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

[TCFlowClyde]

Shouldn’t this be in the DIY ebike builds section instead of the motor section?

Sure, it could be, as soon as other M820 frames come online. But it's probably more relevant to the new M820 specifically, and then toward the CEF50 frame of course. It's under "Bafang" main category, which tends to be predominantly a DIY-build inherently. Plus, the subcategory is fairly explicitly entitled: "M820--CEF50 frame".

Also, it's the only M820 frame currently being offered to the direct consumer as yet, the two other prospects TanTan and LightCarbon are likely to look at proprietary build distributors aka regional dealership/bike shops...so access may only be the CEF50 frame paired with the M820 in the immediate future.

Sidenote: I'm hoping DengFu jumps in with a M820 enduro offering to the direct consumer first, or even exclusively, too. I have a e-fat bike full suspension from them and they make nice DIY frames like the E10.

Anyway, it's most relevant and logical here for now,. Unless the powers-that-be want it somewhere else.

 

[TCFlowClyde]

use that for dual battery???

IDK. I was hoping you would figure it out first.

It's the main reason I went for the larger 720Wh battery. I assumed that a DIY extender would be made by others more competent at battery building.

 

[thaeber]

use that for dual battery???

Just checked Aliexpress, and yes, that’s what You need. I‘m just not sure about the balancing function of this box, if this is able to balance 2 batteries with same voltage but different SoC. This would be good, to avoid any damage if You forget to charge both batteries before connecting. If this is not the case, You can use a simple Y-cable connector:

 

[Moderator]

Sure, it could be, as soon as other M820 frames come online. But it's probably more relevant to the new M820 specifically, and then toward the CEF50 frame of course. It's under "Bafang" main category, which tends to be predominantly a DIY-build inherently. Plus, the subcategory is fairly explicitly entitled: "M820--CEF50 frame".

As @TCFlowClyde says, whilst normally a build/frame thread would be in the DIY section, as this is the only M820 frame, it seems directly relevant to the M820 motor thread so for the moment it's probably quite a good place for it.

At some point, we will move it to the DIY section.

 

[TCFlowClyde]

Just FYI and point for clarification: the CEF50 frame should being using the DP-E181.CAN display/remote power selector only for the M820 motor kit as expected. Confusion was that the preliminary setup (pictured below) had at least two other systems tossed on it incorrectly...it's a new motor system and new frame-line afterall, so they're just getting it dialed in.

In a nutshell:

The frame should (still waiting 4 official confirmation but sales dept knows) have the minimalist handlebar mount display/mode selector combo with Bluetooth to likely use w/your smart phone? (still could be smaller). It's the 5-bar, green-LED battery indicator/5-bar blue-LED power mode selector (below).

No top tube frame integrated display,

 and

No remote handlebar switch and colored display near the stem (my preference honestly, would luv to see this cross compatible with M820, but doubt it would happen ).

 

[stuff]

Hey,
I ordered also the same frame, once it arrives by end of february i’ll post some pics. From Linda also.

My build will be as light as possible, hence I ordered the 410w bafang battery.
Components:
Rs pike ultimate @ 160mm (although the geo it says 170, it’s wrong, that frame is intended for 150/160 (by checking headset to fork axle length
Rs deluxe ultimate 210x50
Slx m7120 brakes
Xt drivetrain w 10/45 cassette
Renthal carbon handlebar
Carbon wheelset w EIE rims, sapim d-light and ztto m1 hubs 29” / 30mm internal
Carbon isis cranks
Sdg tellis dropper
Prolly assegai/aggressor combo

Already got most of the components, its a matter of waiting for the frame/motor/battery now

Aiming to 17-18k, i’m 69k so those components should be more than enough for me.

 

[temon10]

Hey,
I ordered also the same frame, once it arrives by end of february i’ll post some pics. From Linda also.

My build will be as light as possible, hence I ordered the 410w bafang battery.
Components:
Rs pike ultimate @ 160mm (although the geo it says 170, it’s wrong, that frame is intended for 150/160 (by checking headset to fork axle length
Rs deluxe ultimate 210x50
Slx m7120 brakes
Xt drivetrain w 10/45 cassette
Renthal carbon handlebar
Carbon wheelset w EIE rims, sapim d-light and ztto m1 hubs 29” / 30mm internal
Carbon isis cranks
Sdg tellis dropper
Prolly assegai/aggressor combo

Already got most of the components, its a matter of waiting for the frame/motor/battery now

Aiming to 17-18k, i’m 69k so those components should be more than enough for me.

Linda already send it?

 

[LAnton]

Hey,
I ordered also the same frame, once it arrives by end of february i’ll post some pics. From Linda also.

My build will be as light as possible, hence I ordered the 410w bafang battery.
Components:
Rs pike ultimate @ 160mm (although the geo it says 170, it’s wrong, that frame is intended for 150/160 (by checking headset to fork axle length
Rs deluxe ultimate 210x50
Slx m7120 brakes
Xt drivetrain w 10/45 cassette
Renthal carbon handlebar
Carbon wheelset w EIE rims, sapim d-light and ztto m1 hubs 29” / 30mm internal
Carbon isis cranks
Sdg tellis dropper
Prolly assegai/aggressor combo

Already got most of the components, its a matter of waiting for the frame/motor/battery now

Aiming to 17-18k, i’m 69k so those components should be more than enough for me.

What is a Pike 160mm under 29 wheels? Under 29 wheels 150 maximum in the old version was.

 

[LAnton]

If everything goes well, we will receive the frames in mid-March

 

[TCFlowClyde]

If everything goes well, we will receive the frames in mid-March

 

[stuff]

Linda already send it?

Nope, told me since chinese new year and covid she will be sending it by end of february.

 

[stuff]

What is a Pike 160mm under 29 wheels? Under 29 wheels 150 maximum in the old version was.

Pike can go to 160 on 29. It’s a 2021 fork

00.4020.552.000 that’s the part # for the debonair that I needed, and works perfectly

 

[stuff]

Those 572mm equals a 160 fork. Although anything 10mm+- would do fine also just modifying seattube, HT angle and bb height

 

[temon10]

View attachment 104316

Those 572mm equals a 160 fork. Although anything 10mm+- would do fine also just modifying seattube, HT angle and bb height

You right mate, dont overspec for safety. For me 160 travel is enough for Enduro riding.

 

[TCFlowClyde]

You right mate, dont overspec for safety. For me 160 travel is enough for Enduro riding.

You should be able to fit a 170mm 29er fork with little worries. Sure, 180mm might be pushing it.

Here's my 180 27.5er + measurements top-crown to mid-axle = 560ish.

Also, I ran the specs and plan to overstroke the frame by the Lost Co. bike shop....spoke to owner/YouTuber channel, long hair dude. If it helps, he does a ton of big suspension rebuilds and rides big PNW bike parks apparently.

 

[TCFlowClyde]

Nope, told me since chinese new year and covid she will be sending it by end of february.

Well, I think that would be optimistic...but I hope so.

This is my 6th DIY China-direct frame (4th E-mtb) since 2016. If they have current stock during non-COVID pandemic times, 4-6 weeks to the US is good. Recently, COVID has made a major rebound in China mainland due to lockdown release... unfortunately this may slow everything again. But a year ago, with low infections levels, DengFu was on it, right before X-mas shipping slog and got it to me from stock in 2 weeks.

Chinese lunar New Year often gets celebrated in effect 2-3 weeks starting soon! Expect lots of delays. This is a new production line for them. The M820 is new. "New" usually means inherent set backs...I hope not, but realistically, likely. Plus, they haven't made the frame molds yet, as I understand it (someone may want to confirm).

 

[thaeber]

You should be able to fit a 170mm 29er fork with little worries. Sure, 180mm might be pushing it.

Here's my 180 27.5er + measurements top-crown to mid-axle = 560ish. View attachment 104345

Also, I ran the specs and plan to overstroke the frame by the Lost Co. bike shop....spoke to owner/YouTuber channel, long hair dude. If it helps, he does a ton of big suspension rebuilds and rides big PNW bike parks apparently.

View attachment 104343 View attachment 104344

The 27.5 makes the difference, You can easily run the 180 fork with the 27.5 wheel and stay closed to 560 mm fork length. The 160 travel @ 560 mm in frame spec are referring to a 29 wheel.
With my E10 that has basically the same recommended suspension specs I installed a 180 mm fork /29 wheel and a 216 mm shock instead of 210 and 27.5 rear wheel. Ending up 170 mm rear travel, 63.5 headangle, 358 BB hight - bottomless and plush, rides like a dream. I would do exactly the same with this CEF50 frame…

 

[TCFlowClyde]

The 27.5 makes the difference, You can easily run the 180 fork with the 27.5 wheel and stay closed to 560 mm fork length. The 160 travel @ 560 mm in frame spec are referring to a 29 wheel.
With my E10 that has basically the same recommended suspension specs I installed a 180 mm fork /29 wheel and a 216 mm shock instead of 210 and 27.5 rear wheel. Ending up 170 mm rear travel, 63.5 headangle, 358 BB hight - bottomless and plush, rides like a dream. I would do exactly the same with this CEF50 frame…

Luv'n those Enduro travel upgrades!

I was too afraid to try a 216 e2e fitment. I think the leverage ratio is 2:1 so likely 10 mm bump in the 210x55. I'll take 160 mm safely.

It would be nice to see the progression curves to better predict the kinematics, but honestly I didn't want to pelt Linda salesperson with more tech questions and overburden her. Maybe someone else might inquire out of curiosity?

But hurry! The factory shuts down the 12th, tomorrow...I'm still waiting to find out if the engineer making the frame molds knows that the top tube doesn't need an unnecessary hole in it, unless it's just a basic on/off power switch instead of the DP-171 display as shown in my pics.

 

[Vsoria]

 

[LAnton]

Jean gave me these photos

 

[temon10]

Jean gave me these photos

View attachment 104390 View attachment 104391 View attachment 104392 View attachment 104393 View attachment 104394

it's different rearshock, only 200. Linda give me spec 210.

 

[stuff]

it's different rearshock, only 200. Linda give me spec 210.

Nope, it’s 210 (check it over the graph)
Those 200 are to the thread thats between the frame and the linkage

 

[TCFlowClyde]

I had to review a few articles/vids to remember how to calculate a rear shocks leverage ratio (it's straightforward) to see the hanging curve vs. hump progression curves in general. It looks like the leverage ratio is 3:1 (150mm travel/50 mm stroke length = 3). So, for every 5 mm of overstroking the rear shock, I should get 15 mm of new travel for a total of 165 mm.

Since I kept it in the 210 mm eye-to-eye length, it's still the 3:1 leverage rato. It should produce the same leverage curve. Thus the behavior characteristics should be predictably similar too.

For the CEF50, the leverage curve is a progressive "hanging curve", and the kinematics of travel will behave more or less according to Bike Radar as the following. "...That means they have a high leverage ratio at the start of the travel to soften the initial stroke and quickly drop to a lower ratio in the middle of the stroke to add support after sag. This is particularly relevant when using an air shock as they tend to be firmer in the beginning stroke and softer in the mid-stroke, relative to a coil."

So my interpretation: the frame travel should yield plushness from begining of the travel,, but not wallow in middle, and then ramp up at the end of full travel to prevent/minimize bottoming out.

 

[thaeber]

This looks VERY progressive to me. Starting at a leverage ratio of 3.6 at beginning of stroke and ending with a leverage ratio of 2.5 at end of stroke. Compared to the E10: 3.1 to 2.6 according to chart attached.
My takeaway:
- Coil shock would be a better choice due to linear spring rate
- Overstroking 216/63 would raise the rear by (6mm longer shock x 2,5 ratio) 15 mm and increase travel by (13 mm increased stroke x 2,5 ratio) 32,5 mm! to 180+ mm rear travel!
- Overstroking 210/55 would increase rear travel (5 mm increased stroke x 2,5 ratio) by 12,5 mm to appr. 162,5 mm

Sound promising!

 

[TCFlowClyde]

This looks VERY progressive to me. Starting at a leverage ratio of 3.6 at beginning of stroke and ending with a leverage ratio of 2.5 at end of stroke. Compared to the E10: 3.1 to 2.6 according to chart attached.
My takeaway:
- Coil shock would be a better choice due to linear spring rate
- Overstroking 216/63 would raise the rear by (6mm longer shock x 2,5 ratio) 15 mm and increase travel by (13 mm increased stroke x 2,5 ratio) 32,5 mm! to 180+ mm rear travel!
- Overstroking 210/55 would increase rear travel (5 mm increased stroke x 2,5 ratio) by 12,5 mm to appr. 162,5 mm

Sound promising!

View attachment 104418

I'll take 162.5 mm travel boost too!

 

[TCFlowClyde]

Issue or not?

Here's how Linda replied to my inquiry about the two independent display/power mode systems (frame-integrated DP-171 v. bar-mounted DP-181) being mutually compatible or not (see below).

Apparently, the molds can't be changed unless they have 20 units sold requesting that customization. I assume of each frame size.

Two choices if you order now or have ordered (like me and a few others here):

1) Simplify but patch: Use the DP-181 handlebar mount display only, but you'll have to plug the frame display cutout however you see fit. (I have a DIY carbon kit I use for my carbon rim repairs and could access the hole and patch it fairly easily via the head tube.)

2) Trust both work together: Leave it as is and hope the both systems are compatible as their engineers say.

l'm inclined (but reluctant) to patch it and simplify the display/power function to one system, the DP-181 handlebar display, unless the two systems work really well together. Plus, I can shed some weight, however much, by dumping the electronics of the integrated display (the DP-171).

Consequently, I'll keep my order and risk that their engineers are correct. If not then plug the cutout as the last resort. So, it may be a non-issue for your needs.

Hope this helps?

 

[thaeber]

This would not bother me. In case I dont need the hole, I would DIY a holder for my phone using that as a mounting point. Perfect place to put the phone on this area of the top tube, I did this on my E10. Way more secure as on the handlebar, and very good visability!

 

[TCFlowClyde]

This would not bother me. In case I dont need the hole, I would DIY a holder for my phone using that as a mounting point. Perfect place to put the phone on this area of the top tube, I did this on my E10. Way more secure as on the handlebar, and very good visability!

View attachment 104443

Great idea!!!

I'll likely be mounting my Smartphone on my bars for speed/mileage/maps anyway...safer on frame!

 

[TCFlowClyde]

This would not bother me. In case I dont need the hole, I would DIY a holder for my phone using that as a mounting point. Perfect place to put the phone on this area of the top tube, I did this on my E10. Way more secure as on the handlebar, and very good visability!

View attachment 104443

BTW: Very nice E10!

180mm F/180mm R?

 

[Zimmerframe]

Two choices if you order now or have ordered (like me and a few others here):

I don't think it's an issue. It gives you options down the line if other things do become available.

Alternatively, you could install one of those little liftout ash trays like a car from the 70's.