Chainset help
 

Hi All, Hoping for your help.

I need to replace a double chainset with 4 bolts on a Specialized Sirrus gravel bike; model number CK-C614, square taper, 48/32 Tooth range, 110 BCD, 172.5 mm crankarm length.

I can't find a like for like replacement so I will need to compromise on some of the above ... but which ones and what will the implications be of any compromises?

The closest I can find are with sportandleisure.com, does any body have any experience of these?

All advice welcome.

Simon.

Apologies, just realised this is a USA website.

I am in the UK.

It's a world wide site. It's just mostly USA members.
Crank length is a personal preference.
110BCD is the Bolt Circle Diameter. Not important if you are replacing the entire crank. Important if just replacing the rings.

Your concerns are which Bottom Bracket type your frame uses and finding a crank that uses it.
Keep to similar tooth counts and you shouldn't have any FDER issues other than a possible minor adjustment.

You're welcome here and lots of knowledgeable people to help. Many of us buy from UK sites as well so we can help with that. I would recommend going to the SPA Cycles site or if near North Yorkshire they have their shop there. https://spacycles.co.uk/m8b0s109p0/Drivetrain/Chainsets They have a mindboggling set of chainsets to look at but you are basically looking for the SPA brand with the TD-2, XD-2 or RD-2 prefix, Double chainring models. These come in many crank lengths and usually choice of black or silver and choice of various chainring sizes and grades of durability and all are JIS square taper. The cost generally determines the higher quality (durability) of aluminum used for the chainrings and arms. The only thing is to check the length of the Bottom Bracket recommended listed near the bottom of the page under "Description". If your current BB is a different length you may have to buy a different one. I've used them a few times and always good to buy from. I'm sure if you contact them they would be very helpful with any questions.

If it's got a square taper BB currently, then I want to believe that it probably is a also a BSA threaded shell. So you really can just look for any crankset here or chainset there. That also comes with a BSA threaded BB. That can include 2 piece cranks that are a cinch to install. Or cranks that use octalink v2 or ISIS type BB cartridges.

Which any of those are easier to deal with than the old and unfortunately still with us square taper bb.

As mentioned, barring a really good and non-obvious reason to retain your current square-taper bottom bracket bearings, I'd suggest spending $20 on a new Shimano BBR-60 bearing assembly and then installing a Shimano GRX crank set, which is available in 48/31 with 172.5 arms.

There might be some concern over your derailleur's ability to shift a 17 tooth gap. In my experience, Shimano derailleurs that are spec'd for 16t, shift 17t just fine. Not sure about other brands. If you really require a 32t ring, at least one manufacturer sells one for GRX cranks, which could be swapped in.

Or you could install MegaExo bearings and an FSA crankset that is available in 48/32 with 172.5 arms, to save a few bucks by using lower-quality parts.

You "might" want different length arms.
Shorter people, older people and those with "bad knees" usually benefit from a shorter crank.
I put 165mm on my 2 conventional bikes. I can spin a lower gear faster and have more stamina, so I can spin longer.