Cranks-BB

[cdfeto]

Hi,
my brother recently got hand of an old road bike, equipped with a RX100 groupset. Only problem is the cranks ... the cranks are dead (threads are gone and theyre bent).

I measured the BB shell width: 73mm and then looked up the different possible BBs and it seems that the only 73mm wide BB are the standard english BBs. Am i right? So its the equivalent of the nowadays: Euro BB?

and if anyone has a pair of cranks and or BB that might fit that description, im might be very interested.

cheers

[tomac]

double check the shell width. Oversize BBs (73mm) were not that common on road bikes. It may be though. Is the bike an Italian brand? if so it may be an Italian threaded 70mm BB shell.

Euro BBs are what BMXers call English/ISO bb shells. 1.375/1.370" * 24tpi threading.

What is wrong with the current BB? Can you get the cranks off and measure the BB spindle width?

...or maybe you don't have to...

RX100 7 speed (1990-1993, date stamps O*, P*, Q* or R*) used a 113mm JIS (square) BB spindle)

RX100 8 speed (1994-2000, date stamps S*, T*, U*, V*, W*, X* or Y*) used a 107mm symmetrical JIS BB

and RX100 triple used a 122mm JIS BB.

- Joel

[cdfeto]

really sorry bout that, i guess i just wanted it to be 73mm
i re-measured it and it seems to be 68 mm wide

Im not sure what the make is, theres a clean-spot left from when the sticker had been taken off and i think it says: Quantun.
HAd a google but couldnt quite get a brand with that, or similar name.

The BB might just needed a good clean as its a bit stiff but its not too bad. I cannot take the cranks off at this stage as i dont have the necessary tools.

Im not sure what cranks they are, as they have no wirtting on them but the following is engraved on the back side of the arms:

FQ-A300
Shimano
VIA Japan

thanks for the awesome and fast reply Joel, as usual

[tomac]

OK they're not RX 100 then, probably about an Exage level basic. Which may mean they'll use a longer BB spindle to save on machining costs.

- Joel

[tomac]

I presume that quantum is a nothing-special brand, but there is a nice custom builder out of perth called quantum.

- Joel

[cdfeto]

does that sound right for the BB measurement?
if i keep my BB, are there any measurements i should do (chainline, spindle lengh)?
what kind of cranks should i be looking at, im on a low budget, the rider will be 60kg and the bike will be ridden a few times a week.

ive seen a couple of MTB square taper cranksets on the net which are in my price range, could that be an option? any dissadvantages appart from the fact that i will have to get new chairings (current 5bolt)?

[tomac]

I probably have something kicking around. Suntour cyclone or shimano 600 or similar.

The important BB measurement is the spindle width, which you have to remove the cranks to get. Conundrum!

- Joel

[cdfeto]

Ok, the spindle lenght is 140 mm. BB needed some work but its all good now. Please let me know if you have anything that i could use and what you wnat for them.

cheers

[tomac]

are you serious? that's huge. Are you measuring it from end to end? Are you sure it's a square tapered Spindle?

- Joel

[cdfeto]

sorry bout that, again.

i measured the spindle from end to end, but it has this thread at the very end. so the actaul spindle measurement is 118 mm (pretty sure, didnt have a slide caliper).

sorry bout that, again

[cdfeto]

would any of your spare cranks fit?

cheers
please pm me your number or email if they do

[tomac]

I'm sure they would. 118 sounds much more likely. I'll see what I have. Are the chainrings on your current cranks serviceable?

- Joel

[cdfeto]

Sweet.
Im pretty sure the chainrings ( 52t and 40t) are bent but the teeth are looking alright.
A phone number would be really convinient, if you dont mind.

thanks again

[tomac]

0431 436 225 is my contact Chris. I'll be doing some garage stuff today will look out as I am rummaging then.

- Joel

[cdfeto]

pics of the Quantum should be up soon, camera problems