So what will a larger Chainring deliver to your eMTB...

[PhilBaker]

Having put larger chainrings onto non electric bikes, clearly it can improve your top speed before your legs run out of steam ? (at the cost of harder climbing in the lower gears) but interested to hear about peoples experience on eMTB's.

• Is there any impact/things to consider with regards to the motor?
• Does the drivetrain wear improve?
• Given the speed limiter, is the real advantage only felt when derestricting your bike in order to reach faster speeds?

I have a 36T as standard and loads of room, so could easily increase the size if the merits are there. Some eMTB's seem to have a super small chainring vs acoustic bikes, soI assume the electric element does come into chainring sizing.

Many thanks for your words of wisdom and experience!

 

[Gary]

• Is there any impact/things to consider with regards to the motor?

No. not really

• Does the drivetrain wear improve?
• Given the speed limiter, is the real advantage only felt when derestricting your bike in order to reach faster speeds?

Unless your motor is derestricted or you like to pedal down a lot of highspeed gravity assisted descents with no motor assistance (or you are unable to spin relatively quick cadence) you'll not gain much by fitting larger than a 36t ring

Assuming you are using a standard HG cassette your highest gear just now of 36x11 reaches 15mph at a paltry pedalling cadence of just 55rpm, most experienced cyclists should be able to hold 90rpm fairly easily.

a larger chainring will mean you'll spend less time in the smaller sprockets therefore they should wear less quickly.

 

[PhilBaker]

Yeah, your spot on Gary, my highest gear is 36*11 and yes, at 15mph my legs have more left but the weight of the bike limits going much faster unless it's downhill.

I was reading the earlier post about someones chain & cassette being worn out after less than 200 miles and wondered if there was a recommended front chainring size to consider on an eMTB.

Is there much difference going from 36T to 38T?

 

[Gary]

Don't worry. Anyone wearing out a decent quality cassette in 200 miles isn't maintaining/cleaning their drivetrain regularly enough or shifting gears smoothly (probably both).

I ran a 38t ring on a derestricted E Hardtail with slick tyres to commute on for a while. It's not a great difference from a 36T but It did mean I used the 11 and 13t sprockets a little less and could pedal to at a slightly higher speed.
This shows you the difference in cadence required to attain the same speed (above restriction limit) between using a 36 or 38t chainring

As you can see a 38T wouldn't be of any real benefit unless your bike is derestricted

 

[Rosemount]

Ground clearance is a factor .
Climbing over logs or rocks the bigger the chain ring the more likely you will hit it ...

 

[Sander23]

I went from a 16t to a 20t and the difference is huge at higher speeds( bike Is deristricted though)

 

[Doug85]

Don't worry. Anyone wearing out a decent quality cassette in 200 miles isn't maintaining/cleaning their drivetrain regularly enough or shifting gears smoothly (probably both).

I ran a 38t ring on a derestricted E Hardtail with slick tyres to commute on for a while. It's not a great difference from a 36T but It did mean I used the 11 and 13t sprockets a little less and could pedal to at a slightly higher speed.
This shows you the difference in cadence required to attain the same speed (above restriction limit) between using a 36 or 38t chainring
View attachment 46522
As you can see a 38T wouldn't be of any real benefit unless your bike is derestricted

I have a bosch gen 4 smart system 36t on Cube action team 160 2024 but on the long straights im out of gears on a 1x12 at 15.5mph legs start spinning like mad.
The bike feels like hitting the breaks! So this is something i am going to look in to this week and see whats what. My bikes not messed about with all standard as of the motor! I wouldn't touch it, it's just that felling of hitting the breaks when you start spinning out it's tiring and slows you down alot. i can't get the bike to 18mph while peddling under my own power the bike's got no more omph in 12th on 36t chainring it won't go past 15.3mph in 12th gear on straight so motor is always going! never felt it cut off yet! Never been able to get the bike higher speed under my own steam! This is the total opposite of what i thought would happen before i got it being my first ebike i thought I'd always be beating the motor and peddling alot under my own steam, i could be more wrong! I think even a 42t would be a perfect match as do alot straights even going up steap hill in 1st on the 1x12 the bike's going so slow almost rolling back and legs are spinning like a car led lining in 1st thats with the bosch motor maxed out in custom settings in turbo!

 

[alancube]

I changed my Cube's 34 to 38 as I never seem to use the lowest gears so this helps but mainly changed it for the higher gears as I ride road to get to anywhere 'off road' and as the bike is deristricted I can really power along - love it!

 

[juggernaut]

I changed my Frey from a 40 to 48. Much better use of all the gears and less use of the 11T cog.

 

[Amber Valley Guy]

I have a bosch gen 4 smart system 36t on Cube action team 160 2024 but on the long straights im out of gears on a 1x12 at 15.5mph legs start spinning like mad.
The bike feels like hitting the breaks! So this is something i am going to look in to this week and see whats what. My bikes not messed about with all standard as of the motor! I wouldn't touch it, it's just that felling of hitting the breaks when you start spinning out it's tiring and slows you down alot. i can't get the bike to 18mph while peddling under my own power the bike's got no more omph in 12th on 36t chainring it won't go past 15.3mph in 12th gear on straight so motor is always going! never felt it cut off yet! Never been able to get the bike higher speed under my own steam! This is the total opposite of what i thought would happen before i got it being my first ebike i thought I'd always be beating the motor and peddling alot under my own steam, i could be more wrong! I think even a 42t would be a perfect match as do alot straights even going up steap hill in 1st on the 1x12 the bike's going so slow almost rolling back and legs are spinning like a car led lining in 1st thats with the bosch motor maxed out in custom settings in turbo!

Is that a 85nm motor? If it is you have a problem, a 34t chainring in the smallest rear cog should get you past the 15.5mph limit. Are you sure it's not your cadence that's the problem? Can you change your display to cadence and see if your hitting 70-80 rpm constantly (by constantly I mean easy going flats or gradients, and using the gears to keep the cadence above 70)?