Replacing the Chainset on my Secteur Elite

[phil_hg_uk]

I want to upgrade the chainset on my Secteur Elite to 105 I had a look at what is available and found this:

http://www.cyclechat.net/index.php?app=forums&module=post&section=post&do=new_post&f=23

my question is which one do I need as there seems to be 4 different sizes 165mm, 170mm, 172.5mm and 175mm and what does this measurement refer to, also do I need to also change the bottom bracket for this one for instance:

http://www.chainreactioncycles.com/Models.aspx?ModelID=11726

or is the one on the secteur elite ok for this.

Also am I correct in thinking that if I undo the bolts on the non drive side of the crank and the remove the cap and knock the spindle through then the drive side will just slide out then refitting reverse of removal.

 

[TheDoctor]

The 165/170/175 thing is the length of the crank - distance from the BB axle to the pedal axle. Unless there's any reason you want a different length, go with the length you've already got (which should be marked on the back of the crank).
Bolts out, cap off and the crank should come off easily. Give the BB axle a tap with a mallet / lump of wood and it should just push through.
If the BB in there is Shimano, you should just be able to use it on the new crankset.
Honestly, swapping cranksets is a piece of cake these days. Took me 20 mins to swap a 105 one for a compact.

 

[phil_hg_uk]

I would like to thank everybody for all their help Thank you for your help doctor I have ordered the 105 triple chainset in black and the tool for removing the crankend screw in thingy so I now await the arrival of the shiney bits

 

[TheDoctor]

Mmmmm shiny things!!!