Noobie Bottom Bracket Question
 

I'm building my first bike, learning as I go. I've been browsing eBay looking for an affordable bottom bracket for my steel Univega Gran Sprint frame. I know it's British threaded, but my question is can I mix and match a spindle with the bearings/cups? Can anyone tell me if a Suntour Sprint 68 mm x 109.2 mm spindle will work with generic SR Suntour cups and bearings and a SR crank? I'd appreciate any help!

Also, is there any rule of thumb to know what length spindle I need?

The spindle & cups should work together.
You just have to determine the spindle length your crank requires and then FIND one.
Probably easier to just get an inexpensive Cartridge BB.

If you have a 68mm English threaded BB shell and your crank arms are JIS taper, save yourself the trouble and buy a Shimano UN26 sealed BB in 68x110 for $13 Universal Cycles -- Shimano UN26 Bottom Bracket. Better yet, splurge and get the UN55 Universal Cycles -- Shimano UN55 Bottom Brackets for $10 more.

Thanks guys. Is there any disadvantage of going this route instead of finding a bottom bracket from the time period my bike was made? Also, how would I determine what spindle length I need? Crankset is a double. Crank arm length wouldn't matter right?

Spindle length is determined by the specific crankset you are using, but you need to start from the back and determine the chainline, so that you can match it on the front. There are too many combos to easily know which spindle length will fit, especially with an older crankset. You may need to dry fit a spindle and your cranks to see what is needed.

Frankly you are better off buying a crank and spindle together. Building a bike from scratch is either a headache or a wallet drain - or both. It's a very inefficient way to get on the road or to learn a lot about bike maintenance.

A conventional cup and cone BB will almost always be lighter than a cartridge BB, unless you are comparing a very low end cup and cone BB against a very high end cartridge BB, and even then the cartridge BB may be heavier (carbon spindles don't count unless both BBs have the same type of spindle).

The spindle length is dependent on the combination of the frame AND the crankset you are using. The chainstays may be bent, flattened, and/or ovalized, and that can affect how much spindle width you need for the inner chainring and the crankarm to clear the chainstays.

What I do is install a BB and the crankset, then check for adequate clearance of the inner chainring, and the crankarms, and then last check the chainline to see if changing the spindle length is necessary or desirable to improve the clearance, or the chainline.

Clearances FIRST. Because without adequate minimal and proper clearances, who cares if the chainline is what the manufacturer recommends or not, you will not be rotating the cranks anyway.

It depends how much you value "correctness". If you just want a riding bike go with a cartridge, if you're making a museum piece use the old style. As far as length you can either search for documentation on your crank or just go ahead and install it on a known spindle and do the math to determine how much it needs to move.

You have to keep in mind that a "correct length" spindle may be hard to find.

Given the possible range of worst fitted spindle lengths and that only one or two will be best this is one time I strongly suggest that a LBS helps you. They will have a selection of different length at hand and can, as some have mentioned, dry fit to test a length with your crank arm. If you were to ask them to only determine the spindle length that you would buy from them the labor cost should be less then if they also did the rest of the install. This way you get to do your own install with the best fit the first time and not suffer the chance of extra time, return shipping cost of using a mail order/on line source. Especially with an older crank set the spindle length is likely to be longer then most current ones use. Without more info I'd think a 118 to 127 spindle length would be most likely to be the range you'd work with. A photo of the rank would sure help. Is it a straight arm or a low profile curved one? Is it a double or triple ring? How much stay sculpting is present and do the indents line up with the rings? An experienced shop can see all and likely pick the best fit the first or second time then dry install a BB. You at home, depending on who's advice you listen to, might need 3 or 4 trials. So how much does it cost to return a BB and how long to get another times the number of attempts against the cost of the shop's labor? But since you have no location in your profile my advice might not be practical and no one will know that. Andy.

I'm glad I asked, because I had no idea it would be this big of a process, haha. I like the taking it the local bike shop option, but I'll probably post some pictures later to see if that narrows it down. I really appreciate the advice from everyone. :thumb:

If there are any markings on the spindle, it would be most helpful to show those.

http://bikeforums.net/attachment.php...hmentid=422322

Here she is. It's a SR Sprint double.

Well that didn't turn out so well. Here we go:
http://bikeforums.net/attachment.php...hmentid=422328

Edit: Thought the first one was too small. Same picture.

as mentioned, i'd just take the bike (with the BB and crank, if it has been removed) to the LBS, plead ignorance, throw yourself on their mercy and ask to buy a cartridge BB to fit. they may offer to remove that nasty old fixed cup and install the new BB. if so, it may not be a bad idea to take them up on it. :)

IME, it's just too subject to error trying to give advice on what EXACT BB/spindle length to get for particular old crank. of course it's less error prone if one knows, as we all do, that it is a two-chainring road crank. but even then....

Now that you actually stated which crank you have, did you try Google?

http://www.bikeforums.net/bicycle-me...-question.html

I checked Sheldon Brown, but he didn't have any info on SR cranksets. I didn't even think to search such a specific question. Thanks a lot!

"3S" or "3SS" or "3T" spindles are commonly used with double ring cranks of that type. You may need to experiment to get the best chain line.