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I’m building my first road bike and so far I’ve purchased a 2004 Look KG 461 carbon frame and a set of 32 spoke Ultegra 6600/Mavic Open Pro wheels.
I’m getting ready to order a complete Ultegra 6600 Group (minus the hubs) and I would like to know if the (Shimano Ultegra Bottom Bracket Cups SMFC 6600) that come with the group will fit my frame. The information that I have for the frame states that it has a 68mm Bottom Bracket. Does the 68mm refer to diameter or length? And do bottom brackets come in different diameters and lengths? And do the Look frames take English thread or Italian thread bottom brackets. (I’m confused because the frame is French)
Also, once I complete the build and want to trim the steering tube to length (Look HSC4 Carbon Fork with Carbon Steerer) what’s the proper way to trim the Steerer Tube?

One more question: How much of a difference does Crank Length make?
I'm 45 years old 6'-1" 210# and I ride 40-50 miles/wk (I plan on riding more with the new road bike) I was planning on a 53x39 Crank, 12-25 cassette and 172.5mm crank length.
 

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check out park tool...

Nardog said:
I’m building my first road bike and so far I’ve purchased a 2004 Look KG 461 carbon frame and a set of 32 spoke Ultegra 6600/Mavic Open Pro wheels.
I’m getting ready to order a complete Ultegra 6600 Group (minus the hubs) and I would like to know if the (Shimano Ultegra Bottom Bracket Cups SMFC 6600) that come with the group will fit my frame. The information that I have for the frame states that it has a 68mm Bottom Bracket. Does the 68mm refer to diameter or length? And do bottom brackets come in different diameters and lengths? And do the Look frames take English thread or Italian thread bottom brackets. (I’m confused because the frame is French)
Also, once I complete the build and want to trim the steering tube to length (Look HSC4 Carbon Fork with Carbon Steerer) what’s the proper way to trim the Steerer Tube?

One more question: How much of a difference does Crank Length make?
I'm 45 years old 6'-1" 210# and I ride 40-50 miles/wk (I plan on riding more with the new road bike) I was planning on a 53x39 Crank, 12-25 cassette and 172.5mm crank length.
The Park Tool website has lots of good, general build and repair info.

http://www.parktool.com/repair/readhowto.asp?id=111

Your frame takes an English BB. That's all the specification you need.

When first assembling the bike, be sure to leave enough steering tube length. LOOK provides 3cm of spacer with the frame. That's the maximum that you can use with the extended top headset. If you're real sure of the stem angle and spacer combo you need, the steerer can be cut to final length, but a less experienced rider should use 3cm of spacer to start with and later cut the steering tube to final length.

Use a new (sharp) 24 or 32 tooth per inch hacksaw to cut the steerer. To be sure you get the right length and cut a straight line, assemble the headset, spacers and stem. Press firmly on the stem to seat it against the spacers and lightly tighten the steering tube clamp bolts. The use a sharp tool to lightly scribe a line at the top of the stem. At this point, you have two options, cut the steerer 2-3mm below the line, or cut it 2-3mm above the line and place an addtional 5mm spacer on top of the stem. To make the cut, it's easiest to remove the fork and clamp the steerer gently in a vise. For upmost safety, I have a piece of wood with a 1-1/8 inch hole drilled through it, that has been sawed through the middle to create padded vise jaws. I make a shallow cut around the tube, about 45 degrees at a time, carefully following the marked line, then cut around the tube a second time, going all the way through. Cuts from top to bottom are more likely to be crooked, unless a special sawing guide is used.

Crank length depends on your leg length and pedaling style. Most likely 175mm would be the choice for someone of you height, but if you're a spinner, maybe shorter cranks would be the better choice.
 
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