| The standard gearing on the 748 is 14t on the front.
You can get 13t, but they are rarer than hens teeth.
The other problem is that the radius starts getting pretty close to being too much for the chain and can stress it if the chain isn't 100%.
I ran one for a while. Good fun for a time but I got cheesed off with the revs all the time.
The best way to do the gearing is with the rear but this is more expensive.
a 13t front is equivalent to having a 41t rear.
If you'd like to try it, I have the 13t lying around somewhere. You could try that for a while and if you like it, think about going the route of changing the rear?
Mail me if it's of use to you. | 
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