# Help with new crankset BB ?



## sick1 (Jul 6, 2010)

We need to replace the crank set on my son's Cannondale F8, and I'm not sure what type of BB this is (total noob, sorry), or what type of crankset will work. BB30? square taper? Apologize for the grainy pics, any help would be appriciated. Thanks.


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## JasonInBTR (Jul 19, 2010)

I would guess it is a square taper. Pull one of the crank bolts and it will be obvious. If you are upgrading the crank I would probably just swap the BB out while your at it. Looks like the current BB is a FSA TH-7420ST and the crankset is a SR Suntour XCC-T202PB. More than likely the BB is a 68mm english but you won't know till you rip it off. Will need a puller to get the crank arms off.

Jason


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## AndrwSwitch (Nov 8, 2007)

Don't worry about keeping the bottom bracket. They're a $20 to $30 part, and nicer cranksets come with them anyway lately.

Cannondale sometimes uses some weird standards, but I think everything about the F8 is pretty standard. That doesn't look like BB30, and typically only higher-end bikes have that standard.

You do need to know the width of the shell - that's the part of the frame that the bottom bracket screws into. It's probably 68mm, but might be 73mm. You can just put a tape measure or a ruler to it - that's one of the few measurements on a bike that's an actual measurement of something.

If you're getting a crank with an outboard bottom bracket, you should be able to get the shell faced, drop the new bottom bracket in, and go. Depending on bottom bracket shell width, you use a different number of spacers. That'll all be in the instructions.

If you're getting another crank that attaches to a conventional bottom bracket, you need the appropriate bottom bracket for your shell width, the interface type, and the spindle length specified by the manufacturer of the crank. For example, a bottom bracket might be described as

English Threaded, Octalink, 68mm * 118mm. That means it goes in an English threaded bottom bracket shell (almost all current road and mountain bikes) that's 68mm wide. The other two specifications have to do with the crank - the 118mm is the spindle length of the bottom bracket, specified by the crank, and "Octalink" refers to the way the crank attaches to the bottom bracket. There are other standards, but I don't think it's worth debating the virtues of one over the other. Just make sure you match the bottom bracket to the shell width and specifications of the crank.

Are you planning to install it yourself, or have the shop do it? For me, it's usually a shop job because it requires a crank puller, and non-destructive removal and installation of bottom brackets requires a special tool that fits into the bottom bracket housing. Outboard bearings are much easier to work with - they only need one special tool, and a lot less force.


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## sick1 (Jul 6, 2010)

Thanks for the replies. Measured the BB width at 68mm. Will take to LBS to have installed unless my neighbor has a crank puller, will have to check with him. So we can put in any BB as long as it's 68mm? Any recomendations on which crankset?


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## theMeat (Jan 5, 2010)

Grease the spindle and put blue lock tight on bolts. Tourque bolts to crank manufacturers spec and check or re-tighten after each of first few rides. If you hear or sence any movement stop riding cause it doesn't take much to ruin an aluminum square taper crank.


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## perttime (Aug 26, 2005)

Why do you _NEED_ to replace it?


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## JasonInBTR (Jul 19, 2010)

Should be able to use any english 68 BB. Recommendations are going to depend on the usage. Anything from a reputable manufacturer should be good. I use a Truvativ 2.2 Stylo because I found that I never use my big ring and would rather have a bash. You will find cranksets starting below $100 and go up well over $500. Increase in cost is usually due to decrease in weight and use of more exotic materials or increased durability.

Jason


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## rlouder (Jun 26, 2007)

If there's nothing wrong with the bb (ie, the crank arms aren't loose) the Shimano Acera M361 would be an upgrade and should fit since it requires 122mm spindle. All you need is crank puller to change it.

http://www.amazon.com/Shimano-Acera-175mm-Square-without/dp/B00288JWH4/ref=pd_sbs_sg_2

http://www.amazon.com/Park-Tool-Pul...=UTF8&s=sporting-goods&qid=1280768053&sr=1-19

Of course, you can spend as much as your budget allows. Better ones are better.


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## sick1 (Jul 6, 2010)

perttime said:


> Why do you _NEED_ to replace it?


The pant leg of his jeans got bound up in the crank and bent the outer chainring, tore up the jeans pretty bad too, and 2 teeth are busted off the middle chainring, we're not sure exactly how that happened. He has SRAM x.o rear dr, x.9 front dr,(not installed yet) 990 11-34 cass, x.o shifters and was going to upgrade the crankset eventually anyway, we just weren't planning on doing it so soon. He has $300 or so to spend on a new crankset.


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## perttime (Aug 26, 2005)

Maybe Shimano XT cranks and external BB would do.


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