MatthewBaynham

I need to replace a crankset. The groupset on the bike is a mixture of different Shimano, but everything is old. I'm guessing about 25 years old.

The old crankset says "e300x" on the side of it.

If I buy a brand new crankset Shimano FC-345 Compact Crankset is that going to be compatible with the same bottom bracket as well as compatible with the same crankset removal tool?

dedhed

No.
Your old crank uses a square taper interface and the proposed new one is octolink.
3 things to keep in mind with BB. Interface - how the crank mounts on the axle. Spindle length - How long does the axle need to be to clear the frame and give proper chainline. BB/.frame interface - Pressed in, threaded, what thread type, internal bearing external bearing.
That's just the beginning.

The crankset ALWAYS determines what the BB will be. It's not real often when changing crankets that the existing BB can be used.

https://bike.shimano.com/en-EU/produ...0/FC-R345.html

MatthewBaynham

Cool, thank you for that, it was very useful.

I'll go for a Shimano Claris FC-RS200 Crankset 2x8-speed then.

dedhed

Look at your existing crankset on the backside of the arms for an actual model number. Once you find that research what the correct spindle length is for thtat crank. Then see if the length is proper for the proposed new crank.

the Fc-rs200 shows a 110mm length recommended to produce a 43.5mm chainline.
https://bike.shimano.com/en-EU/produ.../FC-RS200.html

https://www.sheldonbrown.com/bbsize.html

dsbrantjr

Even though that is a square taper crankset you may still need a new bottom bracket if the spindle length is not correct for the FC-RS200.

Iride01 

You can probably change out the bottom bracket to match what ever crank you want to get. A new bb can be as little a five bucks, depending on what is required for the cranks you get. However you'll have to know more about the bb shell on your frame. Since it sounds like your bb is a cartridge type, you might have a wealth of information written on the side of it if you think you are able to remove it to look at.


As for whoever said the existing is square tapered, then can you expound on that. I see a lot of octolink bb's with "es300" in their description. Though not the "e300x" as the OP mentions. So what's that reference?

MatthewBaynham

So with the old one spindle length is 115mm. (Shimano FC-A300)

And the new one has a spindle length of 110mm.

Is there going to be major problems?

I am assuming this means my feet will just be 5mm closer together and the chainrings will be 2.5mm closer to frame.

Is it still going to work?

curbtender

That would push your chain line too far out. I think you would appreciate a new BB on a 25 year old drivetrain.

Bill Kapaun

So, you've already changed the crank from an "e300x" The BB for the double version of that is listed at 113mm.
You need to look closer at the last link in post 4.
Also look at the various spindle lengths. They are frequently NOT symmetrical.

dedhed

VeloBase.com - Component: Shimano FC-A300, 300EX

dedhed

https://www.jensonusa.com/Shimano-UN55-Bottom-Bracket

https://www.jensonusa.com/Shimano-UN-26-Bottom-Bracket

dedhed

Unless you own the tools, or don't mind buying tools you may only use once, I'd suggest having a shop replace the BB.

The issue is your existing BB for the EX 300 crank is likely a cup & cone BB. This will require a crank arm remover, a tool for the adjustable cup lock ring, possibly a tool for the adjustable cup, and yet another tool for the fixed cup. The fixed cup will also usually put up a fight, sometimes a considerable fight, coming out.

The new BB will be a cartridge type which will require yet a different tool for installation.
All told the parts will be less than the tools to do the work.

Iride01 

This is so true. I have a few bicycle tools I only used once and likely will never use again. If I'd taken two of my frames to a local bike shop when I changed BB's and cranksets, I probably wouldn't have spent any more than the tools cost.

With their guidance, you wouldn't be sweating or questioning what you have and need.