Sur Ron vs. DIY hub motor bike?? Which would you recommend?

General Discussion about electric bicycles.
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mbgjt1   10 mW

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Sur Ron vs. DIY hub motor bike?? Which would you recommend?

Post by mbgjt1 » Sep 27 2020 10:57pm

HI all,

Instead of an ebike build with the QS205 motor, I was thinking of buying the Sur Ron and then also buying the BAC 8000 controller with the LiteSpeed 72V battery.

The bike is 3600 USD stock.. does anyone know how much the controller and battery cost?

Would it be at all possible to buy the bike without the stock controller and battery, since these will be replaced anyway and not needed?

What is your advice? I would like something for trail riding, not planning to do any jumps :)

John in CR   100 GW

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Re: Sur Ron vs. DIY hub motor bike?? Which would you recommend?

Post by John in CR » Sep 28 2020 1:11am

Have you ridden one? They seem too small for anyone above average size. Plus I'm too spoiled by silent hubmotors to put up with the sound of a high rpm motor unless high rpm is only at high no small drive sprockets or pulleys for me. You'll learn more, can build something better (though likely heavier), and get more self satisfaction building one yourself. For trail riding, unless they're generally flat light trails, a hubmotor isn't the way to go, though there are guys like MadRhino who get the most out of hubbies offroad.

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serious_sam   1 kW

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Re: Sur Ron vs. DIY hub motor bike?? Which would you recommend?

Post by serious_sam » Sep 28 2020 5:14am

mbgjt1 wrote:
Sep 27 2020 10:57pm
I would like something for trail riding,
I haven't ridden a surron, but I think I'd like one. It's an actual "dirtbike". Dirtbike pegs. Dirtbike seat. Dirtbike balance.

I own a pretty fast downhill bicycle frame modified with a MXUS 3K and Nucular 12F. 11kW peak. 100km/h. It is a lot of fun.

BUT, its still a bicycle, with a bicycle seat, and a big fat hub motor in the back wheel. Fast as fck in a straight line, but in my opinion, hub motor bikes handle like shit. It's just physics. The rear wheel is nearly 1/2 the weight of the bike. There's no way to fix such a massive unsprung weight in the back wheel. No amount of suspension tuning will make it better than a traditional chain drive. No matter what madrhino says, his bike might be the best handling hub bike on the planet, but still not better than most traditional drivetrain bikes. It's just not physically possible. The ratio of wheel mass is very close to the sprung mass, so their natural frequencies are very close, which means that the transmissibility of force is very high = bad handling. Put simply, when the wheel hits a bump and goes up, it forces the bike up, and there's not enough bike mass to react and push the wheel back down. You make the spring harder to push the wheel down harder, but it also has the effect of pushing the bike up harder. You just can't "tune" it out.

Hub motors have a lot of good traits though. Simple. As mentioned, usually pretty quiet. Low maintenance. Decent power available. Relatively cheap. Easy to convert. Maintain the bicycle look for legal reasons, or for the use of high quality bicycle components. Satisfaction of DIY conversion. For these reasons, many people go that route, including myself.

But back to the surron. It doesn't suffer from that massive rear wheel mass, and also has a traditional motorbike seat, so you can slide/move your weight forwards and backwards easy like on a traditional dirt bike. So balance is much better.

So based on my history of riding dirt bikes, and the fact that a surron is more like a traditional dirt bike, if you don't have any legal issues riding the surron, then that's what I'd suggest.

And wrt controllers, if you go on the Nucular "Telegram" app chat, you'll see a lot of happy customers running their 24F on surrons (with upgraded battery packs).

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MadRhino   100 GW

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Re: Sur Ron vs. DIY hub motor bike?? Which would you recommend?

Post by MadRhino » Sep 28 2020 9:59pm

They are too different to compare. Building yourself has the potential to make exactly what you want. But, if you want a mid drive ‘pit bike’ motorcycle, why would you build a fast hub motor ebike, or vice versa.

You first need to define the type of bike that suits your requirements, then compare various solutions of this type.
Make it fool-proof, and I will make a better fool.
Current bikes
Trek Session 10 mod. Variable geometry. 70mph
Santa Cruz V10. 50mph

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