Relative to other industries (e.g. computers) on-line, assembled bike sales make up a relatively small proportion of bike sales. Most, if not all, major computer manufacturers have direct on-line sales. That doesn't appear to have happened in the bike business.

a) crazy to assume that a bike comes out of the box fully-adjusted from the factory. It's pieced together (mostly), but rarely do they shift correctly out-of-the-box. If you don't know what you're doing, you need to have a qualified shop do it otherwise you could literally get killed.

b) I did this out of stupidity last season--switched to my beater wheels and never spun the cranks to "set" the chain into a cog. Pedaled a rotation and tore the derailleur into the rear wheel. Swore quite a bit.

c) Online sales are fine and dandy as long as you know how to properly assemble/tune a bike.

d) OP screwed up, no ifs ands or buts. Sorry, that's the way the derailleur crumbles.

THANKS! Lots of good answers here, I appreciate the errors of my ways..
Now feel free to compliment my choice of ditching the Hutchinson Equinox sh*t tires and going to Fiammantes, and white bar tape + San Marco instead of the Celeste tape / cheap black seat that came in the box....
(to get the attention away from my mechanical defiencies.....:rolleyes: )

BTW, for my defence: My first road bike for years bought last year : a Pista. ... . .do the maths (or lack of gears - equation)

There's no shame involved with the mistake you made completing the build. Not everyone is their own mechanic. I'm sure the next time you build a bike, you won't allow the same mistake to be made.

It doesn't sound like the wheel or frame was ruined, so getting it fixed should cost too much.

OP,
I am glad you found your bike, as I remember you juggling options last year. Sorry you got burned.

And it can happen. I have bought complete bikes for my son from Nashbar, and went through every adjustment and fastener. But when I bought a BMC SL02 from Competitive Cyclist, I barely looked at the shifting and was off and riding. I was foolish to trust it blindly, and got very lucky.

Don't beat yourself up too badly. You aren't hurt and money, at least in the US, does grtow on bushes.

truth is, aside from bad luck of getting a bike with the inboard rear derailleur stop too loose and rear derailleur cable tension too high to shift the derailleur into the spokes, the OP dodged a big bullet. As mentioned, this could have easily trashed the frame and the rear wheel.

OP...these are your steps:
1. Remove chain and what's left of the rear derailleur
2. Park dereailleur hanger tool to straighten hanger.
3. Install new rear derailleur and adjust it properly before installing the chain.
4. Install new chain and adjust length.

Should get you back on the road. If you don't have a real big cassette in the back, a Campy short cage rear derailleur is what you want. If you anticipate putting a large cassette on in the future, just get the mid cage Campy rear derailleur...btw...what I ride which shifts as well as a short cage....or close enough.
PS: I have an extra, nice short cage Centaur 10s rear derailleur if interested I will sell you for a fair price. PM me if interested..below:

More good advice, thanks.
Was so p***ed off I haven't touched the bike since hanging it up. Will disassemble and clean up the frame.
As for the short - long cage Campy I'm not sure! It's a 2014 Impulso with a full Veloce groupset and a 10speed rear.
How old is the Centaur, is it new or used? :-)

From his pics in the OP, picture No. 2 shows that the hanger is trashed, broken off at the threaded loop by the der when things went south. He needs a new hanger for that model Bianchi, too. Just a heads up.

Bill

Looks like a compact double crank and 12-25 -ish cassette and short cage on the bike. Can't be sure.

OP, you can count the teeth on the largest cog of the cassette to be sure. That helps determine what you need for rear derailleur.

Good catch on the broken hanger....I should have looked a bit closer.
Looks like a 25t largest cog OP...which shifts fine with short cage rear derailleur.
Will tell you OP...a dork disk gets a lot sniping on the 41 and always the first thing I take off a new bike.
But...that said, that plastic disk saved your rear wheel which would have been gone with what happened....noting the telltale scuffs on the disk.

OP...Centaur rear derailleur is used...less than 500 miles. Nice shape. Its on deck to put on ebay at some point.

True, it is the hanger that broke, snapped off each side of where the bolt goes through.
Well, yes the plastic disk actually broke completely and was hanging off. Much rather get flak for the disk than having to replace a wheel, It's not like it gives me a massive weight penalty on the rear wheel........;)
PM me with a price for the Centaur!

PM sent

What's wrong with the Hutchinson Equinox tires. I got a bunch for $10 each a while ago and they work perfectly fine for winter riding.

Do not read any responses to your question and never ask it again.

You are experiencing the Wile E. Coyote phenomena where you don't fall until you look down and see you have walked off the cliff.

Are you referring to a rear wheel spoke protector?

:roflmao2::roflmao2: