chainged chainring from 44T to 58T on 7-speed ebike. What adjustment is needed?

[clksoft]

I have an izip via urbano 7-speed electric-assist ebike.
I replaced the 44T chainring and its outer chainguard with a 58T chainring and a correspondingly large chainguard.
I guess I'll probably at least need a longer chain and also some derailleur adjustments.
Yet, the first and immediate problem I notice is that the chain has a tendency to jump off the chainring towards the outside of the bike and gets stuck between the newly installed chainring and chainguard. How can I fix this? I don't have a front derailleur, so whatever derailleur adjustment I could do has to be in the rear. Or is the chain jumping off to the outside just a symptom of it being too short now what I have a wider diameter chainring?
I'm a clueless newbie and would appreciate any advice or suggestion.
Thank you.

 

[alfeng]

Possibly & probably it is the now-too-short chain which is casing the problem.

 

[swampy1970]

Take that dinner plate chainring off and put a 52 on. You'll still most likely need a longer chain but unless you're planning on cruising at 35 mph you don't need a 58. Leave that to Tony Martin.

 

[clksoft]

As a matter of fact. It was indeed due to the chain length.
I went to REI and the bike mechanic put on a new chain and fined tuned the derailleur settings.
No more problem with the chain jumping off.
However, I realize that even with the eletric pedal assist, it still requires stamina to go over 20mph on a flat surface.
So, if I were to do it again, I might indeed go for 52T given that I've already changed the rear cassette to have a 11T small cog (original small cog was 14T). But it cost me about $80 to import the 58T chainring & guard from Taiwan. So, I'm sticking with them.