Switching from 175 mm to 172.5mm cranks

[rockyraccoon]

My bike has a chainset 52 x 39T and the cassete is 12-25t. Thinking about replace it for a compact (34/50) chainset with a 172.5mm crank length.

My rides consist of hilly routes... I don't do more than 22mph on flat..

So any advantages? Will I notice the difference for the type of ride I do?

 

[oldgreyandslow]

you won't notice the crank length but you sure will notice the 34 front on hills, much easier

 

[rockyraccoon]

wouldn't it be cheaper just replace the smaller chainring insteand of the hole set?

 

[gaz]

Some say that it is easier to spin a smaller crank.
Downside is you have less leverage with a shorter crank arm. You shouldn't have a problem if you are using a geared bike but you might notice that you are running different gears for different speeds.

 

[Globalti]

The slight change in crank length is insignificant because the gearing will be different anyway. For a leisure rider a compact is ideal, it gives a much more usable range of gears than a traditional big crankset. Also if you change from a traditional BB with square taper axle to a more modern Hollowtech type BB you'll notice a big difference in the stiffness. Definitely a very good upgrade.

If your rides are hilly consider also fitting an 11 or 12 - 27 cassette, which will give you much easier climbing.

 

[Crackle]

wouldn't it be cheaper just replace the smaller chainring insteand of the hole set?

Replacing the chainrings would probably be cheaper and a larger spaced rear cassette as Globalti mentions.

 

[rockyraccoon]

Replacing the chainrings would probably be cheaper and a larger spaced rear cassette as Globalti mentions.

Thanks.. I will probably do that..

Is it possible to remove each cassette individually to replace only, for example, the 25t? Or would I have to replace the the entire set? I've never removed it so wondering if it is simple as that!

 

[numbnuts]

have a look here for taking the cassette off
http://www.parktool.com/blog/repair-help

 

[the_mikey]

Don't forget the rear derailleur may not necessarily have a cage long enough for the bigger cassette, also this may also create the need for a longer chain (or a new chain not shortened as much as the previous chain.

 

[HLaB]

I couldn't say 100% but when I changed from 175mm cranks to 172.5 I spin more and hopefully it is better for my knees but it was on two separate bikes and therefore not very scientific and results are subjective. I think the more influential change was different chainrings which has similar effects to changing the cassette.

 

[evilclive]

I couldn't say 100% but when I changed from 175mm cranks to 172.5 I spin more and hopefully it is better for my knees but it was on two separate bikes and therefore not very scientific and results are subjective.

And for an opposite story, I noticed after a couple of years I had 175mm on one side and 170mm on another.

The three bikes I ride most have 180, 175 and 170mm cranks, and TBH I can't really tell much difference.

 

[HLaB]

And for an opposite story, I noticed after a couple of years I had 175mm on one side and 170mm on another.

The three bikes I ride most have 180, 175 and 170mm cranks, and TBH I can't really tell much difference.

Yip, its all subjective ;-)

 

[JonnyBlade]

I went from a 52/42 working a 12-25 9 speed to a 53/39 running an 11-32. I am soooooooooo very pleased with the difference. Not being a big fella I find it easier to spin than grind so it suits both on the flat and up hills