Crank change

[gmw492]

Hi, I am looking at crank based power meters, I have 105 r7000 groupset on my bike 52/36 172.5, I have seen a 4iiii 105 r7000 power crank with various options in ratio and length.
Would I be able to do a straight swop and also would I be able to change it to 50/34 and 170 crank length, would I have to alter the chain or anything else, sorry if obvious to some but I have to ask I don't know,
thanks

 

[raleighnut]

Hi, I am looking at crank based power meters, I have 105 r7000 groupset on my bike 52/36 172.5, I have seen a 4iiii 105 r7000 power crank with various options in ratio and length.
Would I be able to do a straight swop and also would I be able to change it to 50/34 and 170 crank length, would I have to alter the chain or anything else, sorry if obvious to some but I have to ask I don't know,
thanks

Yep you'd have to shorten the chain and lower the front mech going from a 52 to a 50 big ring.

 

[Ming the Merciless]

For two teeth your chain would probably work fine as it is. It’s not so finely tuned that chains have to be an exact length to work just fine. Have you considered a left only crank and keep the chain set you already have?

 

[boydj]

You're proposing an expensive change. Unless you live in a hilly area or are struggling on the hills, then I'd question the need to change the whole chainset. There's always the option of a cassette with more hill-friendly cogs if there's only a few problem hills in your area and you need other options to consider.

 

[Ajax Bay]

looking at crank based power meters, I have 105 r7000 groupset on my bike 52/36 172.5, I have seen a 4iiii 105 r7000 power crank

I agree with @YukonBoy that the chain will be fine, with the proviso that, when it's currently in large and large, the RD cage points no higher than 5 o'clock. To quantify what @raleighnut said, the FD will need dropping about 4mm for the 50t ring.

You're proposing an expensive change.

Umm, yes! The OP wants a crank based power meter.

 

[boydj]

[QUOTE................
Umm, yes! The OP wants a crank based power meter.
[/QUOTE]

But not necessarily the cost of a whole new chainset when only the left crank needs to be replaced.

 

[gmw492]

For two teeth your chain would probably work fine as it is. It’s not so finely tuned that chains have to be an exact length to work just fine. Have you considered a left only crank and keep the chain set you already have?

Since my post yes I have , seeing as it’s my first power meter and experience I am thinking of trying that seeing how it goes ,thanks

 

[gmw492]

[QUOTE................
Umm, yes! The OP wants a crank based power meter.

But not necessarily the cost of a whole new chainset when only the left crank needs to be replaced.
[/QUOTE]
Yes since had a look into that thanks

 

[gmw492]

You're proposing an expensive change. Unless you live in a hilly area or are struggling on the hills, then I'd question the need to change the whole chainset. There's always the option of a cassette with more hill-friendly cogs if there's only a few problem hills in your area and you need other options to consider.

Yes true looking at left only also now , thanks

 

[gmw492]

Thanks for the info guys, I’ve opted for a cheaper option and gone for the left side power crank, got a new 4iiii precision 3D for £240 , my first power meter so took the comments on board , cheers