fullergarrett

While riding today, everything "locked up" while ascending a hill. I pulled over onto a sidewalk and reset the chain on the chainring (it has a tendency to fall off) and noticed a section of my chainring (4-5 teeth) was completely bent. I was able to limp home but the chain kept wanting to slide off and the bike wasn't shifting right. The other two larger chainrings are perfectly fine.

How difficult is it to replace a chainring? Would I be able to just replace the damaged chainring, or would I need to replace them all? What parts and tools would I need?

Any help would be appreciated. Here are some pictures of the damaged chainring.

CliffordK

Buy a new crankset. For the cheaper ones they are likely about the same price of a new chain ring.

It looks to me like the whole thing is riveted together. You might be able to get it apart, but there is no guarantee that you could find replacement parts.

The other option. I'm having troubles determining the material from the photo. If it is steel, you might be able to build an anvil to knock it back into alignment. Perhaps a thin piece of spring steel, or something like the back spine of a heavy chopper knife blade (throwaway thrift store special) that you could slip between the rings and use as an anvil to pound it back into shape (after first removing the crank).

fullergarrett

How hard would it be to replace the whole crankset? What tools would I need?

CliffordK

We'd need some more photos to verify, but it is most likely that you have a square taper ISA crankset.

Are there caps on the cranks? Do they pry out with a screwdriver, or thread out?

So, to get the crank off you'll probably need a 14mm socket (plus wrench) that is thin enough wall to fit in and remove and reinstall the retention bolt.

Then a crank tool. They come in a couple of varieties, some with a handle, some without.

They're usually pretty cheap.

Several different varieties. This one appears to come with the socket, and just needs a single wrench (which may be included).

Even if you choose to try to bend the ring back, you'll be much better off to first remove the crank.

tomtomtom123

https://www.parktool.com/blog/repair...on-three-piece

You need an 8mm hex allen key to remove the M8 crank bolts first. Then use a crank puller tool, with an adjustable wrench.

Also, your chain looks really dirty or rusty. You might want to clean and lubricate it more often.

fullergarrett

Here's a front and back-end view of the crankset. The bike is a 21-speed (7 gears on the rear, 3 up front.) I'll look later tonight and see if I can find a decent, affordable replacement crankset from my vendor (Modern Bike.)




Edit: Would a crankset like this one work on my bike? It appears to be somewhat similar to the one already on my bike. Or would I need this one?

CliffordK

Ok, so the allen wrench instead of the 14mm socket. The rest can come apart easily with the tool above.

In some cases if you have these silver rings on the bolts you can simply "remove" the chainring bolt and it will pull the crank off.

"Self Extractors"



However, I don't believe you have them. You could use them instead of the crank tool if you wish.

fullergarrett

So an allen wrench and the crank tool (like this one?) would be needed to remove the crankset. Would I also need to remove the chain completely before working on it, or should I be fine leaving it alone? If I need to remove it, I may just go ahead and replace it altogether.

Would this crankset work fine? According to the specs on my bike, it was equipped with a SR Suntour XCC, 28/38/48. It seems to be the closest replacement I could find.

CliffordK

Your first link is just a socket and Allen Wrench. So, not quite, or only half the answer.

Further down the page you see the Park crank puller.
https://www.modernbike.com/park-ccp-...e-taper-cranks



Or without the handle (out of stock).
https://www.modernbike.com/park-cwp-...l-crank-puller



Is that crankset out of stock? If available, it would probably be fine.

Count the teeth on your largest and smallest chainrings. Does it list a crank arm length on your old crank? Is it comfortable?

Keep in mind you may need to do some derailleur adjustments when you put on a different brand of crankset.

dsbrantjr

With the chainring bent that severely I would not be at all surprised that the chain has some damaged links. It might be wise to replace it as well.

CliffordK

Often recommended to replace the chain when a sprocket is replaced (usually rear, but would also apply to the front).

Perhaps a photo of the rear cassette or freewheel with the rear wheel off, and chain off the wheel.

Chain Tool? Freewheel or Cassette tool?

fullergarrett

Back in May I converted the bike from a freewheel to free hub, so the rear cassette is new. I didn't change the chain. I have the cassette tool and I believe I have a chain tool somewhere around here.