Cycloptishred

Hey guys, I think this is my first post here so thank you all for having me and taking the time to read my questions.

I recently bought a used Specialized Vita, the previous owner said he would give me the parts to fix this at a later date and isn't returning my messages (hah) so I came here to ask what kind of part I would need to fix this.

Here's an image https://i.imgur.com/LDvC53T.jpg the pedal swings in and out while I am riding. Any suggestions on a cheap way to fix or should I just go get a new part? And if so, what part would that be?

Thanks for looking

frankenmike 

New left crank arm, new crank bolt. Probably square taper, but hard to tell based on the picture.

Wilfred Laurier

A new bolt and anew crank arm should cost less than $20 at an lbs.

GravelMN

If you have a bike co-op in your area, chances are you can get a used crank arm and the appropriate bolt for a couple of bucks. This site will help you identify parts by their correct names and provide information on what will need to be done to fix many problems. Just roll over the diagram of the bike and point at the part desired for more information.

Park Tool Co. » ParkTool Blog

Unfortunately, whoever bodged that repair had no idea what he/she was doing and probably ended up damaging the crank arm beyond salvation. If you are lucky the bottom bracket (the bearings and shaft on which the crank arms turn) is undamaged. There are a few different types of bottom brackets and crank arms come in different lengths 170mm and 175mm probably being the most common. Just make sure you get a crank arm of the same length as the one you are replacing and that works with the same bottom bracket.

Retro Grouch 

Almost surely.

That's not the right bolt for holding the crankarm onto the bottom bracket. If the thread pitch for the bolt is wrong, the bottom bracket spindle may have also been cross threaded and ruined.

Loose left crankarms are a common bicycle repair problem. It's always the left one that gets wallowed out. When I had a bike shop I always kept a couple of left crankarms in stock. If you're not picky about finding an exact match a replacement crankarm will probably cost around $15.00 or $20.00. Two things to look for: 1. notice the orientation of the square hole relative to the arm. There's squares and there's diamonds. The difference will be obvious if you compare the new arm with your old one. 2. Crankarms come in different lengths. The length will be stamped on the inside edge near the pedal hole. It's better if they match but honestly, if they're off by a couple millimeters, you probably won't notice when you ride.

Take your whole bike to the shop to buy the crankarm. While you're there, also buy a new crank fixing bolt. Before doing anything else, try screwing it into the bottom bracket spindle with your fingers. If it doesn't go in smoothly, your bottom bracket has been cross threaded and you've been screwed. A replacement bottom bracket will cost around $30.00 and will require special tools for removal and reinstallation.

Good luck.