HooKooDooKu

I've got a Diamond Back Sorrento circa 1995 that needs a bottom bracket replaced.

So I bought a Bottom Bracket Tool, and a Crank Set Puller, and I've managed to remove the bottom bracket. But how do I determine what bottom bracket to order to replace it with?

BikePedia doesn't list any information on my Bottom Bracket: https://www.bikepedia.com/quickbike/B...o#.UfIN1E0o4dU
I can't find a part number on the bottom bracket itself (should I be able to find one? Where?)

jimc101

The BB required is determined by the crank you are going to use.

For a 1995 Diamond Back Sorrento; if keeping the original crank, you need to measure the BB shell (68mm or 73mm), and spindle length on the BB you have removed, this info should also be stamped on the BB you removed. It will be square taper, English thread.

cny-bikeman

You only need to replace the entire bottom bracket if both spindle and cups are damaged. Otherwise the spindle is enough. A bike shop will be able to tell you what is needed or Google bottom bracket Sheldon.

jimc101

This is only the case if it doesn't have a sealed cartridge BB, having recently pulled a BB from a 1995 Assent (only a few models up from the Sorrento), this had a LP26 BB, with the info supplied by the OP, and how they have described it, would be surprised if it was anything other than a sealed unit.

Bill Kapaun

Look for a number inside the crank arm in the format.....FC-Mxxxx

HooKooDooKu

1. Where should I find the information stamped on the BB.
2. When you say "measure the BB shell", exactly what are we talking about:
A) The size of the BB Tub on the bike?
B) The distance from outside edges of the fixed flange/removeable ring?
C) The distance between the insides of the fixed flange/removeable ring?
D) Other ?
3. I assume spindle length is the width of the entire BB (tip of square taper to tip of square taper) - correct?
4. Prior to the need to replace the BB, I had considered replacing the cranks because I've desired some larger chain rings. What are all the pit-falls I need to watch out for in attempting such an upgrade on my own?
A) I know I'll likely need to replace the chain with a longer one to account for a larger chain ring.
B) I know I'll need to adjust the height of the front derailleur to account for the height of the largest chain ring. I've also come across suggestions that the derailleur might need to be replaced. It that likely to be necessary?
C) What else might I not know about trying this type of change out?

Additionally, I'll like to hear some input on what are some dependable places to order bicycle parts. The only place I've ordered cycle related stuff has been cloths and general gear from sporting good stores and online at Performance Bike. But Performance seems to only carry a limited amount of higer end components. As you can see from the original build at bikepedia, the original parts were Shimano AceraX level.

jimc101

If any sizing info is stamped on the BB, this will be physically on the center of the Bottom Bracket you have removed from the bike, it may have been on a printed label which is no longer there.

The BB shell is part of the bike, see here for info https://en.wikipedia.org/wiki/Bottom_bracket being an MTB, BB shells are either 68mm or 73mm


Yes

How large a outer are you looking at going to, if a 48T, you will need a new chain, and will need to raise the FD, although you probably won't need a new FD.

Acera is still around, it's at the low end of the Shimano MTB range, and is 8 speed as opposed to 7 which your 1995 bike had. Would look at the cost of replacing any parts on the bike vs a complete new bike, you may run into compatibility issues, and any replacement of multiple low end parts will soon add up to the cost of a complete replacement bike. Where to get parts, LBS, google etc

Bill Kapaun

IF you keep the same crank, refer to my last post regarding the model.
Shimano has tech docs online and one can often refer to them for the proper BB.

IF you change the crank, you use the BB required by that crank.

Are you sure you want larger rings? A 48T large ring would pretty much make your 11T cog useless. OTOH, you would probably spend most your time in the middle ring which would make your largest cog less useful except on hills.

HooKooDooKu

I have a "real" mountain bike, so this bike for years has been used as a road bike. As such, I've considered changing the chain rings to something closer to a road bike as the current smallest cog never really gets used. But as a look at the number of parts that might need changing, I get the feeling I'm only going to be replacing only the BB.

Bill Kapaun

If the current smallest cog seldom gets used, adding 6T to the large ring would mean you'll have twice as many smaller cogs that seldom get used.

sreten

Hi,

I assume the smallest chainring doesn't get used much was meant.

42 with 11 is as tall as the highest 52 with 14 on my road bike.
IMO there is little need for bigger front chain rings.

A 12 to 21 cassette, (12, 13, 14, 15, 17, 19, 21) compared to
the 11 to 28 (11, 13, 15, 18, 21, 24, 28) fitted, is much more
suitable for a road bike, and will make the small chainring useful.

rgds, sreten.

HooKooDooKu

After buying two tools (BB tool and Crank Set Remover tool) got the BB to the LBS and simply bought only a replacement BB for now. The new BB is in place, it fits perfectly (didn't have to tweek the front derailleur at all) and now I know how to replace the BB and can change out the Chain rings sometime in the future.

Thanks to all those that help (both online and at LBS).