Author Topic: BSA bottom bracket backwards?  (Read 1574 times)

bangacan

BSA bottom bracket backwards?
« on: April 30, 2024, 06:01:11 AM »
I got a new gravel frame from TanTan cycling. Beautiful frame but having issues with the bottom bracket. I fear they glued the threaded inserts in backwards. Instead of tightening towards the rear of the frame they tighten towards the front. I saw this same issue somewhere on a different forum and the person was told to use green loctate on the bb threads. I don't understand the physics involved with why the bb could/would looses but I am very disappointed as I got a BSA frame because I was nervous about a pressed in BB in a Chinese frame.

Another oddity is that my TRP BB says to use two spacers drive side and one non-drive in a 68mm shell. My digital caliper measures 68mm. When I used the 3 spacers the crank bottomed out against the bb and wouldn't turn. I had to use 1 spacer drive side and none non-drive, as if it was a 73mm shell. Easton ea70 cinch crank.

thoughts?



sync1

Re: BSA bottom bracket backwards?
« Reply #1 on: April 30, 2024, 07:23:39 AM »
Your BB instructions are for MTB splindles.
Cant find you crank specs but I assume it have a road spindle (shorter than mtb). So, you should use 1 spacer.

bangacan

Re: BSA bottom bracket backwards?
« Reply #2 on: April 30, 2024, 04:48:17 PM »
https://cdn.shopify.com/s/files/1/0840/7783/8623/files/Bottom_Bracket_Installation_-_BSA.pdf?v=1705436718

What you say makes sense as far as how I had to do it but my caliper read 68mm.

I'm wondering if there is any reason why I can't take the left bb cups and put them on the right side? Same for right side cup. If the threaded inserts are indeed on the wrong side then the threading should work. no?

frnchy

Re: BSA bottom bracket backwards?
« Reply #3 on: April 30, 2024, 10:11:41 PM »
I'm wondering if there is any reason why I can't take the left bb cups and put them on the right side? Same for right side cup. If the threaded inserts are indeed on the wrong side then the threading should work. no?

Should work as long as you're using a crankset standard with identical bearing sizes left and right- it's basically like taking the bottom bracket assembly as a whole and rotating it 180 degrees. But I would sooner raise a warranty claim - if QC didn't catch such an egregious error, what else might they have missed?

maui400

Re: BSA bottom bracket backwards?
« Reply #4 on: May 01, 2024, 03:13:47 AM »

bangacan

Re: BSA bottom bracket backwards?
« Reply #5 on: May 01, 2024, 05:36:58 AM »
Should work as long as you're using a crankset standard with identical bearing sizes left and right- it's basically like taking the bottom bracket assembly as a whole and rotating it 180 degrees. But I would sooner raise a warranty claim - if QC didn't catch such an egregious error, what else might they have missed?
Yeah, I might contact them. They will ask me to have that verified by a shop which is fine. I might just put an id mark on the shell and see if it starts to move.

The shifting is also not great. I probably should have stuck with sram or Shimano but I bought a Sensah 1x11 shifter/rear der with hydraulic brakes. The brakes are AWESOME but are the shifting woes the Sensah group or a chain line issue? Hard to decipher. I’m trying to become a better mechanic, I’m a building contractor damn it I should be good at this, but I’m getting some shifting advice soon from a mechanic friend

TidyDinosaur

Re: BSA bottom bracket backwards?
« Reply #6 on: May 01, 2024, 09:57:50 AM »
My first build was with a Sensah SRX pro 1x11 group. It took me A LOT of time to get it shifting ok-ish and it never was good. I have since then switched to GRX and Ultegra and have non of those problems.
SO yes, chance are it is the groupset