Spcycle New Mold SP-R088 Carbon Road Frame

[Rajmundx]

Hello, I have a strange problem. While riding, when I'm pedaling and sitting on the saddle, there's a rhythmic knocking sound coming from somewhere—I'm not exactly sure where yet. When I stop pedaling but remain seated, it's quiet. When I stand up off the saddle and pedal, it's also quiet. The "knocking" only happens when I'm sitting and pedaling. Has anyone had a similar issue? What could be causing this sound?

[jonathanf2]

Hello, I have a strange problem. While riding, when I'm pedaling and sitting on the saddle, there's a rhythmic knocking sound coming from somewhere—I'm not exactly sure where yet. When I stop pedaling but remain seated, it's quiet. When I stand up off the saddle and pedal, it's also quiet. The "knocking" only happens when I'm sitting and pedaling. Has anyone had a similar issue? What could be causing this sound?

Check your drive side crank arm. It could be rubbing against the front derailleur. Also depending on your crankset, you might have small play on the axle. Double check the crankset to see if it's properly fitted. It might require spacers to eliminate any play.

[Rajmundx]

But why when I stood up and pedalling is silent?

[jonathanf2]

But why when I stood up and pedalling is silent?

Bike is flexing while you're pedaling. The small micro movements might be enough to cause rubbing or amplify axle play. It's just a guess, but I had similar issues on my other bikes that was coming from the crankset. Also double check if your thru axles are firmly tightened. That could be another cause for sound.

[Rajmundx]

I disassembled the entire bottom bracket and also added sleeves to the cables that run over it, in case they were knocking or something. I cleaned everything and re-lubricated it, including the pedals. I also applied paste to the seatpost clamp—let's see how it goes during tomorrow's ride.

Interestingly, while riding I slightly lifted my butt (about 1 cm) off the saddle while still pedaling, without leaning the bike to either side, and it was quiet as well.

[alfiomotrambo]

Could it be the di2 battery knocking in the seat tube area?

[Michele]

It could also be the seat clamp. Grease it according to these instructions if you haven't already...
The green stuff is grease and the black stuff is carbon paste.

[Rajmundx]

It could also be the seat clamp. Grease it according to these instructions if you haven't already...
The green stuff is grease and the black stuff is carbon paste.

I put only carbon paste on the seattube.

[Rajmundx]

Could it be the di2 battery knocking in the seat tube area?

I have LTWOO groupset but it can be. I will check today.

[Dr J]

My size 58 feels like it has the same problem that GCN had with the frame. There seems to be more movement in the head tube/handlebar than on my other bikes.

I am still trying to find what causes this. Did you all receive 2 different c-rings for the headset? Are you guys using the metal c ring?

[rcwsr]

I am still trying to find what causes this. Did you all receive 2 different c-rings for the headset? Are you guys using the metal c ring?

I have a size 58 and tried putting some force into front end like in the GCN video and I don't feel it's as bad as his. But I should record it side on. I can't remember what c-ring i used, nor if they supplied 2 different ones, I'll check my parts bin tomorrow. I know my Tideace gv201 came with 2, I used the plastic one for that after I had some issue with the metal one. Sorry for being dumb but what effect does the c-ring have on flex?

[rcwsr]

Tried to record the flex i see, hopefully these files attach correctly. The bike is in a trainer for these videos.

I get similar flex on my Condor (steel frame, full carbon fork) and my Tideace gr201. Worth noting that like in the GCN video there's a lot of tyre compression which could exaggerate how it feels and looks? I also noticed that when I compress it I can see the tiniest gap forming at the back of the headset cover spacer (can't think of the name) which would suggest the steerer is flexing slightly?

Undid stem to check and I have the metal c-ring (silver in colour) it's about 1mm thick by the looks of it, hard to tel

[alfiomotrambo]

It doesn't look like it's the same as gcn, I could be wrong, but I see you have a lot of spacers and by levering like that the carbon bends, you should try removing some spacers and see if it does it again

[Ludo]

In race car application to increase frame stiffness we used to inject expanding foam in cavities, maybe that could be an option for the steerer tube. I wonder what would be the impact.

[Bonus79]

Tried to record the flex i see, hopefully these files attach correctly. The bike is in a trainer for these videos.

I get similar flex on my Condor (steel frame, full carbon fork) and my Tideace gr201. Worth noting that like in the GCN video there's a lot of tyre compression which could exaggerate how it feels and looks? I also noticed that when I compress it I can see the tiniest gap forming at the back of the headset cover spacer (can't think of the name) which would suggest the steerer is flexing slightly?

Undid stem to check and I have the metal c-ring (silver in colour) it's about 1mm thick by the looks of it, hard to tel

Looking at the videos, it doesn't seem to flex to me...I don't even notice the gap at the back of the headset cover.

Is the C-ring you used for mounting the headset the one that came with the frame or the handlebar?

What model are the handlebars?