Carbonda fm936 Thoughts

[Schoobang]

The hunt for what causes the creaking goes on. I thought the linkage was fine since I couldn’t get any creaking sound from compressing it, but when rocking it sideways it creaks, and I believe pedaling creates the same kind of force. Therefore I dismounted the linkage and noticed that the upper pivot bolt shows a lot of wear after just 5km of riding. Not just visual wear but I can actually feel it. Shouldn’t all movement be handled by the bearings? I asked carbonda and they replied that I should just reinstall everything with some oil. I am not 100% convinced but I will give it a try.

[theirishrider]

The hunt for what causes the creaking goes on. I thought the linkage was fine since I couldn’t get any creaking sound from compressing it, but when rocking it sideways it creaks, and I believe pedaling creates the same kind of force. Therefore I dismounted the linkage and noticed that the upper pivot bolt shows a lot of wear after just 5km of riding. Not just visual wear but I can actually feel it. Shouldn’t all movement be handled by the bearings? I asked carbonda and they replied that I should just reinstall everything with some oil. I am not 100% convinced but I will give it a try.

I think this could be caused by the bolt being undersized compared to the Internal Diameter of the bearing. Oil would help, but then its going to act as a bushing if the bearing isn't rotating correctly. Maybe some grease would be better- would stay in place better than oil. check the bearings arn't feeling 'gritty' which would suggest premature wear.

[Schoobang]

The hunt for what causes the creaking goes on. I thought the linkage was fine since I couldn’t get any creaking sound from compressing it, but when rocking it sideways it creaks, and I believe pedaling creates the same kind of force. Therefore I dismounted the linkage and noticed that the upper pivot bolt shows a lot of wear after just 5km of riding. Not just visual wear but I can actually feel it. Shouldn’t all movement be handled by the bearings? I asked carbonda and they replied that I should just reinstall everything with some oil. I am not 100% convinced but I will give it a try.

I think this could be caused by the bolt being undersized compared to the Internal Diameter of the bearing. Oil would help, but then its going to act as a bushing if the bearing isn't rotating correctly. Maybe some grease would be better- would stay in place better than oil. check the bearings arn't feeling 'gritty' which would suggest premature wear.

It didn’t make any difference. Bearings seems fine and I used grease. Everything was installed more or less dry before. Now I am doing the bottom pivot bolt, and it looks the same. Worn down on the non-drive side and everything is dry. They must have used a lot of force to get the bolt in place the first time. It took forever to get out. To be continued...

TLDR - dismount and check linkage before riding!

[Pharaohollie]

TLDR - dismount and check linkage before riding!

I just did this. This is how the hardware looked with ZERO rides on the frame (I only cycled the rear triangle by hand a couple of times while the frame is on the workstand). The upper pivot bolt was very difficult to get out and both were bone dry.





I can't feel the wear with my finger, but if that's how it looks from brand new then that's a little worrying. I greased up the hardware, blue-loctited the bolts and torqued to spec.

[Pharaohollie]

Made a ghetto sound deadening chainstay protector. A piece of rubber interlocking floor tile cut in a wave shape, affixed to top of chainstay with a bit of double-sided tape then wrapped with mastic tape. Ugly, but functional (and weighs nothing).

[wfl3]

Well crap, I have mine 99% built now.  Guess I need to pull the wheels, cranks and shock and check out those pivots and grease as needed.

Upside is it's turning out a little lighter than expected.

[Sitar_Ned]

Made a ghetto sound deadening chainstay protector. A piece of rubber interlocking floor tile cut in a wave shape, affixed to top of chainstay with a bit of double-sided tape then wrapped with mastic tape. Ugly, but functional (and weighs nothing).

That looks like it would be the most effective sound deadener ever.

[Pharaohollie]

With 22.2mm hardware I have a small amount of play in the upper shock mount. The hardware I have seems to spec measured with cheapo calipers. I am using a spacer, for now, to take up the play, but will order a different set of 3-piece hardware to try.

[Schoobang]

With 22.2mm hardware I have a small amount of play in the upper shock mount. The hardware I have seems to spec measured with cheapo calipers. I am using a spacer, for now, to take up the play, but will order a different set of 3-piece hardware to try.

I have no play at all there, I even have to use some force to get the shock/bushing in position. In the lower mount I had to use some shims to remove play.

[Medico]

Same kind of a problem as with my lower bearing... I have play at driveside... They should had used bearings or bushings instead of mounting direct in/on the carbon frame. Better bolts would help also.

Besides these small issues its a nice frame and bikes very wrll

[Schoobang]

Good news. Half a liter of grease later and the linkage is finally silent. So is the bb! I did however just go back and forth a couple of times on the street outside my house so we’ll see if it stays silent.

Also found out that I can’t tighten the upper pivot bolt with suggested torque if I want smooth movement. Hopefully it will work anyway with some blue loctite.

[Pharaohollie]

Same kind of a problem as with my lower bearing... I have play at driveside... They should had used bearings or bushings instead of mounting direct in/on the carbon frame. Better bolts would help also.

Besides these small issues its a nice frame and bikes very wrll

Maybe I am misunderstanding something, but the lower mounts do run on bearings, no?

Did that play develop after riding or was it from new?

What model is your shock and which upper mount hardware did you buy?

[Medico]

Same kind of a problem as with my lower bearing... I have play at driveside... They should had used bearings or bushings instead of mounting direct in/on the carbon frame. Better bolts would help also.

Besides these small issues its a nice frame and bikes very wrll

Maybe I am misunderstanding something, but the lower mounts do run on bearings, no?

Did that play develop after riding or was it from new?

What model is your shock and which upper mount hardware did you buy?

They do run on bearings, but not only the part which goes through the seattube, the parts which go through the rear triangle dont have an extra sleave or bushing or so...its bare carbon.
I noticed it on my frame within the fist 1000km.

And my shock is a rs deluxe 165x42.5

Hooe this info helps

[theirishrider]

I wonder if they use poor hardware on linkages compared to NS bikes. I wonder how much NS would charge for a bearing set? probably 100 or so. might be worth reaching out to acquire a set.

[Pharaohollie]

Same kind of a problem as with my lower bearing... I have play at driveside... They should had used bearings or bushings instead of mounting direct in/on the carbon frame. Better bolts would help also.

Besides these small issues its a nice frame and bikes very wrll

Maybe I am misunderstanding something, but the lower mounts do run on bearings, no?

Did that play develop after riding or was it from new?

What model is your shock and which upper mount hardware did you buy?

They do run on bearings, but not only the part which goes through the seattube, the parts which go through the rear triangle dont have an extra sleave or bushing or so...its bare carbon.
I noticed it on my frame within the fist 1000km.

And my shock is a rs deluxe 165x42.5

Hooe this info helps

Sorry, I am still a bit confused. Do you mean this part?



If yes, then these rear triangle bolts run through bearings. The bearings sit in the rocker and are retained with circlips. See below:




There are six bearings in this frame in total. The main issue I see is that the outer torx bolt on the rear triangle binds the conical washer (I am not sure if that's the correct term) underneath it directly on the carbon. If you're not careful with how you undo these bolts (you must undo the 5mm on the opposite end while holding the torx bolt still) the conical washer/spacer under the torx bolt will dig into/start peeling the outer layer of carbon. I see the NS Synonym rocker has a recess that the bolts in this position go in, so I am not sure if it's any better on the Synonym.