What size BMX cranks do I need? When it comes to shopping for a new set of BMX cranks, it can be a little tricky deciding just what is right for you. Not only do BMX cranks come in multiple lengths, but they also come in three different spindle sizes; 19mm, 22mm and 24mm. Over the years, BMX has evolved and products have been refined over and over again to get to where they are these days. The quality has hit a level that has made it easy to trust that you’re going to be able to put your bike through some heavy riding and it’s going to withstand the abuse. At least this is true if you’re going with a reputable brand and not going with the cheapest option available. Now, there’s probably a lot of newer riders out there that are looking to upgrade their cranks on their bike. The question of “what size BMX cranks do I need?” has probably crossed your mind many times just looking at the options. So, we’ve put together a BMX crank size guide to help you figure out just what is right for you.
Crank Arm Length
Crank arm length is more of a preference. Most riders these days run a 170mm or 175mm size, but you could go shorter or longer (Shorter is more ideal for street and flatland riding and longer is more ideal for jumping and racing). That 170mm – 175mm size is pretty ideal for street, park and dirt riding. The length is one of those things that come down to rider preference. We’ve seen a lot of riders swear by shorter cranks saying that it makes some tricks easier and give them foot clearance for their pegs. Then there are other riders that prefer theirs a little longer for more power when cranking or balance. Most cranks come in that 170mm to 175mm size since those are the most common sizes, but Profile Racing for example offer a TON of sizes for every rider out there as you can see above.
Spindle Size
BMX cranks come in three sizes; 19mm, 22mm and 24mm. The size is more about the type of rider you are and the amount of abuse you put on your cranks.
19mm – If you primarily ride ramps or trails and you are a smoother rider, not doing any big drops to flat or rough landings on a regular basis, the 19mm spindle size will be a great option. These cranks will hold up to street as well, especially if you are a smoother rider that isn’t dropping off roofs or something crazy. The 19mm option is going to, in most cases, save you some weight as well.
22mm – The larger spindle diameter gives cranks extra strength and make them harder to bend. These are more ideal for the all around rider that likes riding street, park and dirt. They can hold up to drops, grinding and pretty much what most riders are doing on their bikes. The 22mm size has become a lot more common over the years because of the strength benefits, which isn’t a surprise with how wild riding is these days.
Flybikes Dolmen II 24mm Cranks
24mm – The 24mm spindle size has become more popular over the past few years after Fit introduced the first set on their Indent cranks, mostly because these were designed for the street guys who are heavy on their cranks and tend to do a lot of heavy drops and really put a lot of abuse on their bikes. The larger spindle diameter makes it harder to bend, and some, like the Flybikes Dolmen II cranks even come with extra gussets (extra metal plating for strength) to resist bending and damage. The 24mm size cranks are heavy duty, so they will likely withstand what most riders are doing on their bikes. Obviously as the spindle sizes go up in size, weight can go up a bit due to extra material.
Bottom Bracket Size
This is pretty much the most straight forward part to the whole process of deciding what size cranks to get. The Bottom Bracket is the part of the frame where the cranks bearing press in that allow the spindle and crank arms to spin. Since the vast majority of BMX frames come with a Mid style bottom bracket (This is the standard size for all BMX frames these days), you can run 19, 22 or 24mm cranks as long as you change out the bottom bracket bearings to match the spindle size. So, for example right now your bike has 19mm cranks, that means you have a 19mm Mid bottom bracket. If you decided to go with another set of 19mm cranks, you do not necessarily have to change out the bottom bracket bearings and could slide the new cranks on. However, if you decided to go up to a 22mm or 24mm set of cranks, you would need a new bottom bracket to match the spindle size.
So, to sum this all up! What size BMX cranks do I need? Well, it’s a mix of rider preference and the type of riding you are doing. If you’re strictly just a street rider and you’re doing a lot of big grinds, drops and more, then we would recommend a 24mm crank with shorter arms in the 165mm to 170mm range. If you’re a more of a ramp and trails rider, then go with a 19mm set with slightly longer arms in that 175 – 180mm range. If you’re looking to ride a little bit of everything and you are going to send it on some bigger stuff, go with that 22mm size in a 170mm – 175mm size.
This is more of a suggested guide, but works for most BMX riders out there. What do you think? Let us know in the comments!
Also, let us know what cranks you run, the sizes and why! Maybe getting a bunch of feedback from different riders will help out somebody that is on the hunt for the right BMX cranks for themselves!
Note: This post contains affiliate links to Source BMX and we could receive a small commission that supports the site if you were to buy a set of cranks from them. We would never recommend a brand or product if we didn’t think it was quality.
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