[Closed] Single speed ebike

Someone will know better but I'm not sure it's a good idea to run an eeb on single speed as the motors work best at a certain cadence.

Grinding up a hill in a stiff gear would I think put undue stress on the motor.
It's a motor sure, but still needs mechanical sympathy.

Same as unassisted single speed, you'll have the perfect gear for about 10% of the time 😂

Well were have to collate a few replies, my motor works on those 5 bar settings & works from the outset & increases torque i assume with each bar so im hoping only a little practice will have the ability to set the bar level undulating relative & including gear ratios to have a low maintenance fun bike until the motor goes & then sold spares or repairs with the new but ' old ' parts.

Its only done about 300 miles max.

Thanks for reply, lets hope others might agree or dispute, but that's the point of the thread ! & forums.

Seen a few ebikes in the shop where people have just left it in a big gear and used the motor to boost it. Wears components and stuff very fast as under a lot of force, unless you have a fairly flat ride you might find issues further down the road. Pun fully intended.

I rode my tongsheng kit single speed for a short while ( BB mount kit)  worked better than I thought it would as I found I was only using a couple of gears anyway.

With a hub motor you are not altering the stress the motor is under as the motor is after any gearing not before so the hub is turning at road speed not pedal speed

Grinding uphill at low speedis where BB mount motors work much better than hub mount motors.  I think the only issues you will need to watch for are reduced range with the high torque / low revs of a hub motor turning slowly and also the risk of the motor getting hot but this remains the same geared or not for hub motors

I wouold go lower gears than you intend tho.  2:1 as that should be spinning along nicely at 15 mph when the boost cuts and be low enough to climb at a halfway decent cadence

Hope that helps

alll IMO of course

Someone will know better but I’m not sure it’s a good idea to run an eeb on single speed as the motors work best at a certain cadence.

More than I expected: https://electricbikereview.com/forums/threads/interesting-read-about-the-nature-of-ebike-motor-and-efficiency.15652/

You could always change the final gearing of the motor to improve efficiency at lower cadences.

Ours (Tongsheng mid drive) are set up single speed (42:17 on 26" wheels, was 42:21 but that was too spinny), the assist cuts out at 25km/h which is a nice cadence just to keep it wiffling along on leg power, any hint of a hill or headwind and the assist cuts in (gently) to help you back up to leg power. So far we've done ~40 miles and counting on one charge on a mix of 'tour' and 'sport' modes. I wanted to set the bikes up for long-ish range potterings and so far they're doing what we wanted them to do. It is fairly flat around here (east Durham) though and easily singlespeedable (is that a word?) anyway so that probably helps with the range and stuff.

The OP is a hub motor from my reading of his post

Yeah, I know, I just wanted to chime in with our experience of single speeded e-bikes, just like you did 😁 Cheers for the pointer though.

With a hub motor you are not altering the stress the motor is under as the motor is after any gearing not before so the hub is turning at road speed not pedal speed

Not sure I understand this. The road speed is slower due to the incline and the load is greater because it's an incline.
Might be being thick but how is it not under more stress?
I get that the hub gear is after the crank gear, but it's still trying to push the same load and wheel up an incline instead of the flat.
It has to put in more oomph and therefore more strain to maintain movement Shirley?

its under the same stress no matter the gearing because the hub is after the gearing thus the motor turns at road speed not pedal speed

yes stress increases as you climb but the gearing does not change this.  climbing a 30% hill at 5km/ hr the motor is turning the same low revs no matter if you are peddling at 30 rpm or 70 rpm

Grinding/lugging/high load & low revs in a motor results in heat build up which ultimately damages the motor. Better to keep them spinning using gears with higher revs/lower loads to help longevity. This goes for all ebikes

yes stress increases as you climb but the gearing does not change this

No, the incline does.
So the same road speed but with different gears would not change stress load, but we're not talking a static environment so even with a hub gear it's still putting undue stress on, no?

Yes

But for the OP it matters not what the gearing is.  the motor is turning at road speed not pedalspeed so going SS does not alter anything for the motor

the motor is under the same stress if he is running a low or high gear

Does the person doing the pedalling not have any say in how hard the motor has to work?

NOt really with a cadence sensor motor.  I suppose if the rider is putting out a lot of power you will be climbing a bit faster than if they are not and that would put the motor at slightly higher revs but with a cadence sensor motor the amount of power the rider puts in does not change the amount of power the motor puts out

Oh, I see, that makes sense, thanks for explaining.

Well i hadn't thought of heat buildup thats good as summers round the corner.

Afaik the hub puts the torque to the motor based on 5 settings, i don't as of yet use the 1,2 settings.

You just have to pedal more, the tensioner states minium 18T & i wondered if 19 would be better for stress loads continually on a 6kg rear hub wheel & if true better still if a higher rear ratio.

I can go 46 on the front & preferable as the chainstay clearance is tight & might be to tight with the new crank.

So ill go 46T crank & im kinda clueless to the rear, but id want at least 20 mph piory spinning out imo or higher, but you can't have it both ways so any suggestion for 46 chainset ref rear, the 2.1 doesn't compute to my ltd maths only 46 front & weather rear should be 20 or more ect.

I take breaks regular on bike & will now use the shade aswell & feel the heat buildup & judge accordingly.

Failing single speed i can get deore groupset 5200 derailer 4100 chainset BB & cassette for 209 £.

Current cheap chainset has moved chainlign about 5 mm outwards & the chain is yet to go on to test it as proberly need new chain shop instal.

& im loathed to spend 100 on a half descent BB & crank alone, when was going to upgrade to shimano U55 built to last to go with the stormy

Bikes getting on my tits tbf, thats 1000£ ebikes their not built for descent cycling, i wasn't expecting the crank & BB to be so God dam poor.

Any suggestions welcome deliberation.

& just had a thought im quite prepared to get two rear cogs would prefer, & wether that stormy cassette removal tool is needed, the freewheel is only like 14 £ est so gladly get two sizes to have a choice.

Hows about 18 & 20 / or 19 22 or perhaps like a 18 & 22 i don't know but both to go with a 46T chainset ?

Thanks

Try this, figure out where you're comfy spinning and gear for that-

https://www.bikecalc.com/speed_at_cadence

I used to run a Bafang mid drive kit single speed for a brief period. I was running a 36/18 ratio which was probably just about right for the hills near me, which gave a good balance between climbing cadence and top speed.

I presume the kit isn't limited to 15.5mph if you're thinking about a 46t chainring. I ran a 46t chainring previously (but geared), but found the top speed to be a bit too 'anti social' unrestricted for where I was riding, hence swapping for a 36t.

Thanks for the chart it makes no sense to me mind !

ive got about 6 cm max clearance from current 46T to the seatstay ref chain so could go to perhaps down as low as 32 i hadnt thought to go lower front , i can look for other cranks, ill have a gander.

& i don't know if a bigger rear cog is better for this bafang rear wheel or if it makes little difference.

Can get the 42T @ 80 odd or the 44T @ 60;£

If that helps any mathematicians

https://www.johnatkinscycles.co.uk/product/150696/sturmey-archer-single-speed-chainset/option/

Well ive found a stormy 42T @ preferred 165 mm for 53 £ & pair it with a ' covidiot ' 19 rear.

Can always go to 18 20 21 if nesasary.

Thanks Forum

S

It looks like you're changing to 1/8" instead of 9 speed. There's no strength advantage in 1/8" and it just restricts choice. I've been singlespeeding for years on 9 spd stuff. And I'm a big unit. The first conversion I did used a cog from a cassette, the middle ring of a triple and a homemade tensioner. Cost zero. My road fixed wheel bike is 1/8 chain but that's because it's ancient and pre-dates 3/32".

The wonders of forums despite a surly troll disappointedly having 26 wheels i opted for 1/8 for twinterweb said strength.

Prefer 3/32 & more choice like thin thick chainset negating need for chainguard.

Opted to upgrade bottom bracket different spindle length to correct chainline.

& the conversion can wait, least now have ' schematics ' known over more purchased in error items.

Thanks sincerely,

Caveat there's a dhf 3C terra fear max WT tyre on ebay for covid 19£ any forum membar can have it for a ' tenor ' its done 8 miles & strictly cash on collection only.

S