eBike gearing??
 

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[Closed] eBike gearing??

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Getting a bit confused by this...

I'm looking at budget eBikes - hardtails with mid-motors (like Cube Reaction Hybrid, Giant Liv Valle-e and so on).

How on earth do you get the right gearing? The variation in cassettes and chainrings seems to be really big, and nothing like non-eBikes of similar type. Most seem to be 1x9, with 32 or 34 teeth chainrings, but with 11-32 up to 11-36 cassettes.

Are the motors really going to help you climb well using 32x32? I'm used to using 22x36 on a 29er for the steepest climbs.

And what's going on with the Bosch motors with an 18 tooth chainring - how can the top end be useful?


 
Posted : 05/11/2018 4:30 pm
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From demos, gear choice on an ebike seems more about how fast you want to go than how steep the hill is. Though presumably you are using more battery climbing in a harder gear.

I'm not sure what's going on with the wildly different chainring sizes, but not having a big cassette is understandable.


 
Posted : 05/11/2018 4:39 pm
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Are the motors really going to help you climb well using 32×32?

Yes


 
Posted : 05/11/2018 4:46 pm
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Well that explains why owners obsess about battery usage - I can't imagine climbing steep hills on a 21kg bike with those kind of gears.

So, how to choose? Trust the manufacturers?


 
Posted : 05/11/2018 4:49 pm
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That or demo some, or change the gearing later if you don't like it...


 
Posted : 05/11/2018 4:57 pm
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Problem is that it's not for me.

This is what's puzzling me (two examples, not bikes I'm trying to choose between)

1x9 with 11-36 and a 15t chainring

https://www.scott-sports.com/fr/fr/product/velo-scott-aspect-eride-40?article=270788269

2x9 with 11-36 and 24/38T chainrings

https://www.liv-cycling.com/int/vall-eplus-2

How can these bikes be in the same category? What am I missing... or am I being silly in thinking that anyone would notice a 23 tooth difference in front chainrings when trying to pedal?


 
Posted : 05/11/2018 5:04 pm
 geex
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My (Shimano motor) 170mm Emtb has 36x11-32 and my 170mm non-Ebike has 32x 10-42 - pretty similar gearing really (because I ride them the same places). On the Eeb average speeds are increased so I spent a lot more time in the smaller sprockets (and why I wouldn't want an XD 10T sprocket). I rarely use the 42T on either bike. on the Eeb when it's switched off (riding with other non-Eebs) or for short super steep loose or wet climbs that would be a serious effort on the non-Eeb. I didn't buy an Ebike to conquer new climbs. infact I can only think of a couple of climbs I've ever done on it I couldn't manage on a non-eeb. I bought it to get more descending in in a shorter period of time.
There's a visual display bar showing how much assist the motor is giving you so you can back off or go full assist by simply altering your own effort/cadence or changing mode. It's pretty intuitive really. (not sure which other motors have something similar (Spesh don't show any display info)

The Bosch motor turns that l'il sprocket at a different RPM to the crank so it's output ratios work out similar to a normal sized single ring


 
Posted : 05/11/2018 5:14 pm
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This is entirely speculation but I'd guess some of these bikes are aimed at casual use. Maybe a tiny chainring helps maximise battery life and keeps things easy for people that wouldn't be riding if it wasn't power assisted, and are never likely to exceed the 15mph cut off.


 
Posted : 05/11/2018 5:16 pm
 geex
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2x is stupid on an Emtb 34x11-36 would be fine on that Liv bike. it has an 80NM motor FFS!


 
Posted : 05/11/2018 5:16 pm
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LOL at these gear ratios once the battery is flat....


 
Posted : 05/11/2018 5:21 pm
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LOL at these gear ratios once the battery is flat….

Kind of seems like complaining about suspension on an MTB because you have to ride home on the road?

I don't think many people will be riding far with the battery flat, and it's not going to be a great experience whatever the gearing.


 
Posted : 05/11/2018 5:25 pm
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And what’s going on with the Bosch motors with an 18 tooth chainring – how can the top end be useful?

The Chainring does not turn at 1 revolution per pedal revolution.

I think it’s 2.5 times per pedal revolution, but I haven’t checked.

Top end on mine before I spin out is about 55km/hr.

Bosch CX mid drive, Yuba spicy curry.


 
Posted : 05/11/2018 5:29 pm
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On an ebike with a bottom bracket mounted motor the cranks are not turning the chain ring directly, there is effectively a gearbox in there. So with the bosch motor with the 15t chain ring it spins roughly twice as fast as the cranks.

The internal ratio is different with the Yamaha and Shimano motors hence the different sprocket sizes.

The manufacturers will have set up the gear ratios so they are all pretty similar and will be roughly equivalent to a 32 front 11:42 setup. You don't need super low gears when you have an additional 250w of power.


 
Posted : 05/11/2018 5:33 pm
 geex
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Actual Laugh OUT loud al? m'kay

Mine rides just like any normal bike but 17lb heavier (ie. no motor drag). I'm not weak so can still climb with those ratios when it's switched off. It just means standing up* while climbing more. My body weight varies by more than that from my leanest to my heaviest.

*My run-a-round hardtail is still a 4X frame with a 32x11-25 cassette so i'm used to it


 
Posted : 05/11/2018 5:34 pm
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I don’t think many people will be riding far with the battery flat, and it’s not going to be a great experience whatever the gearing.

I'm LOLing, not complaining. You can always predict how much of your ride will be on a road.

Some will be using them to go further, I wonder how predictable battery life is.

I’m not weak so can still climb with those ratios when it’s switched off. It just means standing up* while climbing more

Well you do have a bit of an AWESOME reputation 🙂 Plenty climbs where no amount of standing will work on 1:1 with 17lb extra.


 
Posted : 05/11/2018 5:35 pm
 geex
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I don’t think many people will be riding far with the battery flat, and it’s not going to be a great experience whatever the gearing.

Think I did about 15miles and 3000ft+ of climbing recently with my motor switched off for 95% of it. I'd misunderstood that SSStu and MrsSSStu were bringing their Eebs for a ride at the Golfie, they'd been riding every day so it would have been a complete dick move to ride with them the whole day assisted. Apart from one unclimbable section where we split up because I thought the motor could help me ride up a descent which turned out to be unclimbable too even in boost and ended up pushing it up with a little help from "walk assist"

Battery life is completely predictable al. Not from the display (battery level indicators are rarely ever accurate) but from common sense and experience.

A fully charged battery will get me around 4500ft of fire road climbing in Boost or as little as 3000ft of soft natural steep more technical climbing. I can calibrate pretty easily in my head from what i'm riding at the time and waht modes I've been using how that'll pan out.
But you know what? it doesn't really matter because if it runs out I can quite easily still pedal it up another climb or home.


 
Posted : 05/11/2018 5:55 pm
 geex
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Plenty climbs where no amount of standing will work on 1:1 with 17lb extra.

HTF would you know? 😉

I'm not really interested in climbing stupidly steep climbs. and where did I say I used 1:1 ?

it's far less to do with being AWESOME and far more to do with not being a whiney ****


 
Posted : 05/11/2018 5:59 pm
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My experience of ebike with 34x 11-40 is that I don’t need lower gearing as eco or trail mode will get me up anything. Eco alone gets me up all but he steepest sections.

but, I end up using trail mode on sections where I reckon a lower gear and eco mode would get me up it. Which I am guessing would save more battery too.

Also lower gear would be handy if do run out of battery.

so may got for a lower gear in future with an expanded cog.

Still only 3 rides in on the ebike so still learning best compromise between power and battery life.


 
Posted : 05/11/2018 6:24 pm
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Both ours run SRAM 11 speed 10- 42 cassette with XD driver and a 32t front ring. Only tend to run with them in Eco mode


 
Posted : 05/11/2018 6:46 pm
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I've got a Cube reaction Hybrid HPA Race 500 29er - it comes with an 11 speed 42t cassette  and 15t front . Quite honestly it pulls pretty strongly in any gear - i probably only use half the cassette - in fact after a few months i realised that the factory had shortened the chain by too much so it wouldnt even go into the largest cog. If you buy one with a bosch motor the performance cx is the motor to go for. I'd also recommend freeborn cycles - i got a good deal out of them.


 
Posted : 05/11/2018 9:05 pm
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Thanks all - knowing that the bosch motor spins the chainring faster than the pedals explains a lot..

So, now looking at this

https://www.bike-discount.de/en/buy/radon-zr-lady-hybrid-7.0-500wh-714314

Bosch Cx motor, 500Wh battery, 1x11 and a decent fork. Battery integration isn't as nice as the Cubes, and no space for a bottle, but looks good apart from that I think. Bit pink though.

Any thoughts?


 
Posted : 06/11/2018 3:48 pm
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1:1 is about right, you go faster up. and it's low enough not to kill the motor. for extremely steep stuff, you could potentially go a wee bit lower.


 
Posted : 06/11/2018 4:03 pm
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Looks ok

Note that warranty on ebikes appears to be via 'selling country only' - so it might have to be sent back if issues, but there are beginning to be bosch specialists in uk for servicing etc

Bosch motor (apparently) drags when switched off (and above 15mph)

All ebikes are Bloody heavy

You might get a uk sale bike for a similar price e.g.

https://www.freeborn.co.uk/cube-access-hybrid-pro-500-2018-white-blue-electric-women-s-mountain-bike-27042?gclid=EAIaIQobChMIkICe8ZPA3gIVzLHtCh0MUgd8EAQYASABEgLyKPD_BwE


 
Posted : 06/11/2018 4:06 pm
 geex
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Radon looks a good buy for the money. Not sure the colour goes with my eyeshadow or nails though.

Cube a little less so (VFM not to compliment my make up)

buying from an actual shop in the UK is definitely a good idea though. Motors aren't massively durable or reliable. There's a guy in the UK now servicing and replacing all bearings (out sourced and manufactured for him) on Bosch motors.
Seems a sound bloke too.
http://www.performancelinebearings.com/


 
Posted : 06/11/2018 4:35 pm

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