The BB on my Vulcan has died.

it says on it

BC-73C
68+1.5
BC 1.37x24T
115M
L R
What does all this mean?!

The L came out the crank side which surely is the right side of the bike?

Is this a direct replacement? Is it worth spending any more.

http://www.ebay.co.uk/itm/Shimano-Sealed-Catridge-Bike-cycle-Bottom-Bracket-Square-Taper-New-VARIOUS-SIZES-/231090110019?pt=UK_sportsleisure_cycling_bikeparts_SR&var=&hash=item35ce0b3e43

BTW I weighed the old one and it came in at 285grams… is this heavy?

68 or 73 would be the width of the bottom bracket shell. As it states both I’d measure it just to be sure. 115 is the length of the spindle.

If I were replacing a square taper bb I’d go for one of these over the UN26 on ebay, even if it is a penny under the crc free delivery threshold…

http://www.chainreactioncycles.com/shimano-un55-square-taper-bottom-bracket/rp-prod71369

so if I went for a 118 the crank would sit out another 1.5mm?
Thanks for your help

The crank sits a little too close to the frame which prevents the mech front changing efficiently (I’ve adjusted it to death and tried multiple ones).

http://www.halfords.com/cycling/cycling-parts/bottom-brackets/vp-bc73-68-x-118-square-taper-cartridge-bottom-bracket

yeah that should be fine but it will affect your chain line slightly and your gears will need to be re-adjusted including the limiter screws on the front mech

I’d stick with Shimano BBs, the square taper ones last for eons. 🙂

possibly worth ordering some 8mm allen crank bolts to go with a new bb. They don’t always come with them and often they’re the hex bolt type.

So will the halfords one i found definately fit?

Thanks for your help.

Btw whats the l and r for? Should the l be in the crank side?
Thanks

On paper yes but it looks suspiciously like a dead one I removed from my commuter after less than 6 months use. it didn’t fit so well as it had a big gouge all the way around the body from the screw that holds the bb shell cable routing fitting in place.

Seriously, Shimano. 😉

no idea on the L/R I’m afraid!the threads on both sides (and for the crank bolts) should be RH so I’m not sure it matters. If I’m wrong I’m sure someone will correct me.

BC 1.37x24T is the thread, British in this case
If L and R doesn’t refer to the cup side then it refers to the thread direction on that cup

^ Correct, it is a LH thread on the drive side, my mistake, sorry. 😳

that makes sense now thanks.

its all back together now with shimano and working like a dream 🙂

now the next problem the rear Q/R is bent! This Vulcan was a VERY bad buy… pretty much everything on it was broken lol

Are you sure it’s a square taper? Most Vulcans I’ve seen come with truvativ isoflow, which is a similiar format of BB but not compatible with any Shimano bb.

its got square pedals bit on it

definitely fits like a glove