Jump to content

Bottom bracket replacement


NickGM
 Share

Recommended Posts

I'm looking to replace the bottom bracket of an old mongoose mtb. OK well technically my old man is replacing it for a youngster in his dorpie, and he's asked me to find out what part he needs.

The BB in question is a Shimano BB-LP28, 68, BC1.37x24, 110mm square taper spindle. I've done a bit of reading and it looks like the LP28 was just a model number and the modern day equivalent is the UN series of shimano BBs. Something like this:

https://www.chainreactioncycles.com/shimano-un26-square-taper-bottom-bracket/rp-prod34652

except, the spindle is 113mm in the above example. 

Does anybody know where I can find a local replacement?

Link to comment
Share on other sites

I have actually just noticed this add (below), which could work. It's like-for-like with the exception of the 113mm spindle.

https://bikehub.co.za/classifieds/item/bottom-brackets/486207/square-tapered-bottom-bracket

I'd imagine the only real issue is that it will move the cranks 1.5mm out and affect the chainline a bit. Not sure how much trouble that will cause. 

Link to comment
Share on other sites

9 minutes ago, DieselnDust said:

The old MTB's have a 73mm bb width so a 73mm and not a 68mm bb is needed.

This bike definitely needs a 68mm BB, so maybe not as old as I made it sound. 

Link to comment
Share on other sites

call Nill's at Woodstock cycle works, or someone there. Use short concise sentences, if you go there maintain eye contact and dont let him wander ahaha. He most probably will have something. he's arguably bit of a mission to deal with sometimes (or i'm just too impatient haha), but he is very knowledgable about the older stuff. 

Link to comment
Share on other sites

2 hours ago, NickGM said:

I'm looking to replace the bottom bracket of an old mongoose mtb. OK well technically my old man is replacing it for a youngster in his dorpie, and he's asked me to find out what part he needs.

The BB in question is a Shimano BB-LP28, 68, BC1.37x24, 110mm square taper spindle. I've done a bit of reading and it looks like the LP28 was just a model number and the modern day equivalent is the UN series of shimano BBs. Something like this:

https://www.chainreactioncycles.com/shimano-un26-square-taper-bottom-bracket/rp-prod34652

except, the spindle is 113mm in the above example. 

Does anybody know where I can find a local replacement?

I have exactly what you're looking for. The code on the barrel says: BB7420 - BC1.37 x 24T L - 68 - R. Then on the one spindles it says: B110.5

20210805_132327.jpg

Link to comment
Share on other sites

34 minutes ago, RobertWhitehead said:

I have exactly what you're looking for. The code on the barrel says: BB7420 - BC1.37 x 24T L - 68 - R. Then on the one spindles it says: B110.5

20210805_132327.jpg

Thanks robert! Will message you.

Link to comment
Share on other sites

40 minutes ago, DieselnDust said:

https://bike.shimano.com/en-EU/product/component/tourney-a070/BB-UN26.html

 

looks like the BB you're replacing is for a double chainring crankset

 

For interest sake what model Mongoose is this for as I'm not aware of a Mongoose MTB that came out with a double chainring crankset

It's a 3x9. I'll try get a pic. I think I've sourced a BB for it though. 

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

My Profile My Forum Content My Followed Content Forum Settings Ad Messages My Ads My Favourites My Saved Alerts My Pay Deals Settings Help Logout