# Replacing Bottom Bracket, Need Advice



## sliebsch (Nov 30, 2012)

I messed up my bottom bracket. Back when I was young and foolish, I may or may not have tried to remove and replace a crank arm using a hammer :madman: I now own a crank arm puller, but my bottom bracket is not really working anymore. I'm looking to replace it, and I need advice on what to get. My bike is a Trek 4500. I would like something stronger than average that can handle a lot of abuse and exposure to the elements. I need advice on sizing, brand names, types of bottom brackets, etc. Even just a link to a good resource would be great. I've done some internet research on my own, but I need some guidance. Thanks!


----------



## Danielrg_usa (Feb 12, 2011)

I am sure you learned your lesson but always use the right tool for the job. As far as size goes you have to get one the fits your BB shell. Your current BB should say how big it is on it or you can always look up the correct size BB for the model year of your 4500. Are you looking to upgrade your cranks too? 

BTW, Sheldon Brown has a lot of good info. Google him and you can find out just about anything you want to know.


----------



## Danielrg_usa (Feb 12, 2011)

Sheldon Brown's Bicycle Glossary Bo--Bz

Here is the link to the BB section on the Sheldon page


----------



## TiGeo (Jul 31, 2008)

If you don't have the knowledge, I strongly suggest going to a shop for this. So many types and configs/sizes it is east to mess this up. They can be very challenging to remove.


----------



## sliebsch (Nov 30, 2012)

I'd like to do it myself, learn how to repair my own bike. If I can't follow an online tutorial then I will get a shop to do it, or try again. I'm not worried about screwing something up while I'm learning, it's not like I'm defusing a bomb here. Haha. Just looking for impartial advice on types and brand names. I want to pick out the part myself regardless of whether or not I'm having someone else install it.


----------



## dru (Sep 4, 2006)

If you insist on DIY, you need to find out what type of BB you have. You also need to find out your shell width. Lastly (again depending on type) you need to find out your spindle length.

That's pretty impartial.

Once you can answer the above questions, then come ask for good brands, etc.


----------



## sliebsch (Nov 30, 2012)

It's the BB that comes standard with the bike(Trek 4500), so it's a square taper, 73mm width, 113mm spindle length. I wasn't taking a shot at you at all with the "impartial" comment, I just think if I went to a bike shop as opposed to a forum, they might take advantage of my noob status and try to push a product on me that isn't what I actually want. I'm asking for good brands because I'm sure there are many different brands that manufacture BBs that will fit on my bike. I'm also asking about different types, because I got the impression that there are different configurations that are waterproof, more durable, etc.


----------



## Danielrg_usa (Feb 12, 2011)

If you are mechanically incline and have the proper tools BB removal and replacement is cake. Watch a few YouTube videos to familiarize yourself with how it is done before you tackle it. I am all about doing it myself if I can and that is what I did. Of course I did research what size and type of BB I have first! Good luck! 

Sent using my fat thumbs!


----------



## pilotman520 (Mar 28, 2011)

Well the bad news is that there really aren't any "good" square taper bottom brackets being made any more. To get the newest style external bottom bracket would require buying new cranks as well. If you are interested in that route you can usually get a shimano LX crankset with BB for less than 100 bucks on ebay. And if you do that you will never need a crank puller again.


----------



## goodmojo (Sep 12, 2011)

I just went through something similar. I have an old bike with square taper and just bought a new frame. Compatible square tapers are shimano UN 52 or UN 55 and require a couple of tools like the crank puller. They come in either 68 or 73mm widths and a variety of crank shaft lengths. They cost about $30-$40. 

The old bottom bracket wouldnt work on the new bike. so I was planning to go this route but the bike shop wanted $100 and they didnt have the parts so would have to order and wait a week. I went to craigslist and got an slx crank with bottom bracket for $60 and it installed very easily onto the new frame. The new bottom bracket will fit both 68 or 73mm widths via shims that go between the external cups and the bottom bracket. The bottom bracket just screws in by hand then you can use a BB tool to tighten it up.


----------



## dru (Sep 4, 2006)

sliebsch said:


> It's the BB that comes standard with the bike(Trek 4500), so it's a square taper, 73mm width, 113mm spindle length.


Get a UN52 or better Shimano BB off ebay or some place like that if the LBS can't get you one.

Otherwise, pay big bucks for a Phil's or in my case a stainless roller SKF which was just over 100 or so. Other than these two and maybe another brand or so, no one is making really good square taper BB's any more.

The BB swap isn't hard to do at all, but you need the install tool if you haven't got one already. Good luck!

Drew


----------



## TiGeo (Jul 31, 2008)

In terms of ST BBs, its fairly straightforward as long you know the spindle length and BB width. A Shimano UN-54 should be $25 and is decent quality. I bought one a while back on eBay for my SS. Get the Park BB tool that fits into your ratchet. I suggest passing a QR thought tool and BB so that the tool is held in place; you often have to use a breaker bar to get old BBs out. Make sure you know which way each side is threaded...I will repeat this...make sure you know which way each side is threaded. Once out, clean out the BB shell, great the @#$#@$ out of it, and reinstall. Don't use grease on the tapers, they should be dry. Clean the inside of the crank arms where they slide on the spindle...again...dry and clean will prevent noises. A shop should have you out the door for $50. In terms of different brands etc, there aren't many out there and honestly, the Shimano UN BBs are bullet proof...no need for anything fancy; there is ZERO performance increase by spending a bunch of money.


----------



## p08757 (Mar 15, 2012)

Danielrg_usa said:


> Sheldon Brown's Bicycle Glossary Bo--Bz
> 
> Here is the link to the BB section on the Sheldon page


Thanks! +1 Rep. :thumbsup: I was looking for something to tell me what type of BB I had so I knew what type of tools I would need to remove it.


----------



## Danielrg_usa (Feb 12, 2011)

p08757 said:


> Thanks! +1 Rep. :thumbsup: I was looking for something to tell me what type of BB I had so I knew what type of tools I would need to remove it.


No problem. Being a newbie that loves to wrench and do my own work I have used the Mr. Brown's info a lot. Ask a lot of stupid questions, read Sheldon Brown, and watch youtube and you can work on any part of your bike yourself. Provided you can affoard the specialty tools needed lol.


----------



## hey_poolboy (Jul 16, 2012)

I replaced my first BB this past summer. The part I found most difficult? Finding a local place to buy the tool to remove the old BB. 

It really isn't difficult if your slightly mechanically inclined. I had the old one out and cleaned everything and new one installed w/i 45 minutes. Like others have said make sure you know which side is which. My new BB was labeled for drive side, and direction of rotation for installing each side. Couldn't really go wrong.


----------

