170mm Vs. 175mm

Shorter crank arm = faster spinning
Longer crank arm = more leverage

Not sure about the physics of it all, but that's at least one angle to take. Road clearance might come into it as well, depending on how big you (and your bike) are.

wardie2000 said:

Hi,

Could someone tell me the advantages and disadvantages of using chainsets of the lengths above.

Can 5mm really make that much difference?

Thanks

I normally ride 175s, but I like the 170s on my crit bike. Spins up faster and (at least in my mind) I get better cornering clearance for tight turns. Also, I believe the proper vernacular is "cranksets" not "chainsets".

capwater said:

Also, I believe the proper vernacular is "cranksets" not "chainsets".

I think that depends on whether it was installed with a wrench or a spanner.😉

You'll find a lot of conflicting opinions on how crank length should relate to leg length, but it's pretty personal. I use shorter cranks mostly because they're easier on my knees.

If you buy a chainset, it comes with chainrings, if you buy a crankset, it doesn't come with rings. I've got 175's on one bike and 170's on another. I can't say I've ever noticed much difference. Maybe if you're a TDF rider or something you might notice. Boudreaux? Any comments you'd like to add?

Bill.

shannons dad said:

If you buy a chainset, it comes with chainrings, if you buy a crankset, it doesn't come with rings.

Maybe in the UK, but not in the US. Guess this is like with cars, slightly different terminology. Took me forever to understand WTF a "bonnet" was.

capwater said:

Maybe in the UK, but not in the US. Guess this is like with cars, slightly different terminology. Took me forever to understand WTF a "bonnet" was.

You have a point there. Except wardie2000 is a UK member.:p

Bill.

wardie2000 said:

Could someone tell me the advantages and disadvantages of using chainsets of the lengths above.
Can 5mm really make that much difference?

5mm does make a difference.

Crank length is somewhat determined by (apart from leg length, obviously) the type of riding you'll be doing, and the type of rider you are. Fast twitch, sprinter types, who are most likely gunna win a race from a very fast finish, tend to prefer a slightly shorter crank for their height, the opposite is becoming typical for slow twitch, "grinder", aerobic types, who would probably be better off with a slightly longer crank.

531Aussie said:

5mm does make a difference.

Crank length is somewhat determined by (apart from leg length, obviously) the type of riding you'll be doing, and the type of rider you are. Fast twitch, sprinter types, who are most likely gunna win a race from a very fast finish, tend to prefer a slightly shorter crank for their height, the opposite is becoming typical for slow twitch, "grinder", aerobic types, who would probably be better off with a slightly longer crank.

For the vast majority of us, the differences in crank length are more useful in getting the best fit for the bike, not to go faster or climb mountains better.

To add to the confusion, I find my knee prefers a shorter crank. 172.5 on my mtn. bike (for now), and a 170 on my road bike. I rode for years with a 175 but since my knee blew up, it's been much happier with less range of motion.

I have a 30" inseam by the way.