Drivetrain, crank, BB...persevere or replace!

[Rawcas]

I'm currently updating my daily commuter with some new bit's and pieces after many years of faithful service, it's a '94 Carrerra which I have posted up previously.

I have purchased and fitted a new square taper BB as I didn't want to give up the old 7 speed drive train (even though it is Grip Shift) and was due to refit the chain set today...however, I came across a rather stubborn pedal which had to be removed (the originals are totally knackered)....turns out that the left crank's pedal had been cross threaded from day 1 and it has consequently stripped the thread upon removal meaning I can't fit my nice new shiny SPD's in it's place!

So, what to do. Do I just lump it and buy a random no name left crank to replace it and accept the fact that I will no longer have my original drivetrain intact in nice matching order...or do I take the opportunity to upgrade whilst the bike is stripped down?

If I upgrade could I go for a 9 speed set up? Will the dimensions of an older frame/limitations of an older rear hub allow me to fit 9 speed?

I only ask about 9 speed as I have a set of early Deore 9 speed Mega 9 shifters with combined brake levers sat in the parts pot at the moment. What chainset, cassette and derailleur would I need to match (appreciating an upgrade to a hollowtech BB would probably be a good move as well)?

Any thoughts?

 

[oldave]

In simple terms, as long as shifters and chain numerically match the cassette, then just about anything will "fit" (I am assuming that rear drop out spacing is 135mm).

For example, my '93 ish Saracen is running original 7 speed c'set, 9 speed rear, 9 speed rapid rise rear mech, SLX front mech, 9 speed chain and 7 speed thumbies (non-index setting obviously!). And I can swop back to original 7 speed wheel without altering anything else!

 

[oldave]

Missed this bit: "Will the dimensions of an older frame/limitations of an older rear hub allow me to fit 9 speed?"

As above, frame almost certainly OK, freehub might well NOT be. Could PROBABLY fit a 9 speed freehub - the least straightforward bit of the upgrade.

 

[Rawcas]

Hmm, interesting.

After a day of skinned knuckles and much swearing at the cross threaded crank I think I'm almost ready to ditch the 7 speed set-up. Never been totally convinced by the Grip Shift either and the gear change before I took everything off the bike was anything but smooth even when fully 'adjusted'....think I was just looking for the easy option which would have been to keep it.

So essentially any chainset will do the trick as long as all other components in the drive train are 9 speed...time for a trawl through the classified's and Ebay I reckon

 

[NeilM]

One thing to watch is crank length. It is not as critical as some think, but cranks come in different lengths, 160, 170, 175, 180 etc. Take a look on the back of one of your existing cranks arms, and somewhere you should find the length. When you get your replacement cranks, look for the same length.