Howdy, I have a crank with waaaay to many teeth at the crank. Ideally I’d like to replace it with something with less teeth as I live in an area with lots of hills…
The crank set says it’s. Lasco CR-40L. I assume that refers to the amount of teeth on the sprocket it came with.
Can anyone help me understand what I can replace it with?
Ps I have ordered a new cassette which will help a little.
by BarronVonCheese
3 Comments
Are you sure it’s 70mm? If it’s ~65mm between bolts that’s 110mm bcd, if it’s ~76mm then it’s 130 bcd
A more relevant measurement would be the distance between one of the bolts you selected and the center of the crankset. Multiply that measurement by two and you have your bolt circle diameter (bcd). Google “5-bolt ###bcd chainring” and you should find an assortment of chainrings to choose from.
The sprocket is called a chainring. You need to figure out the right mounting size as you’ve identified, this is called the Bolt Circle Diameter, or BCD.
You can measure between the bolts as you’ve done but you’ll need to be more precise than 7cm. Going off common sizes if it’s 64.7 mm then you’ve got a 110mm BCD which I feel is most likely. If it’s 76.4mm then you have a 130mm BCD.
Look for a 5 arm chainring with the correct BCD and the number of teeth you want. I’m not sure what the smallest ring you could fit is but you’ll be able to go down to 34 tooth at least.
Some chainrings have a narrow/wide tooth profile to help stop the chain from falling off but if you don’t have this now then you likely won’t need it.