Upgrading bottom bracket/chainset

[Rip Van]

Newbie on here.

I have a Dawes Giro 300 which I use for commuting/training. The bottom bracket (square taper) has developed play. The original equipment is Shimano Sora 7 speed 52/39. I would like to upgrade to Sram Rival chainset (crankset?) and bottom bracket, which I have on my other bike. Could anyone tell me if it's possible to do this, assuming the bottom bracket width and thread pitch are the same (which I'll check)? I believe, if I fit a compact chainset I would have to fit a new front derailleur. Could anyone confirm this?

 

[PpPete]

Sounds like expensive kit on a cheap frame....perfectly feasible to do but is it worth it? In theory you should have the BB shell faced before fitting outboard bearings - but you may get away without it.
If the Rival chainrings are also 53-39 you shouldnt need a new front mech. If you go to 50-34 compact chainrings I'm not sure if the Shimano mech will take it, you would certainly need to move the mech down a few mm.

 

[jpembroke]

On that frame I reckon I'd replace the BB with Shimano UN54 square taper (£13) and get a Stronglight Impact compact chainset:

http://www.ribblecycles.co.uk/productdetail.asp?productcatalogue=STROCHAR560

Only £53 and available in loads of different formats (50/34, 50/36, 48/34) and crank lengths.

I just can't see it's worth putting an expensive chainset on a bike like that really.

Oh, and the 105 front mech I have works with both compact and standard chainsets.

 

[Rip Van]

Thanks chaps. I guess you're right. I'll save some cash and just change the BB for the moment.
Wouldn't she be pleased if I told her...but then I'd probably have to explain every package that arrives.