A1 alloy Specialized Rockhopper vs M4

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  • A1 alloy Specialized Rockhopper vs M4
  • timb34
    Member

    About 3 years ago, Specialized made their Rockhoppers with their own M4 alloy, and they were regarded as being quite good frames. Certainly better regarded than the A1 alloy Hotrocks.

    Rockhoppers are now all 29er, and are all made from A1 alloy instead of M4.

    Has anyone tried both an older one and a newer? Are they more or less equivalent, or not as good??

    timb34
    Member

    No-one have any opinions on Specializeds alloys? Is it all made up?

    Premier Icon njee20
    Subscriber

    There’s more to it than that. I’d be stunned if anyone could honestly tell the difference between the two if you took the stickers off.

    Wouldn’t worry about it.

    timb34
    Member

    OK, thanks, I’d thought that there might be more of a difference between them.

    Premier Icon althepal
    Subscriber

    Had an m4 rockhopper from about 2003 (?) And it was a nice light wee hardtail.. you could certainly feel the thiness of the tubes/butting when doing the “ping” test..

    timb34
    Member

    I had a 2010 one, and really liked it. The chainstay cracked over the summer and Spesh Europe are offering me a deal on a complete 2014 RH.

    It’s an A1 alloy frame, and a crappy fork (XC28) which are giving me pause for thought.. All opinions would be interesting!

    bigyinn
    Member

    I think from memory the M series alloy tubes were supposed to be lighter and had a better fatigue resistance.

    Premier Icon Normal Man
    Subscriber

    Over summer I thought I’d get a 29er HT for general xc duties. As I’ve become a bit of a Spesh fan over the past few years they were my first port of call, especially as I can usually get a good deal as regular (read serial) bike buyer!

    Anyway, I went to try a RH pro but, despite a good deal being offered, I felt it was a bit heavy and lethargic. Not a bad bike but quite basic.

    I upped the budget and looked at a Carve (now Crave for 2014) and ended up doing a deal on the Expert model. The air fork, lighter wheels and frame (M4) plus 2×10 suited me better.

    I’ve made a couple of small changes now and love it! It is now my ‘go to’ bike of choice.

    Premier Icon kcal
    Subscriber

    Have had an M4 Stumpjumper for 15 years. So not bad fatigue resistance.
    In fact I’ve got another (second hand) of similar (1998) vintage, still going too.

    breatheeasy
    Member

    Has an old Rockhopper with an A1 frame and a Stumpjumper with the M4 version.

    You’d never be able to tell the difference. IIRC I don’t think there was even much in it weight wise.

    Both are still being used and abused by friends I’d sold them on to so fatigue life seems okay for both.

    Premier Icon njee20
    Subscriber

    Have had an M4 Stumpjumper for 15 years. So not bad fatigue resistance.
    In fact I’ve got another (second hand) of similar (1998) vintage, still going too.

    Really? The S-Works didn’t become M4 until 1999, and the Stumpjumpers were M2 until 2002 (when the S-Works became M5). There were no 1998 M4s.

    Premier Icon kcal
    Subscriber

    doh. got my M2s and M4s mixed up, sorry – lot on my mind this a.m.

    I stand unconditionally corrected. M2s have been resilient, anyway 🙂

    Premier Icon njee20
    Subscriber

    You’re forgiven, clearly I’m a massive Spesh frame geek 🙂

    esher shore
    Member

    A1 is 6xxx aluminium, M4 is 7xxx aluminium.

    In reality the M4 frame is lighter as the stronger alloy allows thinner walled tubes and smaller diameter tubes which also give a less harsh ride.

    timb34
    Member

    Thanks for all the comments.

    A quick trip to my local specialized store let me compare the A1 Rockhopper and the M4 Crave, helpfully next to each other. Difference in weight seems pretty minimal, but the slimmer back end and smoothed welds on the Crave make it a lot nicer looking (also has postmount rear brake mount and no rack fittings) .

    The M4 frames also make a much nicer noise when flicked with a fingernail in the absence of a shop assistant.

    The M2s were metal matrix composite, a fancy material that was a bitch to machine, and replaced with M4 which had similar marketing fairydust/BS sprinkled on it but was a conventional aluminium alloy.

    the M4 frame is lighter as the stronger alloy allows thinner walled tubes

    Difference in the actual alloy used is of little consequence. Back in the day 6xxx was seen as “better” than 7xxx as all the top-range, US-made alloy frames (eg. GT Zaskar) were usually 6061-T6, lesser models (GT Avalanche) were far-eastern and usually 7005-T6. This had everything to do with what was locally available, rather than consciously seeking specific characteristics of different alloys.

    esher shore
    Member

    @crashtestmonkey

    the 7005 alloys allow for a lighter frameset, simply because you need less material for the same strength as 6082 or similiar 6XXX alloys: you can use a thinner wall or smaller tube, which also changes the ride feel

    i worked extensively in 6082 (HE30) in the UK making prototype frames, which always ended up heavier than the 7005 frames my factory in Australia was making my production frames from. we could not source 7XXX tubes in the UK otherwise i would have jumped on them..

    A big problem with 6082 was the expensive, time consuming and temperature critical T6 heat treatment; compared to 7005 frames which would harden in their packaging whilst ‘on the boat’ following post weld alignment

    I used to sell a lot of USA made Zaskars whilst working at one of the UK’s leading GT dealers and we had a large number back cracked due to poor QC during heat treatment

    If we’re credential-waving I used to research and develop Al alloys (7050 n the US for Alcoa for use by Boeing and 7475 in the UK paid for by BAE who weren’t happy with bits of the Eurofighter/Typhoon cracking…). 7xxx does harden at room temp but T6 is a specific treatment for peak ageing (the 7050 was usually over aged to enhance specific properties).

    I was making the point that alloys aren’t chosen for their theoretical properties, which I guess you’re agreeing with as a frame-building practitioner. 7xxxx might allow frame manufacturers to be lazy and QC failures are exactly that (Ti frames, anyone?). Cannondale and Klien were the kings of fat tubed thin walled frames and all their US frames were 6xxx because at the time that was being churned out in US mills, but it was marketed as being a better alloy (when in fact it may well have been a b*gger to heat treat properly) . ‘Course now cannondale are all about the carbon, remember the Raven with the alloy spine which tied the materials together for the marketing guys?

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