Which 900 are you looking at, or more generally what steel tubing are you looking at for all the bikes? Trek used different steel on different versions throughout the 80's and 90's. But for any of these, you need to look at the actual tubing because reynolds, true temper, tange, columbus, all had a bunch of tubing available during the time.

Generally the best and lightest tubing was the higher end heat treated stuff: OX Platinum, 853, Columbus Foco.

After that would be heat treated versions other than the above.

Then the more common but still very good quality 4130 steels: Tange prestige, OX, OX2, OX3, etc.

Then your big box store and low end unnamed steel bikes. Sometimes these are labeled as cromo, or high tensile, or just steel. If the model doesn't specify a specific tubing, I'd assume the worst.

Probably subjective as to the joining methods. Well made fillet brazed is the most desirable IMO, lugged next, tig last, key being all have to be done by someone with a ton of skill, but all of these higher end steel frames are pretty good quality. There's probably someone else that is more qualified at comparing these but this has been my general outlook on older steel frames.

 

I'm looking at more specific 930, 950, 970 from the late 80s with lugged frames. I believe they should be double butted True Temper OX types. Also, didn't they make fillet brazed lugged frames, and weren't the old Schwinn Paramount Tange tubing fillet brazed?

My main interest is around nicely assembled lugged steel mtb frames, so thanks for the tube type rankings given above.

 

I believe trek stopped using lugs on steel mtbs in the mid 80's, then brought the lugs back in '89 with the Singletrack series. However, they didn't start using true temper steel until 1990. True temper, lugged treks were only made from 1990 to 1994.

As for the type of true temper, that varies a little on each model. The 990 the 970 usually used higher end steel TT steel than the 950 and below. Also, the 990 and some years the 970 were usually heat treated while the 950 and below were double butted.

So depending on the year, different models use different types of true temper steel. For example, I have a '90 930 that is made with a True Temper AT ATB double butted Chro-moly main frame and TT tapered Chro-moly stays. The 930, 950 and 970 for '90 were all made the same TT steel, but the 990 that year had a TT ATX heat treated ATB Cro-moly main frame with the same stays. I also have a 1991 trek 970. Same TT steel as the 990, but double butted while the 990 is heat treated. But, unlike in 1990, the 950 and 930 used different TT steel than the 970.

Also, in 1989 and 1990 trek used smaller diameter tubes than 1991 thru 1994.

Another thing to consider is the fork. Trek used different forks on different models. The higher end models, for the most part, used larger diameter tange steel forks than the lower models. Some years the lower end models used non-tange steel as well.

There is a huge difference in the ride between my '90 930 and '91 970. But I think it has more to do with the frame and fork tubing diameters than type of steel. The 970 is much stiffer and more responsive with the larger diameter frame and fork tubbing, while the 930 is much more complaint and forgiving.

I also have an '88 Bridgestone MB1 and it is even more compliant than the 930. It is one of the most comfortable MTBs I have ever been on. Fast and smooth when your cruisn

As for Schwinn mtbs... :yawn:

 

Nice detailed info, singletrackmack, you know these Treks!! And nice collection :thumbsup: Aside from tube types and heat-treated vs non- versions, and since my interest is with the lugged construction, do you know if these were filet brazed or put together by other types of welding, gluing?

 

I am pretty sure lugged frames and fillet brazed frames are both brazed and tig is obviously welded. Fillet and lugs are two different ways to use brazing to join tubes. The tubes on the treks are all joined by burly and clean looking lugs