well, sounds about like normal parent/offspring problem... as someone has said, your mom probably thinks she has your best interests in mind. try and figure out what these really are --- i.e. is she afraid of the dangers of cycling? does she just not like the idea of a 'kid' with such an expensive item? do she not approve of borrowing money b/c maybe she knows the dangers of debt and wants you to not develop any bad habits? anyway, if you can figure this out then maybe you can convince her...

on the other hand, sounds like your real desire is to ride! if so, then rather than sit around and complain about not having enough money for the bike you want, buy the best one that you can afford now. or do you already have a decent bike now? if you work at a bike shop you should know a good deal when you see one and be able to fix it up. then when you do later have more money, you should be able to sell whatever used bike you buy now for almost as much - used bikes don't loose value too fast unless you trash them. i bought my first road race bike at 18 used for $180 (ok, add 12 years of inflation and convert to Canadian, that's maybe $500cdn)... then you can ride and train now AND hopefully demonstrate to your mon that 1) you're serious about biking 2) it's not so dangerous since you're doing it anyway w/o the loan and 3) she'll see that it's something you're really working towards... i.e you're responsible and dedicated

plus, in the mean time you'll get to ride and train and then when you do really get that bike you want you'll really be able to use it. while a good bike is nice and you need at least something roadworthy, training and physical ability make for much more than the bike:: in college i was poor and my bike was junk and squeaked and sounded horrible, but i trained ALL THE TIME and at races guys would laugh at me and my ugly bike up until i dropped them! then they looked pretty dumb being dropped by the guy on the piece of junk!

just on a related note: between 16 and 19 i wanted a motorbike but my mom disallowed it b/c "motorbikes are too dangerous" (i ALREADY had the money from working). so since my parents were still giving me some money for college i accepted it and at 18 i bought my first road bike (described above) and starting racing which really started my love of bicycling. i had ridden as a kid and then a lot from 14-16 until i got a car when i quit b/c cycling wasn't 'cool'. later my bike got stolen and i bought a motorcycle at age 20 and just told my mom about it (i was in college and didn't live at home). it then took me a few years to figure out that i really like bicycles more than motorcycles... but maybe my mom's restriction helped me... who knows?