Bicycle Mechanics - figuring out specifications

I am interested in overhauling the hubs and checking the bottom bracket on my MTB (ca. 95 Giant Sedona - with a real MTB frame and full STX components, not the recent comfort MTB style). It's only been ridden much in the past 18 months, but is a commuter bike, so I know it needs work.

The problem is figuring out what bearings and bottom bracket should be used as replacement. One of the LBS's in town told me just to remove the old parts, bring them down, and match them, since they didn't have a database that would provide that information, nor did they know of one. I would much rather finish the maintenance in one go than remove the parts, go downtown, match them, and return.

I had assumed there must be some central source of information - is there?

I am interested in overhauling the hubs and checking the bottom bracket on my MTB (ca. 95 Giant Sedona - with a real MTB frame and full STX components, not the recent comfort MTB style). It's only been ridden much in the past 18 months, but is a commuter bike, so I know it needs work.

The problem is figuring out what bearings and bottom bracket should be used as replacement. One of the LBS's in town told me just to remove the old parts, bring them down, and match them, since they didn't have a database that would provide that information, nor did they know of one. I would much rather finish the maintenance in one go than remove the parts, go downtown, match them, and return.

I had assumed there must be some central source of information - is there? No one source of info for everything. Too much stuff and too manny combinations and possibilities thru time.You are gonna have to measure your BB shell width and spindle length. If I don't know what size bearings are in something I measure them too. A caliper is good to have.

The best thing to do is to call a shop in your area that is a GIANT dealer. They may have some specifications on file.

But in general, NO, there is no database with this information. You can try sending Giant an e-mail asking them what to use. It'll either be a 72 or a 68 housing width and generall a 110 to 115 spindle length.

The easiest thing to do is to remove your and usually on a sticker or stamped into the housing is a number (or set of numbers) something like 68x112.

The best thing to do is to call a shop in your area that is a GIANT dealer. They may have some specifications on file.

But in general, NO, there is no database with this information. You can try sending Giant an e-mail asking them what to use. It'll either be a 72 or a 68 housing width and generall a 110 to 115 spindle length.

The easiest thing to do is to remove your and usually on a sticker or stamped into the housing is a number (or set of numbers) something like 68x112.Actually, it's 73mm, and if there is a designation like 68x112 on the cartridge, it will be on the body and has to be removed to be seen. What can be seen will be the threading. Easy enough to measure the shell width and spindle length rather than guess.

I am interested in overhauling the hubs and checking the bottom bracket on my MTB (ca. 95 Giant Sedona - with a real MTB frame and full STX components, not the recent comfort MTB style). It's only been ridden much in the past 18 months, but is a commuter bike, so I know it needs work.

The problem is figuring out what bearings and bottom bracket should be used as replacement. One of the LBS's in town told me just to remove the old parts, bring them down, and match them, since they didn't have a database that would provide that information, nor did they know of one. I would much rather finish the maintenance in one go than remove the parts, go downtown, match them, and return.

I had assumed there must be some central source of information - is there?

The wheel bearings are perfectly normal. The rear will use 9 1/4" balls on each side, and the front will use 10 3/16" on each side. See: http://sheldonbrown.com/harris/hub-parts.html#bearings. See my article on overhauling hubs http://sheldonbrown.com/cones (http://sheldonbrown.com/cones)

As to the bottom bracket, it will be a cartridge unit, no maintenance possible or needed. If the bottom bracket is giving you trouble, you just need to buy a new cartridge bb for about $30. If it isn't giving you trouble, leave it alone.

For sizing information, see my Bottom Bracket Sizing page: http://sheldonbrown.com/bbsize (http://sheldonbrown.com/bbsize). Your local shop should have a suitable bottom bracket, or you can order one from us http://harriscyclery.com/bottombrackets

Sheldon "If It Ain't Broke..." Brown

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| There are several good protections against temptation, |
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Thanks for the very helpful information, everybody. I'm making up a shopping list...

Thanks for the very helpful information, everybody. I'm making up a shopping list...

Good, there is nothing worse than getting home from the bike shop with a bagload of goodies and ready to get into it, only to discover (a) you've left the most important part off the list and you can't do a damned thing until tomorrow or (b) you need a SPECIAL tool to undo some part of the bike, and you can't do a damned thing until tomorrow.

You shopping list does include the required tools? Things like BB removal tool, cluster lock-ring removal tool and chainwhip; cone spanner (at least one); and headset spanner?