a stiffer new swingarm. <--- that's still my theory.

wookiee":3j00sxe4 said:

Yup the rotor runs fine with very little movement...flexy wheel or still a linkage issue! Would being over 16 stone have anything to do with it?!

Click to expand...

Could well be. I do remember some reviews of certain Marin full sus bikes and people saying that the rear end wasn't as stiff as some, but can't remember which years. I guess around 07/08.

The fact that it only does it under pedal power points to a worn linkage or flex in the frame. However, if it wad the later it would have done it from day one. The fact that you've done a fair few miles makes me think something has worn.

Well let me put it like this...

- When riding sat they is a slight rub when coasting sat none really.

- When out of the saddle putting the power down worse rub and similar when seated.

...I'm leaning (excuse the pun) towards a flex issue either the wheel or the swingarm...

Mindmap3":2t38hz7w said:

wookiee":2t38hz7w said:

Yup the rotor runs fine with very little movement...flexy wheel or still a linkage issue! Would being over 16 stone have anything to do with it?!

Click to expand...

Could well be. I do remember some reviews of certain Marin full sus bikes and people saying that the rear end wasn't as stiff as some, but can't remember which years. I guess around 07/08.

The fact that it only does it under pedal power points to a worn linkage or flex in the frame. However, if it wad the later it would have done it from day one. The fact that you've done a fair few miles makes me think something has worn.

Click to expand...

Well this is a 2008 and its been fine for the last year that I have owned it...not had any real issues with rubbing before.

But the fact that I have had a click creak for the last month is making me wonder...as I say changed out the pedals, BB, lubed the seat rails etc... so could it be the swingarm clicking and therefore is worn causing the rear wheel brake issue...

02gf74":7rl3y2b1 said:

cyfa2809":7rl3y2b1 said:

Still runs free in the stand but then when ridden it rubs!

Click to expand...

^^^^^ actually that pretty much rules out any calliper pad/piston problem. when ridden, something is twisting enough to cause the pads to rub against the disc.

are spokes on rear wheel tensioned both sides?
do you have another rear wheel to try out?

get hold of a whiteboard marker pen and scribble on the disc, ride the bike so that the disc rubs but without applying rear brake - then look at the disc where the marker pen ink has been rubbed off - that will show the direction of the flex.

TBH I doubt changing seals or taking it to LBS will sort it unless the LBS can make you a stiffer new swingarm. <--- that's still my theory.

Click to expand...

Thats a good idea with the magic marker....so where do I stand on sorting the swingarm...supposed to have a lifetime guarentee on the bearings but only for the original owner! Any one had any experience of getting this sorted for free or is it going to cost me!

I have a theory, but not enough info to verify it. Can you take some pictures of the swingarm section? More specifically the area where the rear shock connects to the swingarm itself, near the bottom link.
On the internet I don't find pictures from the right angles. Basically I need to see it from the top, as if the camera were a few inches before the seat tube, with the lens right next to the top tube really. As long as I can see the linkage, the shock mount and any other connections between both sides of the swingarm, that'll be fine.

I'm thinking that the connection between both sides of the swingarm simply isn't strong enough there.
Based on what I can tell from pictures and videos of that version of the quad-link, most of the strength in the bottom section of the swingarm appears to come from the bolt that holds the shock. In that case, any wear of the bearings would allow flex.
The top connection between both sides is merely a single tube. A single tube of that size can twist easily under the forces that the swingarm is subjected to under lean. Normally the bottom mount would prevent this from happening, but a little play there will allow quite a bit of movement near the dropouts.

Pics of the linkage/rear shock area...

When looking at the rear wheel it does appear to flex what I would say is quite a lot! When i grab it it moves maybe 5mm each way! Also dispite the wheel running true the spokes seem at differing tensions... The wheels were built then not used for some time before I started to ride on them. Is it worth a re tension of the spokes? How easy is this to do without effecting the dish of the wheell or would I just be better off taking it to the LBS?

If they are evenly un tensioned, just quarter turn each nipple all the way round. May throw it slightly out of true but not always.