Here's the deal: I have a Soma Smoothie Frame with a Square Taper Campy Crank. I want to change to a 36/46 chainring setup, but the Campy crank has a big 135mm BCD. I am looking to stay with 172.5mm crank arms and the 9 speed cassette on the back.

I ride mostly for commuting, but will be doing a 300 mile charity ride the end of July. Currently I don't have a decent hill climbing gear, and never use the big 53 tooth ring. I tried to find a square taper 36/46 9-Speed crank, but was unable find any.

Please recommend some crank and bottom bracket combos that would be a good fit. I am really confused by all of the different BB types and associated crank options.

Thank you!
Pete

On my cross bike I use a Shimano CX50 46/36 crank, that I got from Merlin Cycles for $76:

https://www.merlincycles.com/shimano...set-65083.html

It'll require a new bottom bracket as it's a Hollowtech II crankset. I use this one:

Shimano BBR60 Ultegra Bottom Bracket > Components > Drivetrain > Threaded | Jenson USA

If you want to stick with square taper, so you don't have to switch out the bottom bracket, then why not consider a compact crankset (50/34)? Probably easier to find than a square taper CX crankset, and if you get one with 110 BCD, then you could aways put CX rings on it.

Campy's square taper is ISO standard, which is different than the JIS standard of most other square taper axles/cranks, so it would not work (well).

See? That's what I mean... Square taper isn't always square taper (JIS vs ISO) and will the hollowtech II bottom bracket be a direct screw-in replacement for the existing Bottom Bracket? Then there are GXP, BB86, etc.... So many different options.

It's pretty overwhelming when trying to do a simple thing like buy a single crankset and BB. It also hasn't helped that local bike shops just keep dropping the ball and not following through when I ask them for a quote or options.

Thanks for the info. Hopefully there will be more to follow.

There is no guarantee that a new crankset will fit the old BB; it might require a different length, then there is ISO vs JIS taper to consider.

Better to choose a crankset and see what its BB requirements are. Trying to finds a crankset which suits the BB is letting the tail wag the dog.

That is exactly what I'm trying to do. My problem is there are so many crank options out there and so many different BB types that I don't know what I need.

I'd love to have someone say: Here are 2 options that will both work well and fit your bike, one expensive and one inexpensive, and here is the difference between the two.

That is pretty much exactly what I've told 3 local shops near me. I said, "I want to buy parts and service from you. Give me an option or two under $150-175 and lets get this done" - none of them have called me back. It's rather frustrating.

Ask this same question in the C&V thread and you'll get multiple options and offers of cranks to purchase, some likely with a matching correct BB. That's because most of the modern world has moved away from square taper (please don't ask why, you'll get a lot of different opinions and some anger) and toward newer, different BB interface designs, some of which actually are easier to install and adjust.

Assume at any rate, square taper or no, that you will have to replace your BB. Not a big deal, but assume that.

For example, a good replacement would be a Shimano RS500 or RS500 crank. 110bcd, so it can take a 50/34 or 50/36 or even a 46/34 if you want. It's (gasp) Hollowtech, which means you'll need a different tool to install it than the one that you used to take off your Campy BB (my advice - buy both). Comes in silver or black. Awesome crank, have used several, cost around $90-100 new, less used.

Or, if you want something square taper and kind of vintage-ish, look for a late 80's Shimano or Sugino 110bcd crank and buy the correct size rings if the one on the crank aren't the size you want. Vintage guys often use older Deore or Sugino or SR 110/74 bcd triples as compacts with only the two outer rings installed. Can cost anywhere from $50-100 but expect to do some cleaning up and polishing.

Velo Orange, Sugino (try Rivendell) TA and other companies sell new compact cranks in square taper, cost start around $100 and go up, sometimes way up.

So, there are some suggestions. Paired with a wide range set of rear cogs, with a 50/34 compact you can climb pretty much anything.

It's not that hard. Break the problem down. Find an available crank with the rings you want. That CX50 option sounded pretty good - at least a good example. Then find a BB to fit. This is going to be Hollowtech II for this example. Then order the version that's compatible with your frame which is almost surely BSA aka British or English. Soma can tell you, for sure.

But that'll be the drill. Since you probably need the single most common bottom bracket standard out there, it's really just a question of picking a crank and then a matching bottom bracket.