Hi,

I just bought a new Vintage 1980s bike frame. How do I know which Bottom Bracket to use for the new frame? Sorry, I'm new so I may ask some stupid questions.

I plan to use this for a Fixie, mainly Road Touring, just biking to work, mostly on flat ground.

well, bottom brackets have to match both the frame and the crankset you want to use.

so... what crankset are you using? and what size is the frame's BB shell, with what threads?

the BB shells on classic bikes are most commonly 'british 68mm', but some frames, especially french, can be all kinda other stuff.

cranksets can be square taper (classic, standard for decades, but there's ISO and JIS tapers... ISO is mostly Campy, JIS is Shimano etc), or octo-whazza (shimano and sram's versions of this are different), or 2-piece, where the BB is integrated with the crankset (fairly common on the newest road/mountain higher end stuff like Ultegra, XTR).

+1 Crank and BB are a pair, buy them as a set.

There is about a 99% chance that you have a standard 68mm English-threaded bottom bracket shell. The other smaller possibility is that your frame is Italian threaded, or possibly French or Swiss. This is something that you have to know, so do some research based on your frame specs.

Just as important as this, you need to know what are going to use the bike for. Loaded bike camping over gravel roads in the Alps, where you'll need very low gearing, or doing high-speed pavement runs in Florida? You will pick your crankset based on this. Finally, you'll need to know what kind of drivetrain you want to run. 7, 8, 9, 10 or 11 cogs? Or a single speed or fixed gear? Your choice. More cogs are not necessarily better, as an 11-speed chain costs about 5 times more than a 7/8 speed chain for no obvious reason. Keep in mind that if you are riding any kind of miles, you'll be replacing chains several times per year. Factor this into your economics. Plus a decent used 7-speed crankset can be picked up at my local bike Co-op for about $20. Any 11-speed crankset will cost a minimum of $400. And in the end, 7 carefully selected cogs at the back are more than enough.

Thank you all. I think it's best that I take this frame to my LBS and get a new BB with matching Crankset. That's the better way, right?

what sort of crankset are you planning on putting on this frame? is this a road racing or road sport or road touring or track/singlespeed or mountain bike or cruiser or hybrid or what?

all you've told us is its a 'new' 1980's frame. there's a LOT of room for variations there.

measure the BB shell width, most typically thats 68mm. also measure the rear axle spacing between the inside of the dropouts as that will constraint what rear wheels you can use and how many gears you can run, I'd expect that to be 126mm or 130mm if its a road frame, and 135mm if its a mountain frame....

Pierce,

I plan to use this for a Fixie, mainly Road Touring, just biking to work, mostly on flat ground.

What brand is the frame? There's no way for us to know what kind of BB it had without that.

ok, fixie cranks are mostly square taper JIS. IF the frame is BS (british standard) 68mm, then you likely can use a Shimano UN55 or similar cartridge BB and be done with it. if you buy this at a local bike store, they'll probably install it in the frame for just a few $, otherwise you'll need a BB tool/ A 3/8" drive torque wrench is highly recommended to do it right (also use for torquing on the crank bolts)

btw, fixie != touring. a touring bike tends to be a heavy duty road bike, with wide range gearing, generally triple ring front, and a relatively long wheelbase.

Pierce,

Thanks. I thought Fixie is like touring around. I'm new to this and still learning everything about bikes. Do I use a tape measure or some type of digital caliper to measure the BB?

You might want to take a look at the BikeForums' "Singlespeed & Fixed Gear" thread for more info. and advice on building a fixie;

https://www.bikeforums.net/forumdispl...mp-Fixed-Gear?

This "SS & FG" thread is located in the lower part of the BF home page.

Good luck with your fixie build!

Will do, FMB42. Thank you.