SZZS specific CEF50-main thread (initial builds and troubleshooting related only)

[ssl]

It was the main pivot bolt that fits into the rocker arm near the top shock mount. It was 8 mm too short amazingly.
View attachment 136368

I eventually broke the mating bolt mid-ride but was able to ride it back to my truck with no damage, but marred up the paint a little at the pivot joints of the stays due to lopsided slack creating friction points. So, I found out the correct size and had both Ti pin/bolt custom made, in a weekend luckily.

No problems since (7 of 8 months). SZZS eventually sent a warranty replacement pivot pin/bolt assembly that I've kept on hand as a spare. Just poor quality control and I didn't have reason to pull the linkage bolts to check them all out prior.

I posted the whole story in our thread last June or July for pics and further details.

Do you have screw sizes specs and even better where to order them as quality of screws is bad, even with new shipped frames (got mine 2 weeks ago) and threads are already gone on some from working on them.

 

[ssl]

Since you're in the US, I used Huk-Tek: engineered bike hardware out of Michigan.
The owner is Derrick.

View attachment 148247
Contact in Facebook or email:
View attachment 148246

He modified the mating bolts with thicker heads and larger threads to match the custom pins (thru-bolt) so my specs are specific to the custom hardware. I went with Ti, super expensive due the pin cost which was most of metal used.
View attachment 148248
I recommend keeping the OEM AL pins and just having Derrick match them to Aluminum or steel mating bolts (don't know if he'll do steel, Plus, Al might be a better choice with existing Al pins).

I recommend a good digital caliper to measure accurately. Just work with Derrick directly for sizing specs needed. Good Luck!

Do you have size specs for all of them?

 

[TCFlowClyde]

Do you have size specs for all of them?

Both the pins and mating screws custom specs to beef them up. So both have bigger screw beds and threads.

I recommend just using the same lengths and thread size for the mating bolts and keep your Al pins from SZZS. You'll save a lot of cash that way and they'll be very strong.

 

[ssl]

Both the pins and mating screws custom specs to beef them up. So both have bigger screw beds and threads.

I recommend just using the same lengths and thread size for the mating bolts and keep your Al pins from SZZS. You'll save a lot of cash that way and they'll be very strong.

So you don't have exact specs? As have to remove all to see and measure

 

[TommyR]

For what it’s worth, I’ll be removing and measuring all of the suspension hardware once my frame arrives. I’ll be sure to share it here once I do. I have some Ti shock mounting bolts, but need the frame to verify sizing.

 

[ssl]

For what it’s worth, I’ll be removing and measuring all of the suspension hardware once my frame arrives. I’ll be sure to share it here once I do. I have some Ti shock mounting bolts, but need the frame to verify sizing.

Ordered shock once on Ali.....33mm and 38mm as people said perfect fit while motor and rest of the frame seems to be "custom" sizes

 

[TCFlowClyde]

So you don't have exact specs? As have to remove all to see and measure

So you don't have exact specs? As have to remove all to see and measure

I don't off hand because it was a year ago. Unless you're planning on using custom pins, they'll be different diameter sizing than OEM, so my bigger custom hardware won't match up to the smaller bolt thickness on the CEF50.

 

[ssl]

I don't off hand because it was a year ago. Unless you're planning on using custom pins, they'll be different diameter sizing than OEM, so my bigger custom hardware won't match up to the smaller bolt thickness on the CEF50.

But they fit well on the frame no?

 

[TCFlowClyde]

But they fit well on the frame no?

Yes, perfect fit in the frame...no slack. It's the thread bed of the pins that are a larger bore, so the mating screw/bolt shank could be made thicker. The outer diameter of the pin and the thread pattern is the same as stock SZZS.

 

[ssl]

Yes, perfect fit in the frame...no slack. It's the thread bed of the pins that are a larger bore, so the mating screw/bolt shank could be made thicker. The outer diameter of the pin and the thread pattern is the same as stock SZZS.

Excellent sonof you can put specs of each would be great so can try get them made in Europe. You provide is US based? He ships worldwide?

 

[TCFlowClyde]

Honestly, I don't know if he ships international...I'd guess probably yes. Contact him via email or Facebook and just tell him what you want. He'll help you with your custom measurements. If you do, then just list your measurements for others on this thread.

Good luck!

 

[Wix]

Cześć wszystkim. Szukałem, ale nie znalazłem żadnych informacji na ten temat, więc proszę powiedzcie mi, jeśli wiecie:

Jaka jest rzeczywista wysokość bb? Producent mówi, że 360mm, prawda?

Is that any space for ad offset bushing or longer shock? Many riders here suggested longer shock for longer travel and mullet conversion, but trully i see almost zero place for rear triangle bending - collision between chainstay droputs / main pivot axle and motor mount.

 

[TCFlowClyde]

Cześć wszystkim. Szukałem, ale nie znalazłem żadnych informacji na ten temat, więc proszę powiedzcie mi, jeśli wiecie:

Jaka jest rzeczywista wysokość bb? Producent mówi, że 360mm, prawda?

Is that any space for ad offset bushing or longer shock? Many riders here suggested longer shock for longer travel and mullet conversion, but trully i see almost zero place for rear triangle bending - collision between chainstay droputs / main pivot axle and motor mount.

I and a handful of others are using the 210 x 55 setup. I think most are mullet/mixed.

I don't think anyone has gone up to the next longer shock size of a 230 x 57.5/60 with an offset bushing. I think that would really be pushing the kinematics of the frame design. The 55 stroke seems to be the limits with the 210 eye-to-eye length.

But that said, you could try it and just mount it statically first and see what happens. If an air shock, deflate it completely and see how it close it gets to rocket arm joint before it rubs.

With my 210 x 55, I could only put in a standard piece of printer paper in without indentation....so far so good after a year and half with only small jumps/drops.

 

[Wix]

Thanks, but next step is 216x63

 

[TCFlowClyde]

Thanks, but next step is 216x63

Sure, but same response....just less risky. No one has tried a 216 x 63 and posted here, however if it works then let everyone else know.Also, technically isn't the next step up the 216 x 57?
Additionally, I thought about the 210 x 57 but figured the 57 stroke would be too much...that might be the logical max?

 

[Wix]

Ok but all at all any shock cant be use if the swingarm has no space and get contact with frame. I have one guy in Poland who built cef and I will check. Anyway this bike as mullet without.geometry conversion is not a good way IMO. With small wheel on the back geometry is.too much radical.

 

[TCFlowClyde]

Anyway this bike as mullet without.geometry conversion is not a good way IMO. With small wheel on the back geometry is.too much radical.

Sure, not having a geo flip-chip is less than ideal, but I suspect the kinematics difference is marginal without one. Some very experienced CEF50 riders are using mixed wheel successfully. They probably were already riding mixed on other bikes and desire a little more agility. This can feel twitchy in handling to those using straight 29ers. It's personal preference.

Others can chime in with mixed to report their experience.

Also, it sounds like the CEF50 might not meet your needs? What you see, is what is being offered from SZZS. Maybe a future version can be designed with a flip-chip and bigger Enduro travel like 180/170, but I think it's original intent was a 29er 170/150 trail frame that others including myself have been able to push a little more successfully so far.

 

[mike_kelly]

New Website. Not completely finished but good news.

Carbon Fiber Bicycle, Bike Frame Manufacturers & Factory & Supplier | ZSZT

OEM & ODM Services For All Kinds Of Carbon Fiber Bicycles Frame

www.szzsbike.com

 

[TCFlowClyde]

New Website. Not completely finished but good news.

Carbon Fiber Bicycle, Bike Frame Manufacturers & Factory & Supplier | ZSZT

OEM & ODM Services For All Kinds Of Carbon Fiber Bicycles Frame

www.szzsbike.com

Relatedly, rumor has it that SZZS is creating a CEF50 frame for the DJI Anivox drive system for the late 2026/early 2027.

But, I like the Bafang M830-75Nm...however I wouldn't mind a firmware update:
1) 5-10% turbo shutdown battery reserve,
2) an actual high Nm walk-mode,
3) maybe an 85Nm full boost turbo 60 sec mode?

 

[mike_kelly]

I am sure the DJI is going to be an expensive motor. Frankly the M820 does everything I had hoped for. I love this bike. The original promise of a short burst mode would have been nice tho.

 

[TCFlowClyde]

I am sure the DJI is going to be an expensive motor. Frankly the M820 does everything I had hoped for. I love this bike. The original promise of a short burst mode would have been nice tho.

Regarding DJI...don't need the power myself. I have my Bafang M600-120NM and M620-160Nm. But the wireless electronics are definitely setting the Gold standard and are super slick...this is an area that Bafang could strive toward?

Also, DJI reportedly does do a 5-10% battery reserve, so I'd like to see that become an "industry standard".

That and the walk mode of the M820 is virtually useless as it's intended. I'd like to see a bump up in Nms.

Superboost 85Nm 60-90 sec mode would be certainly be a welcome feature...original promised by Bafang in some form--DJI does this concept too of course...

Just a "simple" firmware update that someone has to urge Bafang to improve. So, keep refining the M820 Bafang!

 

[mike_kelly]

You can't forget that the chemistry of the batteries do not allow low discharge without damaging the battery. The batteries are expensive enough that I won't trade long life for low discharge.

 

[Freda]

This can not be explained with protecting the batteries. Bafang goes to battery saver mode at 20%, that means about 3,6V on each cell. Minimum voltage for each cell is 2,5V. It is of course not good in any way to go that low.

First of all they use a big margin, 20% instead of 5-10%. Second of all their percentage scale is all wrong, 20% is 40% on the JBD bms(maybe not correct either but good as reference).

It would be nice if someone with other manufacturer e-bike motor could measure battery voltage when percentage is 5-20%, to get some reference.

 

[TCFlowClyde]

This can not be explained with protecting the batteries. Bafang goes to battery saver mode at 20%, that means about 3,6V on each cell. Minimum voltage for each cell is 2,5V. It is of course not good in any way to go that low.

First of all they use a big margin, 20% instead of 5-10%. Second of all their percentage scale is all wrong, 20% is 40% on the JBD bms(maybe not correct either but good as reference).

It would be nice if someone with other manufacturer e-bike motor could measure battery voltage when percentage is 5-20%, to get some reference.

However Bafang or the battery maker can do it to the BMS, I'd take even 12.5% as a battery reserve mode for the M820.

 

[mike_kelly]

"There is a direct relation between the depth of discharge and the cycle life of the battery. The shallower the DoD, the exponentially higher the number of cycles given by a battery. By restricting the possible DoD in your application, you can dramatically improve the cycle life of your product.


As an example, Saft MP 176065 xtd’s full charge DoD is 4.2V, the lower charge is 2.7V. A 100% DoD at 25°C, using a C charge and a C/2 discharge rates will allow 4,000 cycles.
A 30% DoD allows 16,000 + cycles, ie 4 times more! A perfect example that fine-tuning DoD, temperatures and C rates can definitely extend your battery's lifetime.


To illustrate the idea, a 100% DoD could be compared to breathing hard, using your full lung capacity, thus exhausting your entire body. But if you are breathing normally, you can keep on moving longer. "

https://saft.com/energizing-iot/lithium-ion-batteries-use-5-more-tips-longer-lifespan

 

[mike_kelly]

Also not charging to full capacity increases the lifespan.
"For example, a lithium-ion cell charged to 4.20V/cell typically delivers 300–500 cycles. If charged to only 4.10V/cell, the life can be prolonged to 600–1,000 cycles; 4.0V/cell should deliver 1,200–2,000 and 3.90V/cell should provide 2,400–4,000 cycles."

BU-808: How to Prolong Lithium-based Batteries

BU meta description needed...

batteryuniversity.com

 

[TommyR]

I deal with this in my job, albeit for heavy duty electric semis, not bikes. So yeah, basically the same. LOL I suspect Bafang is just issuing a strong case of CYA. Personally, I would prefer they continue to allow full power below 20% as I feel it's a bit too conservative, but I understand why they do it. For the number of cycles I anticipate from my battery, I would personally be happy to enjoy full power below 20%. But to avoid the reduced power below 20% I opted for the larger battery. As a heavier rider, I figured it was the wise call. If I ever receive my bike, I hope to find out with some real world testing! LOL

 

[mike_kelly]

Among engineers minimum discharge voltage for lithium is a religious thing.

 

[TCFlowClyde]

Among engineers minimum discharge voltage for lithium is a religious thing.

I forgot that on my e-mtb fattie M620, I have two 600 Wh encased house batteries made by a DengFu Finnish electronics engineer, I believe the reserve setting is somewhere around 8%.

So, you're right, I'm just saying the tradeoff for slightly fewer charging cycles for that reserve setting is worth it to me. Damn the !

 

[mike_kelly]

I am too poor for such luxuries