Fixing the Bottom Bracket Threads on a Retro Giant ATX770

The bottom bracket threads on this Giant ATX770 vintage mountain bike were damaged during the removal of the bottom bracket, we were able to fix them with tap.
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[@aaronbehindbars]

That is a really cool frame and fork! I have been gaining a greater appreciation for Giant's designs. I have a Cadex CFM1 which has some really lovely aluminum lugs and cool finish on the carbon tubes. It has earned a spot on the wall in my house.

[@Ableurself]

Do you still have this frame for sale for what height person id it for!? Thanks

[@GringineerCycles]

Yes we do still have the 15.5” ATX770 in stock, it would work best for someone 5’2”-5’7” or so. www.gringineer.com/155-giant-atx-770-frameset.html

[@cecilecorpuz5735]

It's best to install the handles with taps installed this way you'll keep everything lined up the rotate each handle a little bit at a time until everything starts to run smoother, but for me I'll be using a lot more cutting oil. For really bad un-saveable BBs I'll then go a next step further tapping out then rethreading to ITALIAN Thread of which I have done so several times before. One other Bicycle Mechanic saw what I was about to do and he said, you're not doing what I think you are doing, I replied, yea I am, he then said I don't know any other bike wrench who would do what you are about to do, of course you'll need the correct tooling and the know how to perform this work.

[@Gledii]

what if the problem is right in the begining of the thread and you cant even start by hand? thanks

[@madtownangler]

The first bike I worked on I tried putting the bottom bracket in the wrong side Had to ride the bus to the bike shop and have them retap the threads. Trying to use a British book before the Internet was around now you can just watch a KZbin video and learn stuff.

[@nguyentrungcnn]

Amateur question! Few days ago I took off the BB and saw some threads were broken. I guess other threads would be gone in near future. I wonder if the shell inside diameter changes after we use the tool in video? Will my current BB still fit well?

[@GringineerCycles]

Great question. The cutting dies are the same size as the as the bottom bracket so they will not enlarge the bb shell diameter but if the shell is damaged enough ( many threads missing or if it has been wallowed out the taps will not fix the issue as the shell is no longer round or not enough metal is left to retap.) When this happens there are still a few solutions sunlite makes a square taper bb that works with out threads which I have used before. If the bottom bracket screws in but gets loose quickly threadlocker could be applied. Hope this helps. Joel

[@nguyentrungcnn]

Thank you!

[@flangle]

Awesome vid. I wanted to ask what bottom bracket type these old Giant's have? I renovated a Giant Chicago and installed a JIS compatible crank set but after a year the left crank arm constantly keeps loosening. Is it actually an IOS square taper?

[@GringineerCycles]

As an Asian bike brand I would assume most if not all Giants are JIS but it would depend on the parts kit of the bike, if the crank you removed was ISO then that could be the problem, also the new crank if used may have been wallowed out already or unfortunately it may not have been tightened enough when installed so now it is wallowed out and doesn't stay tight.