1997 GT RTS All Terra Mountain Bike Advice on Bearings and Handlebars/Accessories Due to Hand Pain

[bikeworkshop]

It won't wobble when it's pinched down by the collar, but it will slowly fatigue the frame at the toptube weld or the bottom of the slot, causing failure like this:
Might take years. Might not!

 

[TheJay]

The post is 26.6mm and looking at the way it interacts with the frame, that has to be the correct size. So I need a 26.6mm rigid seat post that is 270mm long or less.

 

[bikeworkshop]

26.6 is a little unusual.

Iirc 26.8 was a common gt post size, and some RTSs are deffo 26.8.

But if a 26.8 won't fit, and the clamp slot is parallel, then maybe not in this case.

 

[TheJay]

The post actually says 26.6mm on it and I ran the callipers around the inside of the mount and got the same measurement even after moving the post around inside and putting pressure on the sides.

 

[bikeworkshop]

Great.
We check by offering the next size up post, but you'd only have that option in an old school bike shop.

I'm going to ask the RTS community

 

[bikeworkshop]

Here's a voice of authority:

Either 26.8 or 27.0 depending on Taiwan or USA built frame .

 

[TheJay]

Thank you, so I suspect it must be 26.8 in that case as 26.6 is pretty snug. Is there any way to determine if Taiwan or USA built frame or given the fact it's had a 26.6mm seat post fitted most of its life we go with 26.8?

 

[bikeworkshop]

The frame number will tell you US or Taiwan- you might need to do some googling, or post the number on here and ask the question.

It's not a big cost to buy a 26.8 used on ebay - that's the most likely size - you could buy ot borrow a 27.0 too!

The top bit of the seat tube will be a little distorted If is had the wrong size in there a few years.
A proper bike shop would be the best bet, because they would know how to check it, and repair if necessary.

It's incredibly common for 90s frames to end up with the wrong size post, tricky to sort.

 

[bikeworkshop]

I've had many and all have been 26.8. I have a few posts in that size in my stash if you are looking for one.

Post in thread 'GT RTS seatpost size'

Wednesday at 22:10

I've had many and all have been 26.8. I have a few posts in that size in my stash if you are looking for one.

• ishaw

 

[kingoffootball]

Thank you, so I suspect it must be 26.8 in that case as 26.6 is pretty snug. Is there any way to determine if Taiwan or USA built frame or given the fact it's had a 26.6mm seat post fitted most of its life we go with 26.8?

If it is a Taiwan-made frame the serial number will start with an H, as they were made at the Hodaka factory. I think any US made ones might be numerical only, but I only recently started adding aluminium numbers to my spreadsheet, so I don't have any US RTS numbers recorded yet.