Road Fan

I've seen specs for 531 C tubing, both from Trek (1983 catalog in Vintage Trek) and from Reynolds (one of the Reynolds charts shown at Equus bike). They do not happen to match.

There's also a Reynolds chart of decals (at Equus) that shows 531 CS was "531 Club Sport." But I didn't see any specifications for 531 CS, in terms of butt/belly/butt thicknesses (i.e. 9/6/9). Has anybody seen such information, the tubing gauge line-up for 531 CS?

The 1984 (at least) 6xx frames used it.

The Golden Boy 

I haven't seen any specs on 531CS. It's a relatively rare tubeset- the only hard info I've seen is the decal chart off the Equus site. It looks like Trek was the main user of that set, and there were a few smaller companies as well- but Trek was the big user.

The 600 series bikes would have used 531CS or a variation of anything with a double butted 531 main frame and CrMo stays and fork- the earlier 600 series bikes would have used a fork and stays of Manganese alloy or other CrMo- not just Reynolds.

Pemetic2006

Just looked at my 1982 614. It says "butted" over "531" but doesn't say "double" or "CS" anywhere.

Ex Pres 

EDIT: see T-Mar's below

You have to think of 531CS as a "tubeset", not just a tubing designation.

As far as the 531C, the C came about when Reynolds morphed their designations from (their basic) 531 and (the lightweight) 531SL into 531C (Competition) and 531P (Professional). The tubes didn't change, just the marketing.

Ex Pres 

In '82, I think the fork and stays were Ishiwata, but I'd have to check the catalog. IIRC my '83 is Tange f&s.

Pemetic2006

Yep. The dreaded death fork!

T-Mar

Reynolds 531 Club Sport:
Top & Down Tube: 0.8/0.5/0.8
Seat Tube: 1.0/0.7
Seat stays, chain stays: 0.9
Fork blades: 0.9 (i.e. not taper thickness)
Tubeset weight: 2250g
Use: touring, commuting, beginner racer, all rider weights, all rider experience levels

Bruce27

I had a poll going to try and find out how big a problem this fork really is. Last I recall, 8 people didn't have an issue, 1 did.
My search skills must be lacking as....for the life of me, I cannot locate that thread/poll.

The Golden Boy 

Your sticker should say something to the effect of 'guaranteed built with butted Reynolds 531 frame tubes.'

It says the main frame is 531, the tubes are butted, and it doesn't say anything about the fork or stays.

The Golden Boy 

In the other 531 thread, I noted that my 1978 730 is 531/531. It's a great bike- it's lightweight and consequently I would consider it "flexy." While there are some people that would consider the 531C 720 "flexy," I would associate the weight and the ride of the 720 closer to that of my 1985 620 than I would the 730.

Is that clear?

730- 531= flexy

720- 531c= not so flexy

620- 531cs= not so flexy


The way I understand it, if the 720 was made of tubing of the same properties and thickness of the same tubes as the 730- it would be more flexy than the 730, as it has an almost 6cm chainstay length and almost 8cm longer wheelbase. But it's not.

rando_couche

I replaced my '84 610 (531CS) with an '83 700 (full 531 db). Virtually identical geometry, but the 700 feels much more responsive (lively/springy/flexy), so I'd put good odds on the tube set in my 610 (25.5"/65cm) being heavier than that spec. All of the components on the 610 moved over to the 700, so it's not different wheels/tires/etc.

Several folks who should know have claimed that Trek's 531CS had a heavy gauge (1.0/.7/1.0) downtube. That's consistent with the way my 610 rides. Also, I recall an authoritative source (Reynolds?) saying that 531CS was 531 main tubes and 501 (seamed 4130) everywhere else.

SP
OC, OR

Pemetic2006

That is what it says.

Pemetic2006

Mine seems fine but I haven't ridden it much. I assume it is the original, 34 year old fork.

bikemig 

That's what is says on the vintage Trek website, "Reynolds 531CS (Club Sport) frame tubing is first used by Trek. According to Terry at Reynolds-Cycle.com: "531CS was a special set, supplied mainly to Trek. The main triangle was butted 531 and the rear stays were CrMo (501)." The fork was taper gauge CrMo (501). (Info. provided by Dickey Greer.)"

https://www.vintage-trek.com/Trek_timeline.htm

My 1984 Trek 610 is, I think, a fine long distance machine. It is not the lightest bike I own but it is comfortable eating up the miles. I just picked up a 1978 Trek TX 900; we'll see how they compare. The TX 900 will undoubtedly be lighter.

OldsCOOL

'86 Pro Series 760, 531c and even with the small for me 52cm, is very flexy. My first ride I stomped on it, full-on out of the saddle and experienced the predicted ghost-shift. The bike is too nice to ride hard and since then have learned not to treat the lovely 760 like my Cannondale Criterium.

The Golden Boy 

The Reynolds transfer chart at the Equus page has the undeniable description:

"REYNOLDS 531 CLUB SPORT transfer, a cycle bearing this transfer has top seat and down tube BUTTED in REYNOLDS 531 and head tube, BUTTED steerer. TAPER GAUGE forks, seatstays and chainstays manufactured from specially cold worked chrome Molybdenum tubing. Designed for fast sports and touring."

So, while it doesn't specify 501, it does specify CrMo.

The Golden Boy 

That's what I would expect out of the bike based on my experience with the 730.

The only thing I can think of is that the 720 got a special (different) 531c tubeset,


To muddy things further, I also have an 86 400 Elance with 531 main tubes and Trek (Tange) CrMo fork and stays. The geometry is actually more aggressive than my 730, the wheelbase is only slightly longer than the 730- but it rides as solid as the 620 and 720.

It's not all about the geometry, and if the tubes between the 730 and 720 are technically the same, it's not all about the tubing.

OldsCOOL

And at that point you can tend to explain the fun right out of it. It's all good tubing, if the geo fits and components are decent, you have a nice bike.

T-Mar

Read it again, carefully. The main triangle is Reynolds 531(i.e. MnMo). The forks and stays only are CrMo. There is one sentence specifying the material of the main triangle and a different sentence specifying the material of the stays and forks. Basically, 531CS is a mixed alloy tubeset. Consider it tretubi 531 (with a slightly heavier gauge seat tube) with 501 stays and forks.

Chombi

"CS" = "Club Sport"??...... That's a bit dissapointing, cause I thought it meant "Competition Special".........
While did Reynolds even bother with the kinda underwhelming sounding tubeset model designation?

The Golden Boy 

That's what I said.

It does not specify that the CrMo is 501.

As I understand 501 is a specific non-seamed tubing, not just general CrMo Reynolds tubing.

T-Mar

My apologies. However, at the time, 501 was the only CrMo tubing mentioned in Reynolds literatrure and the gauges of the 531CS forks and stays match 501, so it is the only known candidate. Other Reynolds CrMo tubing like 525 and 500 were introduced later.

BTW, 501 was seamed tubing. Reynolds had made its name proclaiming the superiority of its MnMo tubing over CrMo. The only way to save face when they introduced CrMo was to introduce it at a lower price point and the only way to do this was was to use seamed tubing but they didn't want to advertise it. If you look at the mid-1980s Reynolds literature, they proudly proclaim 753 and 531 to be seamless, but don't mention whether 501 is seamed or seamless.

Bruce27

Please vote in my missing poll. Kindly send me the link if you run across it.

Pemetic2006

I actually did vote in that but I can't remember what the thread title was.
When I first heard of this issue it bothered me, a bit, but from what I've read it seems rather isolated. When I finally get this bike ready to ride on some regular basis it will be on paved roads and I won't really sweat it too much.

The Golden Boy 

No apologies necessary. And thank you for the information.

This is interesting all around about 501. I would have figured Reynolds, with its interest in Raleigh, was the producer of all different type of tube sets, from hi-ten to 531. It seems that the weight and tensile strength I've seen posted about general CrMo/4130 tubing puts it at a 'station' "beneath" 531 anyway- but considering any costs to produce ANY seamless tubing- it totally makes sense to place it lower and attempt to maintain the superiority of 531. Which- around this time, 531 had really lost it's cachet- gone were the onion skin decals that were impossible to remove and add to another bike- and looking too intently would flake off the decal. So just going to the "regular" decals was a sign of where 531 was in relation to the Columbus tubings of the day.

I find it also interesting that by 1986 Trek was using 531 main tubes in their 2nd to entry level offerings and by 1987 it was used in the entry level Trek bikes. Of course- as it's often pointed out, Trek started out their "entry level" at a much higher point than other makers.