Mountain Bike Reviews Forum banner

1 - 15 of 15 Posts

·
No known cure
Joined
·
4,258 Posts
Discussion Starter · #1 ·
I have a pile of parts looking for a mid 90's 18-19 inch steel frame but I need a longish top tube. I'm kind of a knuckle dragger and my last two custom frames have 24 inch top tubes. Anything I should be specificaly searching for? I think a 23.5 inch TT with a 100mm stem would work. It doesn't have to be anything exotic, but should have nice tubing. Thanks
 

·
Stokeless Asshat
Joined
·
3,360 Posts
I've heard of an Otis Guy with a reeeeeaaaaly long TT.
 

·
Neo-Retro Forever
Joined
·
1,576 Posts
Why not run a 23 inch top tube with a 125mm stem? The handling of early-mid 90's bikes are based on longer stems anyhow...
 

·
Registered
Joined
·
1,470 Posts
Iron Horse. The MT700 A-frames were lonnnnng.
 

·
Registered
Joined
·
5,985 Posts
On a bike with a sloping top tube, buy the next larger frame size and the TT is longer.

I'm not sure that any 1990's frame was intended to be run with a 100mm stem. With TTs the length that you're interested in 120-150mm was the norm at the time for stem length.

Also, pay attention to seat tube angle. A 23" top tube a frame with a 74 degree STA is a longer bike than a 23" top tube on a frame with a 72 degree STA.
 

·
Registered
Joined
·
1,424 Posts
Also, pay attention to seat tube angle. A 23" top tube a frame with a 74 degree STA is a longer bike than a 23" top tube on a frame with a 72 degree STA.
That seems counter to what I would of thought. Would not a 74 degree STA be more vertical bringing the seat closer not farther to the stem?
 

·
Registered
Joined
·
5,985 Posts
That seems counter to what I would of thought. Would not a 74 degree STA be more vertical bringing the seat closer not farther to the stem?
The saddle should be in the same position relative to the bottom bracket regardless of seat tube angle. So with a steeper STA the saddle needs to be moved backwards relative to the seat tube by either having the saddle slid backwards on it's rails or by using a seat post with more offset. The steeper your STA, the further rearward the saddle must be moved to maintain your position on the bike.

Slacker seat tube angles put more of the top tube length under the saddle instead of in front of the saddle.
 

·
No known cure
Joined
·
4,258 Posts
Discussion Starter · #14 ·
The saddle should be in the same position relative to the bottom bracket regardless of seat tube angle. So with a steeper STA the saddle needs to be moved backwards relative to the seat tube by either having the saddle slid backwards on it's rails or by using a seat post with more offset. The steeper your STA, the further rearward the saddle must be moved to maintain your position on the bike.

Slacker seat tube angles put more of the top tube length under the saddle instead of in front of the saddle.
I had a Ventana full sus built last year with a 74* STA and a 24"TT. with a 70mm stem. The other frame has a 72* STA and 24" TT with a 50mm stem. Both are perfect.

Thanks for all the input. I know there are long TT production frames out there, like the first double diamond Alpinestars CR frames. My 1994 had a 23.4 TT and OX 3 tubing.

I'm trying to stay away from anything desirable and sought after due to costs, and because it will be a winter beater. I'll probably end up running a longer stem and keep an eye out for a sloping TT Rocky, Voodoo or something similar.
 

·
Registered
Joined
·
72 Posts
A 1991 20" Kona Explosif had a 24" effective top tube, according to the catalogue. I know 20" isn't 18 or 19", but the sloping top tube might still give you enough stand over. Just my 0.02 $
 
1 - 15 of 15 Posts
Top