A friend of mine is trying to convert a bike to a fixie. It currently has an LP20 BB with a 118 designation on the axle. It is rough and needs replacement.
Questions: - Can he pull this out and use a conventional Shimano unsealed 68/113 unit from the 80's? Is there anything special about a BB with an LP 20 in it? Is an LP20 a square taper?
- will his chainline be close enough with a 113 in there? Or does he need to get down to a 110 to make it work? Could he just put a couple mm of spacers behind the (new) single rear cog to make it line up?
A friend of mine is trying to convert a bike to a fixie. It currently has an LP20 BB with a 118 designation on the axle. It is rough and needs replacement.
Questions: - Can he pull this out and use a conventional Shimano unsealed 68/113 unit from the 80's? Is there anything special about a BB with an LP 20 in it? Is an LP20 a square taper?
- will his chainline be close enough with a 113 in there? Or does he need to get down to a 110 to make it work? Could he just put a couple mm of spacers behind the (new) single rear cog to make it line up?
Thanks,
Everything should be fine. The LP20 is a bottom-feeder square taper BB. The conventional BB will replace it without a hitch. If you want to get finicky, run a tap through the threads and face the BB shell before you install the "new" BB.
A friend of mine is trying to convert a bike to a fixie. It currently has an LP20 BB with a 118 designation on the axle. It is rough and needs replacement.
Questions: - Can he pull this out and use a conventional Shimano unsealed 68/113 unit from the 80's? Is there anything special about a BB with an LP 20 in it? Is an LP20 a square taper?
Yes, just get the length needed for the fixie chainline. Standard JIS square taper, made today as well(UN-53/73). LP-20 just a low end BB.
Quoted message said:
- will his chainline be close enough with a 113 in there? Or does he need to get down to a 110 to make it work? Could he just put a couple mm of spacers behind the (new) single rear cog to make it line up?
Put spacers onto the hub and if there are not enough threads engaged, you may strip the cog/hub. Go to a decent bike shop, ask for a proper length BB and let them 'spec' it for you./ We do that all the time,,put some BBs in, with the crank, and see what is the best length.
,put some BBs in, with the crank, and see what is the best length.
Follow up length question: How come the LP20 is commonly a 118? I'm used to that length for classic French, but I thought 113 was the buzz for Shimano... or is this a less than common LP20?
put some BBs in, with the crank, and see what is the best length.
still me said:
Follow up length question: How come the LP20 is commonly a 118? I'm used to that length for classic French, but I thought 113 was the buzz for Shimano... or is this a less than common LP20?
LP20 was the oem unit when cheap (matching quality) cranks commonly used 115, 118, 122, 127mm so it was made in those sizes. Shimano didn't make a 103mm LP20 because they didn't supply it to manufacturers for use with the DuraAce crank of the period.
I think sometimes it's overlooked that oem drives all these decisions. The aftermarket parts market's only a small zit on the butt of the oem elephant. -- Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971
