Master V4 50S Linkage Suspension Ratio Movement Geometry Overview

[Julianjc84]

Begode v4 50s Master with Red Factory Linkages.
They are stamped with white MS label.

What I have measured and understood about the Master.
The Factory BEGODE v4 shock shock specs I measured are. Is there a spec sheet?
Open eye to eye ~ 198/200mm
Closed eye to eye ~ 164mm
Shock movement when oil filled ~33mm
Shock movement when oil drained out valve stem ~44mm

Note: The shock will move Eye to Eye Closed. 141.6mm+12 = ~154 mm 198-154 = ~44mm with the air valve stem core removed and placed in a clamp. However oil will ooze out the valve air hole. How much can you compress this shock? my safe limit was 33mm maybe can push it 36-42mm when it is oil filled.
If your shock pings, or oil is busting out the shaft later in life. i'd place my bets its likely because you had bottomed out the the shock and the hydraulic forces of the oil is blowing out the valve seals. i'm no engineer.

The Master is advertised with 80mm of stanchion travel. However -5mm is lost with the rubber o-ring at the pedal hanger and -5mm is lost at the top of the stanchion where it connects to the mainboard frame. Giving the Master stanchion a safe movement range of ~70-71mm.
The lower and upper linkage mounting points to the wheel frames are directly vertical and 100mm centers apart.

V4 Factory Red MS (master s linkage laser cut?)
Open linkages eye to eye ~ 187.56mm
Closed linkages eye to eye ~ 161.29mm
considerations:

• drain your shock day 1
• Pre compressed ~10.5mm bottom hole
• Pre compressed ~13.5mm top hole
• Top hole only really becomes useable if you drain the oil from the shock so you can get close as possible to full range of motion of the air shock.

V4 Factory Red Master S Linkage Lasercut-- 180 flipped upper linkage.
Open linkages eye to eye ~ 195.36mm
Closed linkages eye to eye ~ 166.51mm
Issues:

• Collides with light.
• Collides with seat frame.
• effort, and considering what i know now. use the top hole in factory configuration and drain the excess oil from the shock.

Pros:

• Excellent range of motion.
• Excellent movement curve.

My YouTube video link for Reference:

TLDR: it was fun buy 3rd Party Geometry is the way
My YouTube video of 3rd Party Linkage Generator far better solution.

FOOTNOTES:
photo references of linkages have been made with the use of photo reference and manually measuring with digital calipers.
+- accuracy 1mm ?

5mm Movement Graph of the Linkage Configurations

Ratios.
The Vertical Movement of the stanchion 71mm travel / by the Shock Eye to Eye movement.
TOP HOLE 2.34:1

BOTTOM HOME 2.94:1

FLIPPED 180 2.63:1

lower ratio = coil or shock has to be less lbs / work less hard.
high ratio = coil or shock requires high PSI and LBS to resist the forces.

Master v1.0 Factory Linkage Background Reference.
https://forum.electricunicycle.org/topic/30939-why-the-masters-suspension-is-terrible-and-how-to-fix-it/

Other great BEGODE shock references

https://youtu.be/JhICbhTWBXQ?si=a1jUOLyrJ2LZJjqz

Edited April 6 by Julianjc84
updated image ratios links

[Julianjc84]

Factory movement:

 

 

180 flipped top linkage movement

 

 

[EUC Custom Power-Pads]

In short, Master suspension still shit to this day. 

I changed the shock and linkage straight away after unboxing and wasted no time. 

[Panzer04]

There's something not quite right about your conclusions for the top hole on the linkage. The shock can clearly compress to the full range of motion for that configuration - my shock is set up that way (and I just tried deflating and inflating it and it worked just fine). Are your stats right for the size of the shock? I would assume it would lock out when it runs out of travel, not keep going. It looks like most 190mm shocks have 50mm of travel, so I would expect the begode shock to be more similar to that. I saw in your video you measured it - Are you sure you fully compressed the shock?

Thanks for those details, they are really interesting. I'm not sure how important the actual shock movement action is - I would think it doesn't really matter, so long as the shock is compressing some amount over the course of the travel movement. Assuming the shock movement action isn't important:

From what I can see, assuming the shock can safely compress on the hard hole (and I don't see why not, surely not even Begode could be that incompetent - and it seems fine on my V4) the hard hole definitely reflects its name. It starts a bit compressed, and will ramp up in the shock itself more progressively since it's already pre-compressing the shock quite a bit. It looks like it's both more progressive than the bottom hole linkage-wise, and more progressive in the shock because it starts more compressed and uses more of the shock volume.

EDIT: Also, because the hard shock uses more travel, it can use less pressure than the soft config too - about 25% less, presumably (1.5mm vs 2mm per unit travel)

The bottom hole only seems like something you'd use if you're strictly a street rider who wants most of the travel to be soft, because you will definitely blow through the whole travel much more easily - You'd also need 25% more PSI than the hard hole to start with (1.5 vs 2 ratio) - this actually lines up with my experience - I needed less pressure on the hard setting to get the right amount of sag with the hard hole, 200 rather than ~250 psi.

Your alternative configuration looks like a middle ground between the two, but I suspect it could actually be more linear than the bottom hole, as the shock is not precompressed - the air volume inside the shock will decrease by a smaller ratio as a result and the shock itself will be less progressive, counteracting the more progressive linkage action.

 

Thanks for the information, it's good to analyse these things properly - Lots of people shit on the stock configurations, but the hard hole setting, based on these numbers, actually looks reasonably solid, especially for people who had problems with the soft hole only. 32mm of shock travel for 71mm of shock movement is actually a reasonable ratio, compared to 21?mm on the earlier shocks.

 

Edited January 12 by Panzer04

[Julianjc84]

24 minutes ago, Panzer04 said:

Are you sure you fully compressed the shock?

I did try, However mistakes could have been made. I will have to remove it again and remove the valve stem core and crush it with a bigger clamp to hold its position while i take photos.
It would be nice if there was a spec sheet for the Begode Factory air stock.
It will change quite a few things if the factory air stock allows movement travel of 45-50mm like you say.

24 minutes ago, Panzer04 said:

I'm not sure how important the actual shock movement action is - I would think it doesn't really matter, so long as the shock is compressing some amount over the course of the travel movement. Assuming the shock movement action isn't important:

I belive a clean movement linkage curve is important. Near the end limits of the factory configurtation the movement reverses direction. This unsettles me.

Edited January 12 by Julianjc84

[0000013]

https://t.me/begode_master/115745
This is an Excel file to calculate the suspension movement.

[Julianjc84]

On 1/12/2024 at 9:13 PM, 0000013 said:

https://t.me/begode_master/115745
This is an Excel file to calculate the suspension movement.

This document is amazing and Russian! Thankyou.
I customized and edited a bit and made more accessible in a google doc.
https://docs.google.com/spreadsheets/d/1df77qPoMnHwik-T-hHIqtEl9jAk_xfDVS4XdZOqhT9c/edit?usp=sharing

NOTE: Something to consider the ratio graph does not reflect the actual motion and movement the linkages take.
When link B and link D are different lengths the motion of geometry movement curve is not very clean and depending on what link is longer and by how much the curved movement motion will push the link up or downward.

Edited January 18 by Julianjc84

[Panzer04]

I've just swapped my air shock out for a coil, and I believe it vastly improves the shock response, especially early in the travel. My current coil is too soft, but with that caveat it's otherwise significantly better. At least the DV22-AR shock I'm using allows enough loosening of the coil that it's no longer preloading the suspension. The air shock is designed for 195-200mm or whatever, so it's simply too long and will be heavily preloaded with the stock shock configuration. By unwinding the coil I can ensure the shock isn't preloaded, which makes it much more responsive to smaller bumps.

The lower stock stiction (and probably combined with the preload) is also very helpful, as the entire suspension actually moves in response to my movement - the air shock would actually barely move, even after loosening all the sliders, unless I was putting real work into bouncing it. I think as a way to reject small bumps etc, a coil shock will function way better than the air shock, and it also functions pretty well in the normal hard/soft hole configuration rather than having to flip the linkage to avoid preloading the air shock. It now actually feels bouncy, rather than like some sticky sliding motion that only really dampens big bumps or jumps.

Not having to overcome like 50kg of preload (as it is with the air shock) is IMO the biggest win though. No more clunky top-outs , and better compliance on bumps, especially if the wheel leaves the ground. It does require a stiffer spring from ali though, if I want to avoid bottoming out on anything bigger than a curb, hopefully those also fit (ie. aren't too long or wide)

Edited January 19 by Panzer04

[0000013]

In the stock shock absorber, too thick oil has been poured into the oil chamber. Even when the rebound is fully unscrewed, the suspension is released too slowly I replaced the oil in the oil chamber with a thinner one. Applied bicycle brake oil. Now it's good.