Has anyone increased their front sprocket size? Any concerns or issues?

[ck1224]

Not sure which model you have but I'm guessing that all the 20" wheel models have the same 14-28 rear cassette, which would be a much easier modification to reduce your cadence at 28mph. A rough calculation from me suggests that you should hit 28mph at just below a cadence of 90 with 52T on the front and 12 on the rear, whereas you are looking at almost 100 cadence for 52x14. A lot cheaper than having an 80T chainring cast (which would actually need less than a lazy 70 cadence to hit 28mph with 14T on the rear).

I calculated 110 cadence with 23" inch wheels, 72 with new chain ring.

 

[ck1224]

The chainring linked to by Timpo would also require you to replace the crankset as well, because those rings are meant for bikes with replaceable rings, which is not what your bke has. Also as mentioned, there is a good possibility an 80T ring would not even fit onto the bike; it may not clear the chainstays.

Ok, I can't tell what type of chain ring is on there. I thought it was possibly a type A (chain ring), but the bolt is really tight, so I didn't want to try to take it off unless I had to and see what it is. Rattan's tech. support doesn't know or won't help me with what kind of chain ring specifications are on the bike. However, it is a Prowheel (Prowheel stamp is on the crank arm, and I emailed them to find out more info about their products).

So,, you are saying that my bike doesn't use a type A chain ring, so ebikes use other types of chain ring types? I measured the chainstay to middle of crankset clearance and it would accommodate up to an 80T.

 

[Nova Haibike]

So,, you are saying that my bike doesn't use a type A chain ring, so ebikes use other types of chain ring types? I measured the chainstay to middle of crankset clearance and it would accommodate up to an 80T.

Your bike does not have a separate chainring at all; the ring is swaged (press fit) to the crank and is not removable. So if you want an 80T ring, you need a whole new crank that allows the use of removable rings.

 

[Papadevo]

The cheapest way to approach this is to change the rear freewheel to as small of a cog as you can fit, then up the chainrings/crankset if you can push harder at 70-90 cadence. I see some 7 speed free wheels available on Amazon that go to 11, but you will also need specialized tools to do the job yourself. Changing the crankset and chainrings could also involve a bottom bracket, FYI.
A decent bike shop will do this all for you for a small labor fee plus parts. They may be COVID busy, and annoyed by the last customer, but generally like folks that have some idea of what they want to do and are willing to pay for expertise. Reputable shops will get you an estimate before any work is done.
It’s possible to push 30+ mph with a 20” wheel and standard bike parts. Your bike will need some modifications. I have a no motor 20” folder and it is awesome in cites and navigating crowds by bike. May be best to enjoy what you have for what it is.
But have fun! One of the joys of cycling is experimentation so choose an option and go, go, go!

 

[ck1224]

I would recommend trying a new 11-28 or 11-32 rear cassette before changing the front ring or cranks.

You will also appreciate the increased gear range with the larger cassette and will not need a new chain.

yeah, I think that might be the best choice for now. I don't know if the rear cassette is standard or non-standard as some articles have mentioned that some ebikes have skinnier cassettes due to wider hub motors It is 1 1/4 inch spacing between the highest and lowest gears.

maybe that and bumping up to a 56 to 62T chain ring (not sure if I could find this, and what would be needed crankset and bottom bracket change).

 

[FlatSix911]

yeah, I think that might be the best choice for now.

I don't know if the rear cassette is standard or non-standard as some articles have mentioned that some ebikes have skinnier cassettes due to wider hub motors It is 1 1/4 inch spacing between the highest and lowest gears.

Good call.

The Shimano 7-speed cassette is a standard dimension and should be interchangeable... check with your local bike shop for a 11-28T freewheel.