A1 alloy Specialized Rockhopper vs M4
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??Posted 4 years agoNormal ManSubscriber
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.Posted 4 years agobreatheeasyMember
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.Posted 4 years ago
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.Posted 4 years ago
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.Posted 4 years agocrashtestmonkeyMember
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.Posted 4 years agoesher shoreMember
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 treatmentPosted 4 years agocrashtestmonkeyMember
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?Posted 4 years ago
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