Changing the synapse to a triple probably requires new shifters, new crankset, new front derailleur, and possibly a new rear derailleur.

It can be done, but it'd be an expensive switch.

If you want to tell us exactly what's on either bike - when you go home tonight, you can either count the number of teeth on each bike up front or in the back (really, you just want to know how many teeth the biggest cog in the back has, and how many teeth the smallest chain ring in the front has. ) Probably what I guessed they were in my post up there is right or pretty close to it - and if that's the case, there's no way in heck that's a 2% difference in gearing. And even if you changed the rear cassette in the back to an 11-32 or an 11-34, you'd probably still be missing gears - but that may be enough to make it ridable for you.