Sur-Ron - New Mid drive Bike

[sc-surfer]

Got it. I presume that just makes the shunt read low on current so the BMS doesn't freak out??? Will the BMS now not read capacity correctly? Seems the 'gauge' would read low? If that's the case, are you just using voltage to estimate battery SOC??

[Hawaiiguy]

That guys soldering was terrible.

[fechter]

Yes it will affect the battery gauge. If you run the pack all the way down to cutoff and fully recharge the gauge will try to recalibrate itself. You may need to do this more than once to get it accurate.

Soldering on the board is challenging because it's an aluminum board. You need an iron with a lot of heat and it's likely to end up looking like that picture.

[AZeBikeGuy]

....Soldering on the board is challenging because it's an aluminum board. You need an iron with a lot of heat and it's likely to end up looking like that picture.

Oh for the love of god get out some wick or something =]

[Paulflieg]

Hallo,

Does anyone know which connectors are on the original controller? And where do you buy them?

[ethana4]

So I'm having an issue with my Sur.

I installed a new headlight/switch assembly. For some reason when I turn the light on it makes my speedometer act crazy.

I've tried numerous wiring configurations and different switches. I also connect and try them before actually installing them under the ignition panel. They work without affecting the speedometer this way, but when I install the ignition panel, it makes the issue happen.

I can't put my finger on what is happening.

Could really use you help. Thanks !

[fechter]

Which wire did you insert the switch into? Both the headlight and speedometer run off the 12v dc-dc.

[ethana4]

I wired a switch to the the lights cable and then plugged into the existing headlight connector

[fechter]

I wired a switch to the the lights cable and then plugged into the existing headlight connector

That's pretty strange. I can't think of any reason that would happen. You could try putting it back the way it was and see if the problem goes away.

[smdub]

Bad connection (power or ground) that goes loose when you shove all the wires back in place?
EMI is another possibility. The LED likely has a switching power supply and maybe not a lot of input filtering. A capacitor and/or ferrite bead would help if that was the case. Is it CE/FCC listed?

[JuiceMeUp]

light-bee-wiring-diagram.pdf

(1.09 MiB) Downloaded 59 times

[thoroughbred]

Hallo,

Does anyone know which connectors are on the original controller? And where do you buy them?

I'm guessing you are in europe? in usa we have
https://www.ebay.com/itm/WATERPROOF-9-P ... 2749.l2649

[Paulflieg]

Hallo,

Does anyone know which connectors are on the original controller? And where do you buy them?

I'm guessing you are in europe? in usa we have
https://www.ebay.com/itm/WATERPROOF-9-P ... 2749.l2649

Ahh yes, thanks ... With this info, I found the parts on Aliexpress the "old" controller had to give up its plugs for the new one.

[Bullfrog]

Can anybody tell me the head tube angle of a stock Sur Ron?

I have searched for it but not been able to find the spec...if it is listed somewhere a reference sure would be appreciated as well.

Thanks

[n2mb]

Has anyone measured the power output of the USB-plug from th Sur Ron? It says 5V 2,4A on it.
If so it would be enough to power an additional 10W LED on the handlebar without mounting the associated 1S3P batterybox.

Why not just use the 12V power? I run a 30W LED headlamp from it with no problem.

[sc-surfer]

Who's running the eMotoBros controller and display?? Any feedback?

[Ohbse]

It's an ASI - so... unreliable, comparatively difficult to configure, dodgy support (thanks to resellers rather than the company themselves).

It's better than the stock controller IF you can get it configured correctly.

Nucular is a better option in every regard, with the notable exception of its long, long lead times. Very reliable, plug and play with the Surron harness, exceptional support and very easy to make changes yourself with the display.

[thoroughbred]

After running the 19 rear wheel with a geomax knobby for a year I wanted to try a 18 as the 19 has small knobs and puny sidewall.

I followed offroaders nice write up and bought some supplies. Apparently, all ebay 12g sapim spokes are not created equally.

20210103_191251.jpg (229.76 KiB) Viewed 362 times

the hook portion of these is too short to allow assembly. Plan B was to reuse the oem spokes with the new rim by switching from 2 cross to 3 cross pattern

20210103_191312.jpg (230.83 KiB) Viewed 362 times

[Finer]

Can anybody tell me the head tube angle of a stock Sur Ron?

I have searched for it but not been able to find the spec...if it is listed somewhere a reference sure would be appreciated as well.

Thanks

63.5 degrees. I checked it because I ordered a 21 inch wheel and want to see what the difference is after the change.

[Bullfrog]

Thank You .

[smdub]

Can anybody tell me the head tube angle of a stock Sur Ron?

Per sur-ron.ro/.it/etc its 26deg (= 64deg in common head angle terms)
https://sur-ron.ro/project/light-bee-x/
https://www.aebikes.com.au/specifications.html
But there have been a couple different forks on the front (26 & 27.5) so who knows which that was measured with.

W/ the 1260mm spec wheelbase, every 1mm increase in axle height = asin(1mm/1260mm)=0.045deg.
From the stock tire, the difference was about 35mm radius = ~1.6deg => 64-1.6=62.4 (that is if I *ONLY* put a bigger front tire on)

Going to a Fox40 27.5 fork was ~15mm longer axle crown measurement than my orig 26" RST. That's roughly equivalent to 15mm*sin(64)=13.5mm lift = another 0.6deg => 62.4-0.6=61.8

Since I ALSO used a larger rear tire, the front radius only raised ~7mm => 0.3deg. So my total change is only 64-0.3-0.6=63.1. FWIW, both my KTMs (150 & 500) are 63.5deg. I've never measured the ACTUAL angle but the bike steers ok but not super quick. I've used it on the scouting lap for a trials competition and its definitely 'lazy' compared to those. I really haven't ridden it and the 150 hard back to back to know if I can even tell the difference between the two. I've thought about ordering the rear shock link that lifts the rear a little and see if I like it. I'm tall and can use all the height I can get. But I'm close to making the bike too tall for my wife to ride comfortably so I have to tread carefully if I want her to ride along w/ us.

(Someone please check my math to make sure I didn't screw up.)

[Bullfrog]

Can anybody tell me the head tube angle of a stock Sur Ron?

Per sur-ron.ro/.it/etc its 26deg (= 64deg in common head angle terms)
https://sur-ron.ro/project/light-bee-x/
https://www.aebikes.com.au/specifications.html
But there have been a couple different forks on the front (26 & 27.5) so who knows which that was measured with.

W/ the 1260mm spec wheelbase, every 1mm increase in axle height = asin(1mm/1260mm)=0.045deg.
From the stock tire, the difference was about 35mm radius = ~1.6deg => 64-1.6=62.4 (that is if I *ONLY* put a bigger front tire on)

Going to a Fox40 27.5 fork was ~15mm longer axle crown measurement than my orig 26" RST. That's roughly equivalent to 15mm*sin(64)=13.5mm lift = another 0.6deg => 62.4-0.6=61.8

Since I ALSO used a larger rear tire, the front radius only raised ~7mm => 0.3deg. So my total change is only 64-0.3-0.6=63.1. FWIW, both my KTMs (150 & 500) are 63.5deg. I've never measured the ACTUAL angle but the bike steers ok but not super quick. I've used it on the scouting lap for a trials competition and its definitely 'lazy' compared to those. I really haven't ridden it and the 150 hard back to back to know if I can even tell the difference between the two. I've thought about ordering the rear shock link that lifts the rear a little and see if I like it. I'm tall and can use all the height I can get. But I'm close to making the bike too tall for my wife to ride comfortably so I have to tread carefully if I want her to ride along w/ us.

(Someone please check my math to make sure I didn't screw up.)

Thanks smdub...you make some very valid points and your insight is very valuable and your calculations are awesome and exactly what I would be doing . I actually think it is acos but for the small changes we are talking about the change is virtually going to be the same whether you use asin or acos . I don't know about others but you can understand why I probably won't get a Sur Ron after getting the head tube angle info since I ride in tight single track trails most of the time with my top speed being approximately 17-18 mph.

The head tube angle on my BBSHD Ludicrous powered hardtail is 70 degrees and I like the steering on it. I have a fat tire bike with the same drivetrain that has a 68 degree head tube angle and I run a 27.5x2.8 front tire with the 26x4 rear tire and the steering on it is on the verge of being too slow for my personal preference.

If my speeds were faster then the lower angles would be nice and provide more stability but for the woods where I ride, I like something that steers relatively quickly. Sort of sucks because I'd like to build a full suspension ebike but head tube angle for all the current crop of full suspension bikes is pretty low. The lower angles are great for riding off the side of a mountain or high speeds but they suck when you are going 18 mph in the tight trails and need to make turns .

[smdub]

asin() is correct as acos(~0)=90deg. Big difference. SOHCAHTOA

Trail is as big a factor as head angle so don't discount that. Early 29ers w/ 26er low axle offset steered like crap until new high offset forks came about and reduced trail back to a reasonable number. Not sure which downhill forks have higher offsets but you could definitely get/make offset triples.

This is as close to as I have found for head angle on the trials bikes. 73deg. I have Shercos instead of GasGas but I suspect they are all similar. They have razor sharp handling.


I would like to try the Sur-Ron in a trials competition. There are a couple Electric Motions & OSETs that ride in local events. What its really lacking is steer angle though. You just can't turn the forks close to 90 deg left/right like you can on a trials bike. My old Betas would actually go past 90deg.

I see you are trying to adapt the Sur-Ron to something what it wasn't really designed to do. Nothing wrong w/ that(!) but is a 110# bike really going to be all that much fun in TIGHT single track even w/ better geometry? W/ a 1.6 gearing change like you asked for in the other thread, and the resultant increase in torque, it might end up as an overpowered, overweight, trail-destroying machine. (I recently installed a Nuc24F looking for more power and its a blast but its wreaks havoc on the yard and I'd never take it on the mtb trails.)

[Hawaiiguy]

I ride tight single track all the time and I think the steering is plenty quick enough,I am also running the Bac8000 set to 13500w and it’s a blast to ride and climb steep hills.My friend rides his trials bike with us and he has no advantage.

[3DTOPO]

Sup y'all!

So after over 2,300 tubeless miles it was time to replace my trusty Bridgeport M403 with the newer M203.

The first tubeless conversions I had to use a strap around the tire to get enough of a seal for the tire to inflate. It really was the most pain-in-the-ass task in the whole procedure.

Welp, this time I removed the the spoke protector rubber and used a narrow strip of gorilla tap in the U-channel. I then added another slightly narrower band in the U-Channel over that to kind of fill it in. Then one more band on top of that the full width of the rim.

This gave me a good enough seal to eliminate the need for using the strap! Filled right up with just an air compressor. It's such an easy process now I could not recommend going tubeless enough.