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Bottom Bracket Noob Help
#1
Hi guys,

1 post be gentle lol, basically i'm trying to create a fixie for my brother for his birthday. Using old bike parts from my dad. He used to be really into bikes and has loads of old parts etc.

Basically i've got a semi decent frame, and the bottom bracket uses cotton bolts? Sorry if this is the wrong terminology i'm trying to remember what my dad was saying. I want to replace this old bracket with a new one then replace the crank also. If I buy a new a bracket will it just be a straight fit? Is there a standard size etc?
If so could some one link me to a cheap one and a single gear crank.

Sorry if this doesn't make sense i'm trying to read as much as I can, and get bits of info of my dad,

Thanks

Chris
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#2
He probably meant "cotter pins" which was an older way to attach the cranks to the bottom bracket. (http://www.sheldonbrown.com/gloss_cn-z.html#cotter see: "cottered cranks")

I don't think you can easily buy a new bottom bracket to fit cottered cranks and you can't mix cottered and more modern parts. So you would probably need to buy a new bottom bracket and crank at the same time. There will be plenty to choose from, but there is not a single "standard size".

Here's a couple articles about converting to fixed to get you started. These are a fun project so don't get put off.

http://www.sheldonbrown.com/fixeda.html
http://www.cicle.org/cicle_content/pivot/entry.php?id=1572
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#3
Thanks very much for the info, there cotter sorry! Ill have a read and come back, might post a log if i can find my camera,
thanks again
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#4
Hi, Back again.

Today I dropped the frame off at a local paint strippers after removing some of the excess bike pump clips and brake clips etc, and also cleaned up a nice old stem of my dads, which took longer than expected

I dropped into my local bike shop today for some help, the guy kindly removed my bottom bracket, he said the replacement would be 68mm but he didn't know the other length as he said that I would first need to purchase my chainset to allow me to get the correct chain tension?

I'm hoping to buy both a bottom bracket and a chainset asap possibly of ebay, so looking for some advice on purchases.

http://www.chainreactioncycles.com/Models.aspx?ModelID=2647

Would that do for the chainset? What size would I need if im trying to make a fixer?

And what bottom bracket size would a need 68mm and 1??mm

http://www.chainreactioncycles.com/Models.aspx?ModelID=34653

Sorry for all these lame question I just really want to crack on and I need parts lol

Also if in the wrong section please mods move,

thanks again

Chris
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#5
(02-26-2010, 12:02 AM)chrisnic0 Wrote:  Hi, Back again.

Today I dropped the frame off at a local paint strippers after removing some of the excess bike pump clips and brake clips etc, and also cleaned up a nice old stem of my dads, which took longer than expected

I dropped into my local bike shop today for some help, the guy kindly removed my bottom bracket, he said the replacement would be 68mm but he didn't know the other length as he said that I would first need to purchase my chainset to allow me to get the correct chain tension?
He meant probably the chain line. 68mm is the width of the bottom bracket shell, the other interesting length is the axle length. Check e.g. http://www.sheldonbrown.com/chainline.html

Quote:I'm hoping to buy both a bottom bracket and a chainset asap possibly of ebay, so looking for some advice on purchases.
Unless you really do know what you are buying, ebay is not a good place to look. The parts are usually ridiculously expensive.
Quote:http://www.chainreactioncycles.com/Models.aspx?ModelID=2647

Would that do for the chainset? What size would I need if im trying to make a fixer?
You'd rather need a crankset with only one chain ring for a fixie (well, it mostly just looks better). But you could just remove one chainring and get new chainring bolts (half width).

Quote:And what bottom bracket size would a need 68mm and 1??mm

http://www.chainreactioncycles.com/Models.aspx?ModelID=34653

Sorry for all these lame question I just really want to crack on and I need parts lol

Also if in the wrong section please mods move,

For the axle length try looking here: http://www.sheldonbrown.com/bbsize.html
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#6
Thanks very much for the reply mate, ill have a read and see how i get on,

In regards to the chainring i was going to remove the smaller one? Do you know where I can buy specialist fixie parts in the UK, i couldn't find any single ones,

Thanks again for the links

Chris
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#7
OK judging by the sheldons guide I need a 42mm chainline?
My frame spacing is 120mm, would this be correct chainline?? He shows a guide for a double chainline and a triple but not for a single would this be different?

I thought this would be easy but I think Im taking in too much info as I knew literally nothing about bikes 2 days ago lol. HELP!!
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