Any insight into the qualatative differences b/w these two materials? I'm thinking of trading in my 06 Jamis Aurora (great bike, Reynolds) for a Cross Check (4130). I've read quite a bit on this forum about the perceived overpriced Surly products, mostly due to its "cheap" 4130 frame. Is the 531 superior? Equal? Inferior? If it's at least an even trade in terms of the frame, I'm doing it. Thanks in advance.

Don't let people tell you the Surly frames are straight guage chromoly. The main triangle is double butted. The chainstays and seatstays are straight guage. FWIW I love my crosscheck and ride it more than my "nicer" bikes.

If the 531 frame is full 531, it'll likely be a little lighter, though a little less durable, than 4130. Though, unless you're commuting down a mountainside (sans road) either will be a good ride.

Good question. I'm interested to hear from some other more knowlegable folks. This thread might get a better response in the mechanics forum or from the rec.bicycles.tech newsgroup.

As I understand it, 531 is a proprietary brand from Reynolds. It's a similar alloy (1.5% Mn, 0.25% Mo, 0.35% C) to 4130, but the Reynolds company applies some extra heat treating to make the tubing stronger (??). I don't know if that equates to lighter, such as 631 or 953(!), but it is a step up from basic 4130. Please, someone with more info step in...

That being said, I've got a "cheap" 4130 Cross Check and I really enjoy it. Surlys may be a bit overpriced in terms of frame technology, but they're such a versitile and rugged design.

Thanks for the replies--very hellpful. I suspected as much, and for what I'm doing (commuting), it seems to be a wash b/w the two. Glad to hear you all like your Cross Checks. Now that I've got your attention--thoughts on the chainstay length of the Cross Check v. the LHT? The LHT CS length (almost 18 inches) seems a bit much, the Aurora (17.32 inches) is just about right, and the CCheck comes in on the shorter end (of my comparison) at 16.7. How material is that difference in terms of ride quality? I know the longer the CS, the "smoother" the ride. Would you describe your CChecks as "smooth" or more "agile"? Again, thanks in advance.

Main advantage to longer seatstays is that they let you carry panniers without heel strike problems.

Check the link below and look at the entire page:

https://www.anvilbikes.com/?news_ID=49&catID=3

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My Cross Check is the smoothest bike I've ridden - smoother even then my suspended mountain bike and hybrid. It's the bike to use when my bag is heavy, or I just feel the need for a gentle ride. I assume this is due to the longer chain stays, fork rake, and relatively relaxed geometry. It's well behaved and versatile, but I can still get down on the drops when fighting a head wind.

You're thinking too much. Performance and comfort depend as much on fabrication technique and parts selection as on frame material and geometry details. Do some research, then do some test rides.