Building up first SS, need some advice on BB + crank dimensions

Ok, noob alert here...

I am buying parts for my first SS road build, a On-One Il Pompino.

1. What BB width do I need? According to On-One it's a 68mm, BSA (English) thread BB, but they mention nothing about how to choose the correct width

2. I am 6ft4, which crank length should I go for? Is it very important to get the correct length, even if it's just 2.5mm different?

Will probably have more questions to come.

Thanks.

Chris

Yes.

BB width will depend on the crank set you use, you lbs should be able to help you when you buy your crank set.

bb width is 68mm, spindle length depends on the cranks.

crank length, http://www.sheldonbrown.com/cranks.html

Ok, noob alert here...

2. I am 6ft4, which crank length should I go for? Is it very important to get the correct length, even if it's just 2.5mm different?

Doesn't matter too much and won't really match up to your specific height. Not like sizing a frame. Fixed riders often like the shortest possible available crank to avoid pedal strike. Your choices with widely available cranks aren't huge anyway. 165mm, 170mm, 175mm. Height of the bottom bracket in the frame can also make a difference if pedal strike is a problem. If ou already have a frame then BB is where it is, so not worth worrying about. It's important for some, not for others depending how, what and where you ride > http://www.londonfgss.com/thread5606.html

As already mentioned. Spindle length and type will depend on cranks you're fitting.

Ah, or if you have a bike with a high BB shell, then the longest cranks for skidding leverage.

165mm, 170mm, 175mm.

it is possible to get in between sizes like 172.5mm, and the length goes up to at least 180mm.

True, but I'm imagining he's not going to spend loads on cranks for a first SS build and was just talking about the most widely available eg, Sugino and other cranks that people tend to use for first builds.

True though you can get other sizes and 180mm which might give you more torque if it's SS and you're less worried about pedal strike than a on a fixed.

Also just got the impression that the OP was trying to ask and match his height to a crank length, which might be beneficial but not as crucial in the way that frame size is.

2. I am 6ft4, which crank length should I go for? Is it very important to get the correct length, even if it's just 2.5mm different?

Everyone's built with different proportions, but I'm 6ft 4 plus and find 175 cranks suit me well. I wouldn't say 2.5 mm makes enough difference to notice, but 5 mm does. Since it's a SS bike you're building (rather than fixed) 175 mm cranks won't give you any problems cornering as you can freewheel if necessary. In any case, 175 mm cranks don't give me problems cornering on my fixed as (a) I use fairly slim pedals with good ground clearance, and (b) I don't go crazy around corners anyway.

For your height, I don't think you'd go far wrong with 175 mm cranks.

Thanks all for the advice.

2 points:
1) Advantage of 170mm (and longer) is that there is a greater choice out there (and so you may find it easier to keep costs down if that's important). If you are thinking that you might go fixed gear in the future, you may want to consider shorter cranks - there is a good thread somewhere on LFGSS with lots of BB height / crank length combos that people find to work OK on fixies.

2) Have you got another bike that you ride regularly at the moment? If so, you may want to stick with the same length cranks as what you've got already as you will be used to the feel of that.