Have questions or want to discuss cycling? Join Now or Sign In to participate in the BikeRide community.

New: Take part in the January Giveaway for the DYU R1 20" City Electric Bike


Replacing BB
#1
Her I have a shimano BB - UN52 68 BC 1.37 x 24
The frame is threaded. I was just wondering if I have too stick with square taperd or can I upgrade ? Also what are they key numbers in that description for size etc. ?
Thanks
[Image: IMG_0062_zpsurhzcne2.jpg]
[Image: IMG_0060_zpsgruakmoe.jpg]
  Reply
#2
You don't have to stick with square tapered. But whatever you go to has to match your crankset.
The key measurements are basically the width of your BB shell (yours is 68mm) and the length of the spindle. You can measure your existing spindle, but you may need a different length if you change crank sets. Spindle length is mostly determined by the crank, though occasionally you have to make adjustments depending on frame design.

Think a little about what you want to achieve by "upgrading". It can help performance a lot in some cases. But you can also spend a lot of money upgrading BB and cranks without achieving much of anything.
  Reply
#3
(10-12-2015, 01:20 PM)DaveM Wrote:  You don't have to stick with square tapered. But whatever you go to has to match your crankset.
The key measurements are basically the width of your BB shell (yours is 68mm) and the length of the spindle. You can measure your existing spindle, but you may need a different length if you change crank sets. Spindle length is mostly determined by the crank, though occasionally you have to make adjustments depending on frame design.

Think a little about what you want to achieve by "upgrading". It can help performance a lot in some cases. But you can also spend a lot of money upgrading BB and cranks without achieving much of anything.

I think will stick with square tapered as it will just be a commuter. I was also considering changing to single speed at the front and keep original cranks just put single cog on and shorten spindle and 5 speed at rear.
Though if I was too keep the bike for myself I would like to upgrade BB for wheelies Big Grin
  Reply
#4
Why do you want to replace your UN52?  Unless the bearings are rough and gravely, you are not going to have any improvement.

On my PDG, I thought that there was a BB issue - I took it out, inspected it, and put it back in; it turned out that it was not properly torqued.....  It was the original 1992 vintage UN70.  On a bike that had spent a lot of time out side.
Nigel
  Reply
#5
(10-18-2015, 12:07 AM)nfmisso Wrote:  Why do you want to replace your UN52?  Unless the bearings are rough and gravely, you are not going to have any improvement.

On my PDG, I thought that there was a BB issue - I took it out, inspected it, and put it back in; it turned out that it was not properly torqued.....  It was the original 1992 vintage UN70.  On a bike that had spent a lot of time out side.

The bearing are very rough and Im also looking to change the front from 3 speed to 1 speed, so will need to also change spindle.
  Reply


Forum Jump:

[-]
10 Latest Posts
Commute/Beginner Triathlon bikes
Today 12:20 AM
1930s Automoto
Yesterday 02:26 AM
How much do you bike per year?
Yesterday 12:00 AM
Worlds greatest climb road!
01-25-2022 08:10 PM
Urich old tire repair tool
01-25-2022 08:03 PM
Vintage bridgestone
01-24-2022 10:37 PM
First Century
01-23-2022 11:04 PM
Tips on attempting to cold set a damaged...
01-23-2022 06:36 PM
Twin Schwin two speed tandem
01-22-2022 02:44 PM
Help! Trying to identify this bike
01-22-2022 04:02 AM

[-]
Join BikeRide on Strava
Feel free to join if you are on Strava: www.strava.com/clubs/bikeridecom

[-]
Top 5 Posters This Month
no avatar 1. Jesper
34 posts
no avatar 2. ReapThaWhirlwind
18 posts
no avatar 3. jeffg
14 posts
no avatar 4. Jake1
7 posts
no avatar 5. JR Namida
5 posts