Weight Weenie Ebike

General Discussion about electric bicycles.

Re: Weight Weenie Ebike

Postby LewTwo » Sat Jul 04, 2015 3:56 pm

mfj197 wrote:As tln says, this thread has all the weights for the BBS01.
Many thanks to tin and you as well for the reference thread.

I have been running the numbers and make the Bafang bottom end to be about 4.5 KG. If I consider the lightweight front hub motors run about 2 KG with another 0.5 KG for the controller then I come up with a delta of 2 KG that will be partially offset by the BB and crank set. That can be anywhere from 0.65 to 1.6 KG with 1 to 1.25 KG probably realistic for something not too exotic (read as expensive). That is making it close enough to bear consideration.

Also I note from the EMVev web site that the BBS01 is lighter than the BBS02:
"The BBS01 is very similar to the BBS02 except it uses a slightly smaller motor internally and is therefore ~0.5kg lighter"
Attachments
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Weight Comparison
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Re: Weight Weenie Ebike

Postby mfj197 » Sun Jul 05, 2015 5:30 am

LewTwo wrote:Also I note from the EMVev web site that the BBS01 is lighter than the BBS02:
"The BBS01 is very similar to the BBS02 except it uses a slightly smaller motor internally and is therefore ~0.5kg lighter"

The weights already given are for the BBS01. Yes, the BBS02 is half a kilo heavier and also it needs 13S batteries (if you get the 750W version) which adds more weight.
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Re: Weight Weenie Ebike

Postby LewTwo » Mon Jul 06, 2015 2:30 am

Reality is beginning to set it :roll:

I spent most of the weekend building a spread sheet for all the parts required to build the bike out based on a pedal only 2x8 derailleur configuration. Most of the time was spent digging up weight values for the various components. I am probably high on some and low on others. Also some of the components I listed might not be the optimum choices. It did however give me a starting point to do some comparisons. Unfortunately that starting point is right at 22 pounds :cry:

The good news is that is 6-12 pounds lighter than my precious starting points. I made copies of the spread sheet and modified them to remove and add components to get the theoretical weight of various configurations. It was an enlightening endeavor. Among other things I discovered that using a 3 speed IGH rear end came out lighter than the 2x8 derailleur configuration. I also came up with only a 1.33 pound difference between the Q100 front hub and the Bafang mid drive. Some of that is due to the fact that the pedal only configuration used a cheap mid range crank and bottom bracket. Regardless I am looking at about 31 pounds for either one of the ebike versions --- still much better than my current 60 plus pound grocery getter. 8)

The front hub would offer the advantages of lower cost and be easy to convert back to the 22 pound pedal only mode. The Bafang offers better potentially drive efficiency, simpler build and aesthetic appeal. I am leaning toward the Bafang mid drive despite the extra weight but I am going to take a closer look at the cost numbers first.

I have attached the spread sheet file to this post for anyone that might be interested.
Weight Comparison(old).png
Weight Comparison(old).png (68.3 KiB) Viewed 1052 times

See revised spreadsheet below:
http://endless-sphere.com/forums/viewtopic.php?f=3&t=70586&p=1069320#p1069320
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Re: Weight Weenie Ebike

Postby dogman dan » Mon Jul 06, 2015 6:45 am

There you go, sliding down that slippery slope towards a 40 pound bike. But hey, 40 pounds is plenty light for an ebike! Still beats starting with a 40 pound frame, if you want it lighter. Interesting the Bafang is just as light as a cute though.

In the end, you'll have a great bike, with a lighter than usual frame. Not bad, hopefully the frame has ride characteristics you love. Me, I love a nice springy steel frame with lots of side to side stiffness best.

55 pounds works good for me, 35 pound FS bike, 12 pounds hub motor and controller, 8 pound battery. Pretty rideable, though not near as nimble as a naked FS bike in the dirt.
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Re: Weight Weenie Ebike

Postby arkmundi » Mon Jul 06, 2015 7:07 am

LewTwo wrote:Reality is beginning to set it :roll: I spent most of the weekend building a spread sheet for all the parts ..... attached the spread sheet file to this post for anyone that might be interested.

Kudos! More ES'ers would do well to start out with their goals and model it with data before hitting the buy button. Would save a lot of headaches (or worse-aches) if they did. Best of good fortune with your build!
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Re: Weight Weenie Ebike

Postby MadRhino » Mon Jul 06, 2015 8:11 am

dogman dan wrote:55 pounds works good for me,... Pretty rideable, though not near as nimble as a naked FS bike in the dirt.

Hey, 55 Lbs ebike powered 10 Kw is a pretty good weight weenie. It does fly up the hills faster than it was going downhill before having a motor. :twisted:
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Re: Weight Weenie Ebike

Postby Drunkskunk » Mon Jul 06, 2015 1:22 pm

I found a wrinkle in your Cute plans. The fork you have chosen isn't appropriate for use with a motor. You need steel fork for a front motor. Some of them can be very light weight, but heavier than the aluminum fork. I also didn't see torque arms listed. Their weight isn't insignificant. You need at least 1, you should use 2 on a front motor.

You can also shave a few hundred grams by going with a 28 spoke front and 32 spoke rear wheel if you use the BBS01.

You don't need the brake switches, so you can eliminate the wiring weight, and go with a better lighter brake pull.
Tektro brakes are best left alone. There are lighter options. There are better options.
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Re: Weight Weenie Ebike

Postby LewTwo » Mon Jul 06, 2015 2:24 pm

Drunkskunk wrote:I found a wrinkle in your Cute plans. The fork you have chosen isn't appropriate for use with a motor.
I am kind of asinine on keeping the original mating frame and fork. Agreed Aluminum forks are not optimum. However there of plenty of examples of small 250 watt motor being used successfully with Aluminum forks --- even commercially (Schwinn). I do agree that torque arms are well advised even with a steel fork (Schwinn did not use any). I will add them into my spreadsheet.That is one way in which the BBS01 simplifies the build process: torque arm/washer problem goes away.

Drunkskunk wrote:You can also shave a few hundred grams by going with a 28 spoke front and 32 spoke rear wheel if you use the BBS01.

I also want to use the same rims on both my ebikes. The 'grocery getter' has a GM front hub hence 36 spokes. I am anal retentive about matching front and rear rims/spokes. If I were to do that I would use 32 front and back but it only saves 60 grams (90 for 28/32). Aluminum nipples are another thought.

Drunkskunk wrote:You don't need the brake switches, so you can eliminate the wiring weight, and go with a better lighter brake pull.
Tektro brakes are best left alone. There are lighter options.

Most of the work was digging out something with a number I could stick in the 'grams' column. An 'X' in the 'actual' column indicates something I had on hand and could get the weight directly. In fact the Tektro calipers would have too long a reach.

I was trying to get to a starting point where I could compare weight difference of 'apples' and 'oranges' in the same bushel basket. Items that are included in all build versions do not affect the delta. When I had some doubt I went a bit heavy (engineering background: always use worst case scenario). I need to go through and optimize the component selection: brakes, levers, chain, tubes, tires. I think that the reality may be under 30 pounds ... but validating that is months away.
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Re: Weight Weenie Ebike

Postby Spanglo » Mon Jul 06, 2015 7:02 pm

http://www.keyde.com/?do=product&lang=en&event=view&ids=119

9.5 pounds kit including the battery. The integrated controller is a nice, although many say it's a poor design.

Very little feedback tho, and what little is out there is quite bad.

I have a 21 lbs mtb that I would like to keep light. Trying to convince myself that the Keyde is would fit the bill, but I've been receiving resistance whenever ask for opinions or feedback about the motor.

Going to default to the BBS02 in a couple weeks if the Keyde risk factor puts me off.

Thanks for that spreadsheet.
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Re: Weight Weenie Ebike

Postby LewTwo » Mon Jul 06, 2015 8:11 pm

Spanglo wrote:9.5 pounds kit including the battery.
The integrated controller is a nice, although many say it's a poor design.
For my last build (grocery getter) I used the Golden Motors Smart Pie front wheel with the built in sine wave controller. One can program it to use any 24, 36 or 48 volts as well as number of other parameters. I figured that it was flexible enough I could not make a mistake. Wrong: It would not physically fit between the suspension forks uprights on my Schwinn Sierra so I got a temporary bike/frame. No problems with the controler but is quite a bit heavier.

Spanglo wrote:Thanks for that spreadsheet.
Hope that you find it useful.
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Re: Weight Weenie Ebike

Postby Chalo » Mon Jul 06, 2015 8:33 pm

LewTwo wrote:For my last build (grocery getter) I used the Golden Motors Smart Pie front wheel with the built in sine wave controller. One can program it to use any 24, 36 or 48 volts as well as number of other parameters. I figured that it was flexible enough I could not make a mistake. Wrong: It would not physically fit between the suspension forks uprights on my Schwinn Sierra so I got a temporary bike/frame.


It sounds like your mistake was in the choice of bike and/or fork. You must not have been paying attention when any number of us pointed out that suspension forks and front hub motors don't play well together. Fortunately, real forks are not expensive and are usually easy to install after removing the problem part.
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Re: Weight Weenie Ebike

Postby LewTwo » Mon Jul 06, 2015 10:36 pm

Chalo wrote:You must not have been paying attention when any number of us pointed out that suspension forks and front hub motors don't play well together.
I have heard that.
This is Schwinn Tailwind ...
schwinn-tailwind-electric-bike-03.jpg

with a 24 Volt 250 watt (450 peak) motor (Tongxin I think) at a MSRP of $3,200 (circa 2009).
Edit: Yet another correction ... seems Schwinn started development with the Tongxin but switched to using Suzhou Bafang Motors for production.
schwinn-tailwind-electric-bike-01.png

Sorry ... I got the models mixed up:
Reference: http://evsroll.com/Schwinn_Electric_Bicycle.html
schwinn-electric-bike-prices.gif
schwinn-electric-bike-prices.gif (8.83 KiB) Viewed 1141 times

There are several of these currently being sold as NOS on EBAY at $350 (includes shipping).
The catch is that the battery packs are bad.


No torque arms and a similar fork as my Sierra.
Last edited by LewTwo on Tue Jul 07, 2015 12:58 am, edited 2 times in total. View post history.
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Re: Weight Weenie Ebike

Postby mfj197 » Tue Jul 07, 2015 7:15 am

Spanglo wrote:http://www.keyde.com/?do=product&lang=en&event=view&ids=119

9.5 pounds kit including the battery. The integrated controller is a nice, although many say it's a poor design.

Very little feedback tho, and what little is out there is quite bad.

I have a 21 lbs mtb that I would like to keep light. Trying to convince myself that the Keyde is would fit the bill, but I've been receiving resistance whenever ask for opinions or feedback about the motor.

Going to default to the BBS02 in a couple weeks if the Keyde risk factor puts me off.

Thanks for that spreadsheet.

Actually that kit is 4.3kg (9.5 pounds) including the mains charger - the stuff on the bike weighs 3.7kg (8.15 pounds). That makes it reasonably similar to the guessed weights for the Q100 in the spreadsheet. However the battery is 9.3Ah rather than 5Ah and includes mounting weight, whereas I suspect the 1kg quoted by EM3EV for the 10s2p pack does not (the cells alone come to 876g).

This is also rear drive so doesn't mess with the forks. Couple that with something like a Shimano Sora double chainset / bottom bracket at 855g total (compared to the Sunlite in the spreadsheet at 1,600g) and then the hub motor option is coming in at 12.87kg (28.4 pounds). The difference between hub and mid drive is then nearly 1.6kg (3.5 pounds), and it has a much larger battery capacity.

Having said all of that - I'm not sure I'd go with the Keyde myself because of the reports of reliability issues. However the weight of a Q75 front hub is only 1.2kg - do a lightweight build with that (use the Sora crankset for example, and use Vittoria Voyager Hyper 32mm tyres) and suddenly you're down to 11.7kg (25.8 pounds). Take off the mirror and you'd save another pound on that.

(By the way, I'm not sure what your "Remove outer chain Ring from Crank set)" saving 100g is - and it's on all versions, including the Bafang which doesn't have an outer chainring)

Spanglo, there is a huge difference in power and weight between a Keyde and a BBS02 (which needs 48V batteries). The BBS01 LewTwo is looking at here is sort of the half way house between the two.

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Re: Weight Weenie Ebike

Postby LewTwo » Tue Jul 07, 2015 12:51 pm

mfj197 wrote: This is also rear drive so doesn't mess with the forks.
That is why they make vanilla and chocolate. Personally all other things being equal I prefer a front hub motor over a rear hub motor. One of the reasons is that I also prefer an IGH to a Derailleur setup. I was surprised to learn the that the IGH could be as light as the 2x8 Derailleur. I will grant you that it has a much smaller range but that range can 'moved' by simply changing a sing rear cog (16-22 teeth). I suspect that a BBS02 and a Shimano 8 speed Alfine IGH would make a very nice pairing ... it would also be about 1.1 Kg (2.5 pound) heavier than the BBS01 and Nexus Inter3 IGH.

mfj197 wrote: I suspect the 1kg quoted by EM3EV for the 10s2p pack does not .... include mounting weight.
Correct. I figured to put it in a small bag under the seat. My thoughts are that if I need or want more range then I simply use a seat post rack to temporarily hold my HEAVY Golden Motor 36 Volt 12 Ah battery pack and move the connector cable. The 4.9 Ah pack under the seat then becomes a reserve. Than could make for a very good range.

mfj197 wrote: ... a Shimano Sora double chainset / bottom bracket at 855g total (compared to the Sunlite in the spreadsheet at 1,600g) ...
OK, I admit it. Between all the marketing hype and acronyms I was getting frustrated trying to sort out which FSA crankset and BB combinations would fit in a standard 68 mm wide British treaded frame. The Sunlite was a convenient alternative somewhere between the ultra expensive featherweight FSA Carbon fiber crankset and the ridiculously heavy Sunlite steel option (and I knew it would fit). I think that the FSA Gossamer Pro might be a valid alternative as well. Both it and the Sora come in closer to 900 grams with the matching bottom bracket.

mfj197 wrote:However the weight of a Q75 front hub is only 1.2kg
I rejected the Q75 because it is a sensorless and only 200 watts.

mfj197 wrote: ... use Vittoria Voyager Hyper 32mm tyres) ...
Excellent suggestion. I like the low resistance tread pattern as well. I used the Kenda because I just happened to have new one near my scale. Thank thee

mfj197 wrote: Take off the mirror and you'd save another pound on that.
One has to make allowances for self preservation and in my neighborhood the mirror is an absolute necessity.

mfj197 wrote: (By the way, I'm not sure what your "Remove outer chain Ring from Crank set)" saving 100g is - and it's on all versions, including the Bafang which doesn't have an outer chainring)
It was intended to be a lazy way to get to a single speed crankset for the IGH. It is included in the BBS01 version because I screwed up. :oops:

mfj197 wrote: ... a BBS02 (which needs 48V batteries).
Actually I believe it is available as a 36 volt unit as well.

Seems that I need to do some work on my spread sheet.
Does anyone know what the actual weight for 36 volt 15 Amp Square Wave controller is?
Recommendations would be appreciated.
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Re: Weight Weenie Ebike

Postby Spanglo » Tue Jul 07, 2015 3:12 pm

mfj197 wrote:Actually that kit is 4.3kg (9.5 pounds) including the mains charger - the stuff on the bike weighs 3.7kg (8.15 pounds). That makes it reasonably similar to the guessed weights for the Q100 in the spreadsheet.

Spanglo, there is a huge difference in power and weight between a Keyde and a BBS02 (which needs 48V batteries). The BBS01 LewTwo is looking at here is sort of the half way house between the two.
Michael


Thanks for clarifying the kit weight... looks even better. I agree also, the Keyde reliability is too questionable to consider at the moment.

The BBS02 is reported to run well @ 44V. I'm planning on run 12S 6.6Ah pack using two 6S 6.6Ah lipos in series in a seatpost bag. Pack weight at 1.6kg.
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Re: Weight Weenie Ebike

Postby cwah » Wed Jul 08, 2015 12:10 am

how can a Q100 add 3.8kg? At most we have:
Q100: 2.2kg
Torque arms: 0.2kg
Controller: 0.3kg
Wiring & display: 0.3kg

So total 3kg. How did you count that?
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Re: Weight Weenie Ebike

Postby LewTwo » Wed Jul 08, 2015 12:20 am

cwah wrote:how can a Q100 add 3.8kg? At most we have:
Q100: 2.2kg
Torque arms: 0.2kg
Controller: 0.3kg
Wiring & display: 0.3kg

So total 3kg. How did you count that?
Battery = 1 Kg

I have been fine tuning the spread per some of the comments above. Attached is the revised version.
Changes: BB, crankset, chain, tires
Weight Comparison(new).png
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Re: Weight Weenie Ebike

Postby Jasonv8z » Wed Jul 08, 2015 1:28 am

I just finished a carbon 29er/q100H rear drive build. Was 24# with the motor, 38mm tires, platform pedals, and fairly low end components. 29.7# With 12S 5ah batteries (because I didn't have 13s), 6s controller, display, throttle, and frame bag. I use it for an 8 mile commute with hills, and use less than 50% capacity. I can cruise around 28mph if I pedal hard enough to get a good workout.
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Re: Weight Weenie Ebike

Postby LewTwo » Wed Jul 08, 2015 1:45 am

Jasonv8z wrote:I just finished a carbon 29er/q100H rear drive build. Was 24# with the motor, 38mm tires, platform pedals, and fairly low end components. 29.7# With 12S 5ah batteries (because I didn't have 13s), 6s controller, display, throttle, and frame bag. I use it for an 8 mile commute with hills, and use less than 50% capacity. I can cruise around 28mph if I pedal hard enough to get a good workout.
Interesting.
Did you use the high speed or low speed Q100H motor?
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Re: Weight Weenie Ebike

Postby bowlofsalad » Wed Jul 08, 2015 6:23 am

One has to make allowances for self preservation and in my neighborhood the mirror is an absolute necessity.


http://www.amazon.com/gp/product/B001VT ... SO2ODGOPMC Radically less weight, better viewing angle and excellent aerodynamics. I just weighed them, one of my scales doesn't register them at all, another scale just barely moves the needle, maybe 10 grams weight, probably a little less. I actually didn't realize how light they were myself, I always just really liked these because they work super well.

I'd probably recommend the Q100h to you but I'd go with the rear. I don't like all the messing around with the front forks, you need torque arms either way, but I'd go with doctorbass torque arms. They are (probably) lighter, cheaper, and allow easier installation and removal of the wheel once they are setup. viewtopic.php?f=31&t=29129
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Re: Weight Weenie Ebike

Postby LewTwo » Wed Jul 08, 2015 9:00 am

bowlofsalad wrote:I'd probably recommend the Q100h to you but I'd go with the rear. I don't like all the messing around with the front forks, you need torque arms either way, but I'd go with doctorbass torque arms.


Kind of challenging to mount Q100h and an IGH on the same wheel :lol:
You are right about the doc's torque arms/washers ... in fact I should have had them in the spreadsheet. :oops:

Edit:
Just measured the fork. The diameter of his torque arms is 50.8 mm (2 inches) = 25.4 mm radius.
The flat area of the front dropouts is only about 16 mm to the point where a 45 degree angle mates to the rest of the fork.
I will have to revert ot something like this ...
PlanC-4(detail).JPG
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Last edited by LewTwo on Wed Jul 08, 2015 9:46 am, edited 1 time in total. View post history.
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Re: Weight Weenie Ebike

Postby mfj197 » Thu Jul 09, 2015 8:44 am

Some interesting discussion. I think we're moving away from the idea of a "weight weenie ebike", the ethos of which is a bike as lightweight as possible. E-Zero's FX-E singlEspeed on this forum (link here) is a true example of a weight weenie at 12kg based on a Q100 and with a 10S 5Ah battery. Not to mention it's a beautiful bike to look at too. Singlespeed makes quite a lot of sense with a hub motor.
LewTwo wrote:I suspect that a BBS02 and a Shimano 8 speed Alfine IGH would make a very nice pairing ... it would also be about 1.1 Kg (2.5 pound) heavier than the BBS01 and Nexus Inter3 IGH.

Which puts it at well over 15kg, using just sidepull caliper brakes, and with a battery life of under 12 minutes at full power. That sort of weight is already pretty significant which is why most people building bikes with that sort of power and weight don't skimp on the battery - for the sake of an extra 1kg (6.5% weight increase) you double the range.
Lewtwo wrote:I rejected the Q75 because it is a sensorless and only 200 watts.

But why is more power needed? "Only" 200 watts is actually a goodly amount of power for a cyclist. I ride my BBS01 on about 250W all the time (it'll do over 500W) and I'd happily trade the unused extra power for lightness - and this is on a 40 mile per day commute at 20mph average. One really doesn't want to be pushing too much power when only using caliper brakes to slow down anyway (I'm guessing your frame/forks preclude discs?).
LewTwo wrote:
mfj197 wrote: ... use Vittoria Voyager Hyper 32mm tyres) ...
Excellent suggestion. I like the low resistance tread pattern as well. I used the Kenda because I just happened to have new one near my scale. Thank thee

You're welcome - they are great tyres. If your frame will take them look at the larger sizes. I use the 40mm versions which have even less rolling resistance (wider versions of the same tyre roll better), are significantly more comfortable and puncture resistant and provide even more grip. They are still only 450g each.
LewTwo wrote:
mfj197 wrote: ... a BBS02 (which needs 48V batteries).
Actually I believe it is available as a 36 volt unit as well.

Yes indeed, a 500W version. I personally wouldn't use it - I'm running at about 10A limit on the controller and don't feel the need for 25A as I like the feeling of riding a bike rather than a motorbike. With 10A pedalling still makes a significant difference and I can change gear without fear of crunching the gears on the rear deurailleur.

My own conversion which I linked to earlier is similar to a lot of your thinking. I started with a 10.9kg bike (versus your 9kg) but with hydraulic disc brakes, and the BBS01 conversion took it to 18kg. That 6.9kg increase included a 2kg battery pack held inside a 400g saddlepack.

Hope those ramblings are of some use! :)

Michael
mfj197
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Re: Weight Weenie Ebike

Postby Jasonv8z » Thu Jul 09, 2015 2:36 pm

LewTwo wrote:
Jasonv8z wrote:I just finished a carbon 29er/q100H rear drive build. Was 24# with the motor, 38mm tires, platform pedals, and fairly low end components. 29.7# With 12S 5ah batteries (because I didn't have 13s), 6s controller, display, throttle, and frame bag. I use it for an 8 mile commute with hills, and use less than 50% capacity. I can cruise around 28mph if I pedal hard enough to get a good workout.
Interesting.
Did you use the high speed or low speed Q100H motor?


I used the 260 wind.
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Re: Weight Weenie Ebike

Postby Alex W » Fri Jul 10, 2015 1:42 am

I'd recommend riding a PAS bike (which is what the BBS0* builds up into) vs a torque sensor bike to see which you prefer. I've ridden both and greatly prefer the natural riding feel of a torque sensor bike. I have friends who prefer the moped feel of a PAS bike. They are very different.

The only downside of the torque sensor bike is that you do get a fair amount of lag (it feels like a car with terrible turbo lag) due to sampling the torque once or twice per pedal revolution. It would be nice if the CAv3 did something smart here, like remembering the wattage output after the first pedal revolution from your last dead start and ramping up into that.
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Re: Weight Weenie Ebike

Postby mfj197 » Fri Jul 10, 2015 6:01 am

Alex W wrote:I'd recommend riding a PAS bike (which is what the BBS0* builds up into) vs a torque sensor bike to see which you prefer. I've ridden both and greatly prefer the natural riding feel of a torque sensor bike. I have friends who prefer the moped feel of a PAS bike. They are very different.

The only downside of the torque sensor bike is that you do get a fair amount of lag (it feels like a car with terrible turbo lag) due to sampling the torque once or twice per pedal revolution. It would be nice if the CAv3 did something smart here, like remembering the wattage output after the first pedal revolution from your last dead start and ramping up into that.

Which torque sensing system did you ride? The Bosch generation 2 that I tried was instant - indeed an advantage of a decent torque sensing system is that the pedals don't need to be turning at all for it to measure and register torque input and therefore start providing proportional assist current. Bafang were going to produce a torque-sensing version of the BBS01 (called the BBT01) but it hasn't made it to market yet, even after a couple of years.
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