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Comment by cjensen | Hacker News Reader

"it can quickly be located and tracked via GPS" but the only radio in it is Bluetooth, so I guess you can track it if you're in the same room...

"36V Lithium" battery, but no spec about how many kWh it stores.

"Top Speed 20mph". Given that it only operates when the human puts in some effort, what does that even mean? I'm guessing this is written down because US Law says if it goes faster than 20, it's no longer a bike.

"In 2011 Niko Klansek introduced the first line of electric bicycles to the USA market." Nope; ebikes have been available in the US for far longer than that.

GAH. There are lots of conversion kits you can buy today. The kickstarter gives no way for you to figure out if this is anything better.

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'"36V Lithium" battery, but no spec about how many kWh it stores.'

Speculating here…

They look like standard 18650 cells to me - they're readily available in both LiFePO4 and LiPo chemistries, but with 22 cells visible in the pictures, I'm guessing they're LiFePO4 because the nearest configuration to "36V" I can think of for 22 cells is 11S2P LiFePO4 cells at 35.2V, (the LiPo cells in 11S2P would be 40.7V nominal - a 10S LiPo would be "37V", but that doesn't make sense with 22 cells all up - maybe a 10S2P "motive" battery and an independant 2S pack to run the electronics?).

Typical LiFePO4 cells in 18650 size are 1350mAhr, so I'm guessing thats a 2.7Ahr @ 35.2V or a 95Wh - call it a 0.1kWh if you like. That seems a little low to get the indicated range/speeds quoted though - if you assume reasonable efficiency at half power, and that the bulk of power at top speed is aero drag, then the 250W used to ride at 25kmh would drop to doing only 19.5kmh at 125W (power going up with the cube of the speed thanks to the v squared term on the aero drag), so your 90Whr battery will only get you ~15km. If you halve the power again to 65W, and drop to 15kmh, you'd still only get a range of ~21km.

If they're LiPo cells though (with their increased fire risks), you can get inexpensively 2600mAhr cells in 18650 size - 22 of them (ignoring the difficulty in configuring a "36V" pack) gives you a bit over 210Whr - that'd still only give a 32km range @19kmh based on my assumptions above. Cells of 3000mAhr and over are around, they'd give you 244WHr and get maybe 40km @ 19kmh and _perhaps_ 50km @ 15kmh (but that'd take you 3 hours 20 mins)…

The "1000 cycle" battery life perhaps suggests LiPo instead of LiFePO4 (which is more commonly quites as "2000 cycles").

If I had to guess - I'd say it's a ~100Whr LiFePo4 pack at 35.2V, ad that the "50km" range relies on you providing over% of the motive power and travelling at a maximum of half top speed or so.

250w should get you close to 35kph on flat terrain. The limit is 25kph due to the legal laws not physical ones. The upside is it should be able to do 25kph up a steep hill just fine and there range numbers are reasonable. Edit: Ok, not all that steep a hill.

Hmmm - I've no good evaluation of this page's accuracy, but the first graph here says a 90kg bike/rider needs 250W to maintain 20kmh up only a 4% gradient hill. That's not very "steep". 20kmh up a 10% grade (which _is_ a "steep" hill) requires ~600W.

http://theclimbingcyclist.com/gradients-and-cycling-how-much...

A GPS module is of course also located on the Smart Wheel itself so it sends a signal on its own once the motion sensors (that turn on only after you lock it) notice it's moving without your knowledge.

The top speed means exactly that - because the Smart Wheel is a pedal assist this means it helps you accelerate until you reach 20 mph and no further. You're correct in stating that the top speed is also set in accordance to the US Law (or European Law, which allows for speeds up to 25 km/h).

We're sorry about the confusion about "the first line of electric bicycles" - this was of course meant to inform the reader about the first line of e-bikes that we're introduced by FlyKly, not the first e-bikes EVER.

Parent is asking how the wheel can notify the phone that the bike is moving if the phone is currently out of bluetooth range to the wheel

"A GPS module is of course also located on the Smart Wheel itself so it sends a signal on its own once the motion sensors (that turn on only after you lock it) notice it's moving without your knowledge."

Sends a signal to what? If you're a few feet away I don't think you'd be worried about a theft.

So if you're within a few feet of your bike when someone takes it, it will notify you? And it will track the bike for a few seconds as it goes out of range?

Your KickStarter calls this "located and tracked" without caveats. That's pretty misleading.

That doesn't make sense. GPS is not a transmitter. Will you include an embedded 3G SIM card (like a Kindle)? I'm not sure how you will get the GPS coordinates to the smartphone 10 miles away.

...the motion sensors (that turn on only after you lock it) notice it's moving without your knowledge.

Is there any reason that "locking" doesn't render the device immobile? I realize someone could still carry it off, but most thieves would be more reluctant to steal a device they have to take apart and hack before using, than one they can literally just ride away.

I assumed they meant the bike is being geographically displaced and that yes the wheel mechanism would be locked. For example if you pick up the back wheel and push the cycle on the front one only.

Top speed of 20mph specifically means that the electric assist cuts out at 20mph, and you're correct in assessing the reason. If you want to go over 20mph, you either need to do it with pedal power or get registered as a motorcycle.

Not true. The Specialized Turbo goes up to 45 km/h with some assist.

" e-bikes must have a motor of less than 750 watts and an unassisted speed of less than 20 mph. Because the Turbo is an electric pedal-assist bike, meaning you have to pedal to get any kick from the motor, the speed limit doesn’t apply. In fact, the only reason it tops out at 28 mph is to comply with European laws, which restrict e-bikes to 45 kph. Specialized installed a governor on the Turbo that automatically turns the motor off when it reaches this speed."

http://www.outsideonline.com/outdoor-gear/bikes-and-biking/B...

I think that, in Europe, that would be called a bike, not a bicycle.

http://en.wikipedia.org/wiki/Electric_bicycle_laws#Europe:

"European Union directive 2002/24/EC exempts vehicles with the following definition from type approval: 'Cycles with pedal assistance which are equipped with an auxiliary electric motor having a maximum continuous rated power of 0.25 kW, of which the output is progressively reduced and finally cut off as the vehicle reaches a speed of 25 km/h or if the cyclist stops pedaling.'"

Being a bike means (depending on the country) that you have to use a helmet, insurance, drivers license, cannot ride on an optional cycle lane, etc.

...the only radio in it is Bluetooth...

I guess I just assumed from the comment in the video about SMS that it would integrate a Qualcomm chip or something. But now that you mention it, that seems a stretch. Such a component would serve no other purpose, and really change the pricing.

...the first line of electric bicycles...

Really suspect that "the" should be "our". I have sympathy for non-native speakers of English, but this is an error that ought to be fixed, since it really undermines their credibility.

...really change the pricing.

By about $60: https://www.sparkfun.com/products/9533

More like by about $240. Most hardware has at least a 4x markup from BOM to MSRP. They're not selling it for BOM cost plus a flat 'profit'.

Of course sparkfun also isn't selling at cost. That module probably costs them $30 in volume. So maybe it would only be $120 in added cost.

They show about 20 cells. For cheap lithium ion batteries, that will be something like 150 to 200 watt hours. This is not a ridiculous figure relative to the stated range.

I counted 22. I'm suspecting thats either a 35.2V 11S2P LiFePO4 pack with probably under 100Whr, or a 40.7V LiPo pack which could be upwards of 250WHr (and could get ~200Whr quite inexpensively). Another possibility it that it's a 37V 10S2P motive power battery and a 7.2V 2S pack to power the non-motive electronics (microcontroller/gps/bluetooth/…)

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