Bike Forums - EBike Chainring Selection Help

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EBike Chainring Selection Help

I own a 2022 Giant Fast Road EBike. I'd like to swap out the 'stock' chainring (42T) for a chainring with more teeth (say 52T or more). I'd prefer 1) SRAM or Shimano, a product tolerant of heavy/ all-weather commuting on rough roads, and 3) something doesn't require me to buy new crankarms. What model do you recommend?

Do your homework well. With non E bikes this is usually fairly straightforward. Chain ring bolt circle diameter, number of bolts being first to match. But some E bikes use crank based sensors to control the E assist and I don't know if that will change with a ring that's nearly 25% larger.

I assume you're after a slower cadence for the same speed. Andy

1. Remove the crank so you can access the chainring bolt behind the crank.
2. Remove the chain guard so you can see how the ring interfaces with the crank spider.
3. Measure the bolt center diameter (BCD). That will be the centerline distance between two opposite bolts.
4. Go online and search for 1x chainrings having the 4-bolt pattern, BCD, and tooth count that you desire.
5. You might need a longer chain.
6. Put it all back together.

Or, learn to pedal faster. Seriously, reputable vendors of e-bikes choose their gearing carefully for the job at hand, and it's better for your legs.

Quote:

Originally Posted by Andrew R Stewart (Post 22645195)

Yes, I'm not able to put much power / torque onto the pedals on flat roads using maximum electric assist. Hopefully a bigger chainring and possibly a smaller cassette may help. (I have an 11-34 cassette so not sure I can go much smaller.)

I would check with Giant and see if they have a max chainring or check with the motor manufacturer (Yamaha more than likely) and confirm with them aside from spacing issues what is the max chaining you could run on their system. Then go back to Giant and see what the max size you can fit on the bike and what the Bolt Circle Diameter is.

You could also consider using less assist instead of grinding in a tiny cog at the back in full power all the time consider using all of your gears and less power. A lot of people like to use their assist as the gearing and their gears as extra dead weight and that can really burn up the system and waste a lot of money replacing barely worn cassettes with single damaged cogs due to people not understanding the bike is a bike that also happens to be able to assist you but is a bike first and foremost.

If I am on a flat road or downhill I am not going to be in my highest setting generally because the motor is just going to give more power than I need and I will just spin real fast and not put much down.