Carbonda fm936 Thoughts

[Colt__Seavers]

So it's not that easy like in the video?
Then I have to live with it for now and see where I end up with 42.5

If I can get a nylon washer to work, the only steps needed would be as the video describes up to 1:3, the slip the washer on, and screw it back up.

Please try and let us know what to do. Finding a 165x40 for 100€ should be very difficult so I want to keep mine.

[casual_build]

I already have my 42.5 in hand. I asked Adam if anyone had damaged the frame using that size shock.
He says "our suspension frame is design for 165x40mm rear shock. If use a 165x42.5 shock ,the rear upper seatstay may touch the seatpost." with may in bold like that.

My current plan of attack is to wait until I have the frame, put the shock on fully depressed and see what size my gap is. If its good, I will put some mastic tape on to dampen impacts.

Otherwise:
I will order the 5mm spacer and pay my capable local shop for a partial rebuild (I will give them an open air sleeve shock and handle the air sleeve maintaince). 130 USD

They would not agree to let me use the nitrogen fill pump as its a liability to have a novice assemle the piston/shaft and could explode as the it takes 600psi in there.

Also, does anyone know for sure that the rear brake mount is a post mount?

[Colt__Seavers]

A side question. I never had a fully nor a rear shock. Is it normal that I can't compress the shock with my weight, pushing it to the floor and bending over it with my torso? It's not in the frame yet. Just having the shock in my hands and trying to compress it. Unbelievable stiff. If that's normal, the forces which the frame must withstand are enormous.
Sure, 200 PSI is a lot, but compressing my Lefty fork with 180PSI is easy peasy. Don't know if I got a faulty rear shock.

[Cerps]

Not really what I wanted to read, with my 42.5mm shock waiting for the frame 
But being at around 67kg, and not particularly a jumper I guess it will be ok.
I'll put a gummy tape on the seat tube in any case, to soften any impact from the seatstays bridge.

If you're worried I'll send you a spacer to insert into the shock, free. only need to unscrew the aircan its a 15 min job...

I would love to take you up on that, what size spacer? Maybe its possible to have just a 1mm spacer so travel is still a little higher than 100mm?

Potentially, I still need to work out how a 1mm nylon washer will behave in the shock. Probaly will make it 1.50-2.00 mm to account for the 'squish' factor of nylon when a full bottom out occurs. I've not actually got my shock yet so this is all a bit theoretical. If you want me to tell you what parts you'd need then I can try.

Edit:
This could be easily solved with that 3euro https://www.bike24.com/p2331384.html part but you've got to disassemble the entire damned shock and put back in the pressurised nitrogen... Hence, the spacer has be something that can be slipped over. Not to mention, being able to change the shock by 2.5 mm is super useful for racing or riding difference conditions.

So it's not that easy like in the video?
Then I have to live with it for now and see where I end up with 42.5
I keep my eyes open for a 165x40 and might sell the other one. But not for now. Now I'll wait for the frame and will test it first.
A side question. I never had a fully nor a rear shock. Is it normal that I can't compress the shock with my weight, pushing it to the floor and bending over it with my torso? Unbelievable stiff. If that's normal, the forces which the frame must withstand are enormous.

Somehow my previous attempt to reply to this just quoted everything but my reply didn't post so I deleted it.

Unscrewing the air can and adding a spacer just changes the volume inside the air can so it just changes the compression curve.  To change stroke length you need to do a full rebuild.  I had asked both Fox and my local Fox certified shock service place and they both said the same thing.  I've also read the same thing posted on another forum that if you want to change stroke length you need to do a full rebuild.  So buying a cheap blown shock and paying $200 for a rebuild with stroke shortening at the same time is probably most cost effective.

[theirishrider]

Somehow my previous attempt to reply to this just quoted everything but my reply didn't post so I deleted it.

Unscrewing the air can and adding a spacer just changes the volume inside the air can so it just changes the compression curve.  To change stroke length you need to do a full rebuild.  I had asked both Fox and my local Fox certified shock service place and they both said the same thing.  I've also read the same thing posted on another forum that if you want to change stroke length you need to do a full rebuild.  So buying a cheap blown shock and paying $200 for a rebuild with stroke shortening at the same time is probably most cost effective.

Thanks for the info! I don't think I agree sorry, the engineering drawing suggest the small ring https://www.bike24.com/p2331384.html , simply slips over the shaft. The volume is 876 mm^3. Fox's smalled volume spacer is 3277mm^3 https://www.bike24.com/p2272994.html?q=dps%20volume .  That's 3.7x larger. If you could make a nylon spacer to a similar siez, and slip it over the shaft you don't need the aluminium one fox sells which, you are correct, does require a rebuild. I will try it when I have the shock and will report back!

[casual_build]

Somehow my previous attempt to reply to this just quoted everything but my reply didn't post so I deleted it.

Unscrewing the air can and adding a spacer just changes the volume inside the air can so it just changes the compression curve.  To change stroke length you need to do a full rebuild.  I had asked both Fox and my local Fox certified shock service place and they both said the same thing.  I've also read the same thing posted on another forum that if you want to change stroke length you need to do a full rebuild.  So buying a cheap blown shock and paying $200 for a rebuild with stroke shortening at the same time is probably most cost effective.

Thanks for the info! I don't think I agree sorry, the engineering drawing suggest the small ring https://www.bike24.com/p2331384.html , simply slips over the shaft. The volume is 876 mm^3. Fox's smalled volume spacer is 3277mm^3 https://www.bike24.com/p2272994.html?q=dps%20volume .  That's 3.7x larger. If you could make a nylon spacer to a similar siez, and slip it over the shaft you don't need the aluminium one fox sells which, you are correct, does require a rebuild. I will try it when I have the shock and will report back!

I just opened mine up, the volume spacer is probably not nylon. The alu spacer sits flush between the shaft and the volume spacer. The volum spacer is 0.2in thick where the washer sits flush and much thicker everywhere else. If you made that 0.2 area thicker, It would limit stroke and the washer would sit higher.

I think we may want to look into longboard bushings, they seem to be a similar material and we could choose the hardness. Venom makes great longboard bushings.

Edit: also longboard kingpins are 9.525mm diameter, so it would require minimal cutting

Edit #2: then put the orignal volume space over the custom cut longboard bushing, maybe upside down, to trap it

[casual_build]

Hi guys, I have to raise the rear shock questions l again.
I'm in touch with Wing from Carbonda and she said "don't use a 165x42.5 shock! The FM936 was designed for 40mm". And she had a client who jumped into a deep hole and had the rear end touching the frame, resulting in harm of the frame.
What I'm asking you guys with a 165x42.5 shock is, how much clearance do you have when there is no air in the rear shock and you use all travel? If it's just a few Millimeter, then I'm very sure that this distance might be null or even less when the flex of the frame during a jump gets added.

Maybe would be also great to know how much clearance is present when using a 165x40. Does someone have these numbers?

Did wing say that the rear shock was 165x42.5 on the bike that was damaged? Sounds like she was just to use factory spec, which is the safe side of things. I think 4mm space is enough, but I bet it varies frame to frame.

Yes she did mention it was 165x42.5mm

I asked Adam if he knew of any customers damaging the frame with a 42.5 stroke.

He said:
No customer damadges frame so far with 42.5mm stroke shock.But we are still not recommend to use that 42.5mm rear shock.

Also it's post mount rear brake

[Colt__Seavers]

Anyone riding the frame with 160mm rear disc and no adapter on PM caliper, how long the M6 bolts can/must be? Looking to get Ti bolts

[adroitrider]

He said:
No customer damadges frame so far with 42.5mm stroke shock.But we are still not recommend to use that 42.5mm rear shock.

Also it's post mount rear brake

My assumption is they get their reports from this thread. This thread is the single best source of failures and issues for this frame.

Issues are:
1. Potential out of spec spacing on the rocker (one frame)
2. Hardware is not greased (all frames)
3. Frame is not shipped with anti rattle devices (all frames)
4. Finish quality isn't a Trek or Specialized, there will be blemishes on your frame (nearly all frames)
5. Geometry posted is likely not quite accurate (all frames)

[Medico]

Riding a 42.5 shock I can tell you the chance of having isseus is minimal. Rode a bikepark!! with this bike without problems. Even cleared a jump of several meters!
Did also some enduro tracks in the Dolomites(Italien Alps) as xc biking there and it was great. Better than last years biking with a canyon nerve; better going up and way better going down.
My2c

Pics

[Colt__Seavers]

Thanks @Medico

Still missing the like function on this forum

[numberzero]

5. Geometry posted is likely not quite accurate (all frames)

What do you mean, as far as i checked, dimensions are right.
Do you have more precise informations if all frames are concerned?

[sguiom]

Hi, this is my first post here, I have followed and read the entire post, and I have finally received my FM 936 frame this week.

Concerning the shock stroke question, I have measure a length around 122 or 123 mm eye to eye for full compression (when there is contact with the seatube). So it corresponds exactly to a 42.5 mm stroke. Thus, it does not sound very safe to use such a stroke, since in case of bottom out with some mud on the seat tube or frame deformation it will hit the seat tube.

I have also measured the actual travel, it is indeed around 100 mm (vertical) for 40 mm stroke.

Moreover, frame weight in size L, normal layup is 2.095 kg including rear axle.

Finish quality is very, very good. Geometry seems accurate, in particular I have measured the front center around 800 mm which is what I am looking for. The seat tube is indeed very steep, I was hoping that the actual angle for my saddle height (800 mm on top of saddle) would allow me to use a normal seatpost, but I think I will need a setback seatpost (I like to have the nose of the saddle around 8 cm behind the BB).

[Colt__Seavers]

Oh no, I was hoping not to hear something like that. I'll measure it myself also when my frame arrives. Maybe it differs from size to size. In my opinion even 2.5mm of shock stroke length until the rear end touches the seat tube, is pretty small design wise.

[Medico]

Read this topic...please.... There are several people (incl me) riding the bike in size medium and large with a 42.5 shock without any problems.
And mudproblems? It's not a tyre clearence problem.

But I dont think there will be much difference between 100mm travel and 105/110mm...so pick a shock pricewise.