nicoth

Hello. The higher end Treks, like the 770, are about 3 lbs lighter than the 560. Does anyone know if this is due to a lighter frame or different components? The brochures vaguely mention reynolds 531 for all their frames, but I've heard that some models used heavier steel for the chain stays.

I've got a complete 560 and a 770 frame and fork. I could transfer the 560 components to the 770, but that wouldn't make sense if the frames are more or less the same. Thanks for any help.

dgodave

I have both an '83 970 and an '83 620.
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But I really dont like the quick/twitchy feel of the 970. It just too racy for me. Do the 560 and 770 differ much in feel/ride/geometry?
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frenchbikefan

dgodave

Thx^. I guess I'm suggesting that there may be other issues to consider besides weight.
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frenchbikefan

look at the picture, you can see that their geometry's are different, that would effect ride and so would the tubing material.

gaucho777 

It's interesting that the rims and tires were not included with the 170, though hubs apparently were included. The 1983 Trek catalog also does not mention rims or tires. Would a customer have wheels built up by the shop (or build him/herself) at the time of purchase?

Picchio Special

Repeat after me: 531 does not = 531, does not = 531, does not = 531. There were - and have pretty much always been - different gauges of 531. Some of the 700 Series Treks were built with 531P - or 531 "Professional" - as per the chart provided by frenchbikefan. That was a very light variant of 531. 501 was generally heavier yet than 531 for the same wall thickness - and the chart provided specs 501 for at least some 560's. When you factor in the weight of the lugs, plus potentially significant weight differences in components and wheels, the weight difference is not difficult to fathom. It's not always useful to equate differences in tubing weight to differences in complete bike weight. That said, the 770 frame is for sure lighter, but not automatically in a way tat will result in a ride you will personally perceive as better, since a few pounds weight difference is rarely a determining factor in that regard. Chances are that the 770 is a better frame built with more care - I'd personally consider it better and make the swap. But as always, YMMV.

Picchio Special

The 170 was a very special animal, and cost a relative proverbial "arm-and-a-leg" at the time. Maybe John Thompson- a member here - can answer your specific questions. The 170's were built on a special gimbaled jig designed by Tim Isaac, and brazed by a small contingent of the Trek team. Some of the early ones have trick lightened Ishiwata fork crowns. They used pressed lugs for the head tube/seat and top tube junctions because of fears of a "can-opener" effect by way of which the cast lugs could potentially punch through the very light tubes. They were - and are - pretty special bikes, and I personally love the way mine rides.

tugrul

My understanding is that all the steel alloys are more or less the same weight, but the 531 alloy has greater tensile strength then 501 and can be drawn thinner, hence lighter tubes.

southpawboston

You are right, and I suspect that's what Picchio Special meant. 531 alloy is 531 alloy, but it was made in different gauge thicknesses, 531P being one of the narrower gauge variants. 531ST was a thicker variant than standard 531, for touring frames. And so on...

Usually the specs for tubesets include the wall diameter, including the butted and non butted sections. Someone somewhere should have that info for the Reynolds 531 variants.

Picchio Special

I'm assuming the butting was different, but I may be wrong about that. In any case, it's probably irrelevant, since they probably weren't sold in similar gauges. Your statement about weight is of course on the mark.
Edit: Interestingly, at one time, published Reynolds materials show 531ST as 8/5 and 501 "Cromolly M" as 9/6, with 501 being the heavier set. A different published chart shows 531ST as 10/7 and 501 as 9/6 again, but without publishing tubeset weights.
Obviously, the lengths of the butted section are going to affect the tubeset weights to some degree, but it also sounds like Reynolds was tinkering with the specs to intentionally position 501 "below" each of its 531 iterations in the pecking order. Maybe the marketing department was the tail wagging the dog at that point. Framebuilders no doubt made their choices based one the specs and not the decals, unless maybe they were offering a wide model range that mimicked Reynolds' own marketing practices.
But it's interesting that in one case the tubing name on the decal changed - 501DB to 501 Cromolly M - while the tybe dimensions remained the same. While in the other instance the decal remained identical - 531ST - while the tubing dimension changed fairly significantly. It's possible the change happened in reverse, as I didn't notice specific dates on the materials, but this less likely unless the engineers temporarily wrested control from the marketing people. It's also possible there's an error in the literature. 531ST would of course have had beefier stays for its intended touring application. But it's almost as if Reynolds couldn't abide having one of its 531 sets appear to be "below" 501 on a chart, based on weight.
Overall, though, this makes the point I have been trying to get at - you can't derive a neat correlation between the decal on the frame and either frame weight or ride quality. It's just not that simple.

Trucker Dan

I think the 170 was $1800 for just the frame and fork in 84. That was quite the sum when you could get an Italian columbus bike complete with record for around $1600. I have been searching for a 170 in my size for years and haven't ever seen one.

Road Fan

Yes, but the steels are about the same density, not the same weight. Density is the weight of a given volume, such as pounds per cubic inch of steel.

Road Fan

Among other places, that info is in the Trek catalogs that are on the Vintage-trek site. It's definitely not a vague discussion.

Road Fan

Specs include the outer diameter and the wall thickness at the butt and belly (middle), eg 7/5/7, 9/7/9, in 10ths of millimeters in this case. Again, it's in the Trek catalogs of the day.

that_guy_zach

Anyone on here have a Columbus tubed Trek?

dgodave

My '83 970 is Colombus SL.
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JohnDThompson 

The early 170s used the reworked Ishiwata SCM crown and Tange Champion pressed lugs:



The later production used Tange investment cast head lugs, Trek cast seat lug, and Tange fork crown.

MetinUz

I have a TX900 with fastback stays.

that_guy_zach

Thanks I was curious how common they are. I have a 970 also but I need to start fighting the stuck seatpost and stem

crazyb

Same length stem on both bikes?

dgodave

Slightly longer stem on the 970.
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But I'm pretty sure that angles and wheelbase are significantly different.
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crazyb

Ya, the longer stem should make it less twitchy.

lotek 

I love my late 1983 built, 1984 decaled 770. I had an 85 670 for a while and it was a nice
riding bike but different than the 770. As far as I'm concerned the 770 (and 760 same frame
different components and color) is one of the more under rated bikes Trek ever built.

I too am almost always on the lookout for a 170 in my size, I think in the time I've been
looking I saw exactly 1 170 on ebay and no it wasn't my size.

Marty

Picchio Special

I got lucky with mine. It had some corrosion, and was not identified as a 170, and has no 170 decal. I spotted the 753 decal. It fits me perfectly and rides great, plus the BIN price was very good.
Apologies for the rambling post this morning - I'm usually a bit better than that after2 cups of coffee. Not way better, but better.