Newbie considering an e-conversion. But what.

[vfr400]

@vfr400 Sorry, don't see it. There is no way a poxy little 250w motor can multiply the force a grown man standing on the pedals on the drive chain by a factor of 4. It's just nonsense.
@sjpt is much nearer the mark when he says it can consistently increase the load, that makes much more sense.

See the table about 1/3 the way down - support level%:

Velorution: It's Time to Ride in Style

velorution.com

 

[vidtek]

See the table about 1/3 the way down - support level%:

Velorution: It's Time to Ride in Style

velorution.com

Exactly - Max torque 85nm. I wouldn't mind betting the torque a grown man puts on the crank will be at least 5-10 times that when stood up and pushing hard.

 

[Woosh]

Exactly - Max torque 85nm. I wouldn't mind betting the torque a grown man puts on the crank will be at least 5-10 times that when stood up and pushing hard.

Torque a cyclist can push on the cranks by just standing on the pedal:

crank arm length: r = 0.175m
rider's weight: w = 80kgs
gravitational acceleration constant: g = 9.81
Torque = r * w * g = 0.175 * 80 * 9.81 = 137NM

Athletes can of course push much more than that.

 

[vidtek]

Torque a cyclist can push on the cranks by just standing on the pedal:

crank arm length: r = 0.175m
rider's weight: w = 80kgs
gravitational acceleration constant: g = 9.81
Torque = r * w * g = 0.175 * 80 * 9.81 = 137NM

Athletes can of course push much more than that.

137nm --- And that is just standing on them with a lightweight rider--if you are a heavy person ---well!

 

[vfr400]

137nm --- And that is just standing on them with a lightweight rider--if you are a heavy person ---well!

Exactly - Max torque 85nm. I wouldn't mind betting the torque a grown man puts on the crank will be at least 5-10 times that when stood up and pushing hard.

You're taking a worst case example. If you rode everywhere standing on the pedals with 137nM, I can gaurantee that you'll be replacing drive train components just the same as with a crank drive. We're talking about the difference between a leisure cyclist, cycling with an average input of 60w to 100w compared with a motor that can put out anything up to 400w with the cyclist adding their 100w too, so the difference can be as high as 500w vs 100w at the crank. That's for a 36v 15A typical 250w crank-drive. When you go up to 48v and 25A, it's the difference between 100w and 900w.

The wear rate on steel parts is more or less in direct proportion to surface load, so standing on the pedals, where most people can get up to about 800w for a short time, compared with riding at a more normal 100w, will wear 8 times as quickly. Your argument seems to be that a crank motor can't wear a drive train faster than a cyclist riding normally because the cyclist can pedal as hard as a crank motor for a short time - as if pedalling harder doesn't wear things faster. That's complete nonsense. You only have to apply basic logic.

The table that I showed you indicates the assistance factor for each motor and each setting. That's how much it multiplies the input torque as a percentage. You can't get simpler than that - no need to calculate anything, but don't forget that when it says assistance 300%, it means your 100% +300% = 400% compared with 100% without assistance, so it's actually a factor of 4 times the force and stress on the chain. Just to make that clear, as you don't seem to have a good understanding of some things: When you pedal with 10Nm, the motor gives 300% assistance (when it says 300 in the table), so you get 10 +30 = 40Nm.

For info, pedalling at 60w requires a torque of approx 10Nm on the crank, or exactly 15.9167 Nm for 100w.

 

[Woosh]

You're taking a worst case example. If you rode everywhere standing on the pedals with 137nM, I can gaurantee that you'll be replacing drive train components just the same as with a crank drive. We're talking about the difference between a leisure cyclist, cycling with an average input of 60w to 100w compared with a motor that can put out anything up to 400w with the cyclist adding their 100w too, so the difference can be as high as 500w vs 100w at the crank. That's for a 36v 15A typical 250w crank-drive. When you go up to 48v and 25A, it's the difference between 100w and 900w.

The wear rate on steel parts is more or less in direct proportion to surface load, so standing on the pedals, where most people can get up to about 800w for a short time, compared with riding at a more normal 100w, will wear 8 times as quickly. Your argument seems to be that a crank motor can't wear a drive train faster than a cyclist riding normally because the cyclist can pedal as hard as a crank motor for a short time - as if pedalling harder doesn't wear things faster. That's complete nonsense. You only have to apply basic logic.

The table that I showed you indicates the assistance factor for each motor and each setting. That's how much it multiplies the input torque as a percentage. You can't get simpler than that - no need to calculate anything, but don't forget that when it says assistance 300%, it means your 100% +300% = 400% compared with 100% without assistance, so it's actually a factor of 4 times the force and stress on the chain. Just to make that clear, as you don't seem to have a good understanding of some things: When you pedal with 10Nm, the motor gives 300% assistance (when it says 300 in the table), so you get 10 +30 = 40Nm.

For info, pedalling at 60w requires a torque of approx 10Nm on the crank, or exactly 15.9167 Nm for 100w.

by the same comparison, most people don't go much faster on electrics than they did years ago on their non-motorised bikes when they were younger.
The loading and corresponding wear and tear are proportional to the total amount of energy which in turn proportional to speed (cubed) and mileage, have not grown much because of crank drive.
How many needs new chain, new cassette or new chain rings? I guess about 10%.

 

[vidtek]

@vfr400 We are not going to agree on this. Let's move on, and take Whoosh's answer as definitive.

 

[vfr400]

by the same comparison, most people don't go much faster on electrics than they did years ago on their non-motorised bikes when they were younger.
The loading and corresponding wear and tear are proportional to the total amount of energy which in turn proportional to speed (cubed), has not grown much because of crank drive.
How many needs new chain, new cassette or new chain rings?

That's not true. We know exactly the contribution of the motor by how much battery is used, so for any journey, you can calculate the average power. Anecdotally, the average ebike usage is around 12wh/m at an average speed of about 12 mph, which is about 144 watts continuous. With 70% conversion efficiency, that's 100w . Lets take 80w as an average leisure cyclist, so the overall average increase in wear rate is 180w vs 80w = 2.2.

Have a look in your consumption calculator tool. It's simple to calculate the increase wear rate from that, like I did above.

Wear rate factor = 1 + watts per mile x 0.7 x average speed/80

 

[vidtek]

That's not true. We know exactly the contribution of the motor by how much battery is used, so for any journey, you can calculate the average power. Anecdotally, the average ebike usage is around 12wh/m at an average speed of about 12 mph, which is about 144 watts continuous. With 70% conversion efficiency, that's 100w . Lets take 80w as an average leisure cyclist, so the overall average increase in wear rate is 180w vs 80w = 2.2.

Have a look in your consumption calculator tool. It's simple to calculate the increase wear rate from that, like I did above.

Wear rate factor = 1 + watts per mile x 0.7 x average speed/80

Blimey, you're like a dog with a bone - let it go mate, life's too short. Chill out with a cold beer.

 

[vfr400]

Blimey, you're like a dog with a bone - let it go mate, life's too short. Chill out with a cold beer.

I've been on this forum for 11 years and made over 30,000 posts. Who made you the president of Pedelecs.co.uk, so you can tell people what and when to post? It seems that you just don't like to be wrong. When it's pointed out, you throw a tantrum. Anyway, I'll continue to post what I want when I want until the lovely Helen or the nice bloke Russ tells me not to.

 

[vidtek]

This is silly, it's a forum for all and it's best to maintain a friendly conversation, I had no intention of bruising your enlarged ego, just trying to bring some common-sense perspective to the discussion; no tantrums from me, I'm chilling out in my garden with a cold beer enjoying the birdsong and the smells emanating from the kitchen, dinner will be served shortly.

 

[Woosh]

Anecdotally, the average ebike usage is around 12wh/m at an average speed of about 12 mph, which is about 144 watts continuous. With 70% conversion efficiency, that's 100w . Lets take 80w as an average leisure cyclist, so the overall average increase in wear rate is 180w vs 80w = 2.2.

if you reckon on 144W continuous, then that's what goes on the drive train, it does not matter much whether some or most of them comes from the motor.
I reckon the average mileage for leisure cycling is about 1,000 miles a year. At this rate, the drive train would outlast the electrics.

 

[vfr400]

if you reckon on 144W continuous, then that's what goes on the drive train, it does not matter much whether some or most of them comes from the motor.
I reckon the average mileage for leisure cycling is about 1,000 miles a year. At this rate, the drive train would outlast the electrics.

But they don't last very long as most crank-drive owners know. A250w crank drive will wear the chain and cassette about 3 to 4 times faster than with a hub-drive. Ask anybody that's tried both. Sure, if you park your bike in the garage and never use it, it'll last forever as long as you keep it oiled where necessary. What does that prove? It's the same as the guy who rides his crank-drive bike everywhere with his power switched off and argues that his doesn't wear any faster than a normal bike.

 

[Deno]

My own experience - 3000km on my chain on a dongled bosch CX and its just started skipping. Thats the best I've seen, usually its 2500km before it needs to be swapped. Takes me 30min to swap crank / chain / cassette along with greasing the motor etc. and it costs 50eur so I'm not bothered. I prefer crank drive to hub, its just a personal preference but in saying that I haven't tried a hub drive in a while - maybe they've improved.

 

[Woosh]

I prefer crank drive to hub, its just a personal preference but in saying that I haven't tried a hub drive in a while - maybe they've improved.

there is little difference in feels beside the weight of the motor in the wheel.
Once you get up to speed, I reckon you'll stop thinking about them.

what hub drives need is someone does an OSF project like the one for the Tongsheng TSDZ2. Hub kit controllers need a more refined, user programmable starting off acceleration and smooth cut out at 25kph.

 

[Tony1951]

@vfr400 Sorry, don't see it. There is no way a poxy little 250w motor can multiply the force a grown man standing on the pedals on the drive chain by a factor of 4. It's just nonsense.
@sjpt is much nearer the mark when he says it can consistently increase the load, that makes much more sense.

My comments regarding MY set up, are about fluffed gear changes while the motor is hauling. My conversion does not have a gear change cut off switch and now and then, I do my cutomery momentary relax in pressure as I change up or down, but after a lifetime of bike riding, habits die hard and my automatic, muscle memory does not allow enough time for the motor to shut off and stop hauling on the chain. It keeps hauling for a good second after I stop pedalling. This leads sometimes to clunking, nasty changes as the chain swaps cogs under strong pressure. The 'poxy little 250 motor' as you so colourfully describe it, might actually be consuming a shade over 500 watts at these times so it might be at that moment pulling 400 watts. I think I have seen about 600w on the screen. I can't speak to how much force Lance Armstrong or his fellow athletes put on their cogs, but they are probably not hauling almots 2/3ds of a horsepower as the chain crunches over the rear sprocket teeth onto another cog. THAT is what my post was about really. The noise is a clear indicator of a potentially damaging event. Of course - as you will no doubt be thinking - 'Drive it better then you clown'. You would be right of course. I could also make a better job of the installation and fit a gear change sensor. I think the controller has a wire for it.

Ordinary wear when not chnaging gear is less worrying to me at least.

 

[RichD1]

One can get a lot of exercise out of a hub motor e bike as one can a mid drive, you choose the appropriate controller system that enables one to do so.

You mention the KT advanced controller systems, but do all kits from Woosh need this or are the kit controllers good enough?

I'm swaying toward a DWG22C or XF08 CST

 

[Nealh]

Woosh are/were using Lishui controller still however whether they are speed or current control you will have to ask Tony.

 

[vfr400]

what hub drives need is someone does an OSF project like the one for the Tongsheng TSDZ2. Hub kit controllers need a more refined, user programmable starting off acceleration and smooth cut out at 25kph.

It's called a KT controller. I've been telling you to change for years. with KT you also get a legal throttle that gives independent start to 4mph and continues up to the speed limit as long as the pedals rotate. Most other controllers can give you one or the other, but not both at the same time.

 

[cannon]

I would like to add my experience.
Living in Wales and doing some off road I went for a mid drive BBS01 on a mtb, a gear change sensor was added to smooth gear changes and give the chain an easier time (essential IMHO). After 1500 miles with this setup the BBs01 motor was transferred to a hybrid bike and a BBS02 500w fitted to the mtb, but keeping the original chain and sprockets.
The mtb has now done 2000 miles. Yesterday I measured the chain pitch with a vernier caliper and the stretch was 0.25% which I believe is half the recommended wear limit of 0.5%. Even if the measurements were off slightly I am more than happy with this wear rate.
The chain is frequently cleaned and lubed but also endures bursts of full power when up hill off road. I am expecting chain on the hybrid bike with the 250w motor to last even longer as it will be road use only.