Steel vs. aluminium direct mount chainrings, wear rate

How much difference does the material make for wear?

Currently running Shimano SLX M7100 direct mount which is a “one piece” permanently (allegedly!) bolted together ring and spider. The ring is made of steel and the spider of aluminium, presumably for longevity and weight reasons. Normal price is £25-30.

All the aftermarket options I see are true one piece aluminium, at double the price and half the weight (e.g. SLX 121g, Unite 68g). So if I switched to Hope for their 155mm cranks, am I going to be stuck with aluminium chainrings and replacing them much more often at double the cost?

Aluminium has no place in a drivetrain if you ask me.

I am tight though and expect maximum longevity out of anything I buy.

I agree – I intentionally run Deore cassettes as all the cogs are steel, and for my usage and fitness those are the ones that wear out first.

There’s a few steel options in teh aftermarket, Mwave do a couple of bcds, Sunrace as well. No idea what hope compatibility is like, do they offer spiders? Mine are all random cheapo ebay 104bcd no-names. For me it’s a no-brainer as long as you can actually find one that fits- they last forever, the retention lasts better too, your chains live longer and that means so do your cassettes.

Ah they do indeed offer a 104 spider, sold in many places but not listed on their website as a separate product. You buy the cranks with or without a spider.

Was thinking about this exact thing this week. Raceface cinch alu rings are almost 4 times the price of the steel. Admittedly, they’re much, much lighter, but I bet the steel ones last forever.

Depends entirely on the grade of materials that they’re using and if they’re not telling it’s difficult to make an informed choice!

Machined alu parts are often 7075 but could even be 2014 – which are harder and stronger than many grades of steel.

I’ve a Blackspire snaggletooth on an XO1/GX mix and it’s done about 5500km so far. Both mechanic and I (the bike went in for bearings a couple of weeks ago) think it’s good for maybe about 3000kms more.

From my experience using 2 sets of Race Face cinch cranks the steel rings last 2 – 3 times longer than aluminum ones.

Both sets came with alu rings, worn enough to change after about a year, then replaced one with steel and one with alu.

Actually, the steel one I had on my hard tail was looking a little worn end of last year (after 2 years use) So I replaced it with another steel one and put it on the other cinch crankset, which is on a SS bike. It’s still running fine 😁

I get plenty life out of blackspire snaggletooth rings so don’t really consider heavier steel ones, plus I like a bit of colour and snapped a few up at £20 so can’t complain about longevity per pound, but it’s got me thinking about chain longevity differences when using steel vs aluminium rings, has anyone done any research on it.

Aluminium has no place in a drivetrain if you ask me.

Hmm, my 165bhp 140nm ktm had an aluminium driven sprocket. There was no perceptible wear on the teeth after 10000miles of me exploiting many of those horses. It really depends on the grade and treatment. Aluminium oxide can be hellishly hard.

the contact surface on the teeth of a 1x chainring is quite a bit wider than the teeth on the cassette sprockets as well.

You can add Uberbike, Praxisworks, Wolftooth and Burgtec to the steel ring options as well.

And specialized, and absolute black, and quite a few others, it seems.  Praise be for e-bikes!

I’m currently using alloy sram direct mount rings and they last pretty well. Feel very light vs the steel ones. But the steel ones are cheapy cheap and last almost forever without wearing much

Machined alu parts are often 7075 but could even be 2014 – which are harder and stronger than many grades of steel.

Not really – even mild steel has a hardness and strength which significantly (>15% at minimum) exceeds 7075-t6 and 2014-t6.  Carbon steel even more so and stainless more than even that.

Stiffness to weight is where Al alloys work out better, but in a chainring where the geometry is largely fixed due to the interface, steel will always be more durable.

Not direct mount but I have a cheap steel SRAM chainring on one of my bikes and it’s lasted (still going strong) much longer than any aluminium ones I’ve had on it.

It doesn’t weigh a lot more and last forever (or at least a long time)

Not really steel vs alu, but the one thing I found with Hope DM chainrings are that you’re VERY limited with options. When I was looking, I could only find chainrings by Hope, Burgtec, and Superstar – all alu.

Okay not that useful for a shimano drivechain but I really rate the cold forged SRAM alumium chainrings, almost as light as their fancy £80 machined ones for £30ish.

I tend to get around 1200-1500 miles out of one which is fine by me.

Aluminium has no place in a drivetrain if you ask me.

Not totally sure I agree, I think it comes down to the intended use for the bike, the weight saving of Al Vs it’s wear rate is the debate really.

(carbon) Steel will still rust of course and that still needs to be managed or it can lead to future issues for with the wear and degradation of other parts within the drivetrain, same as with a chain or cassette.

But I’ve not found Aluminium rings to be a huge problem, it’s more the conditions and frequency they’re used under that causes issues;

I’ve recently had to retire a Superstar N/W ring from my gravel bike after it finally developed a bit of a ‘hook’ to the teeth, that was after about 2700 miles and a few chains, that seemed reasonable to me on a bike that’s been ridden in all weathers and types of muck, the Aluminium Stronglight rings on my road bike are approaching 6000 miles old and show no real signs of needing replacement, I reckon they’ll make 10,0000 miles without issue.

MTBs do tend to have smaller chain rings and thus load is shared over fewer teeth normally, with extra moisture and abrasives added, I think a better justification is there for a steel ring if your running 1x with a 32t or smaller and chasing longer life on a bike used year round, but being honest about it, these days my MTBs (both with dinky N/W rings) don’t really do the annual mileage to justify changing to a more durable Steel/Stainless Steel ring these days, If I was getting less that 2 years out Al rings them I’d consider swapping to steel but that’s not the case.

I suppose the only other question specific to DM rings is the interface between the ring and the crank, can a steel ring chew that spline pattern where an Al’ Ring might be the sacrificial item in the interface if something has to be, has anyone observed an issue with this or is it just hypothetical?

I suspect the type of lube makes a bigger difference, if you use something like muc-off grinding paste, you’re just wrecking whatever you’ve bought at a far faster rate than necessary.

Need to drop a chainring size with shorter cranks, but turns out 104BCD isn’t designed to go smaller than 32T.

Wolf Tooth do a steel 30T (not currently in stock), but only in a tooth profile that isn’t Shimano compatible. The photo shows the space issue with the bolt holes.

Given the space issue and lack of need, the eMTB targeted ones I found don’t go smaller than 32T.

I’m no material scientist, but I looked up on https://www.makeitfrom.com/ some of the materials mentioned above and by manufacturers who state it.

Brinell hardness values:

2014-TR alu – 140
7075-T6 alu (most common) – 150
4130 Cr-Mo steel, quenched and tempered (e.g. Praxis) – 300
416 stainless steel, hardened (e.g. Wolf Tooth) – 320

I expect it’s not a simple as comparing those values though.

even mild steel has a hardness and strength which significantly (>15% at minimum) exceeds 7075-t6 and 2014-t6. Carbon steel even more so and stainless more than even that.

Yeah thanks for correcting me on that, the yield is much more what I’m thinking of. Anything better than S235 is going to be harder than alu 7075 T6!

I have a couple of Wolftooth Stainless 30t and they are spendy but a thing of beauty.

Need to drop a chainring size with shorter cranks,

You only need to do this if you’re struggling in bottom gear and a lower gear would help. If bottom gear remains low enough, just keep using your existing kit

Yes, by need I mean I need, not that I’d read that it’s needed. I’m just about managing in bottom gear, so don’t want it to be any higher.

The gain ratios for a 29er with 51T biggest cog on cassette are as follows according to this calculator:

30T 170mm = 1.28
32T 170mm = 1.37

30T 165mm = 1.32
32T 165mm = 1.41

28T 155mm = 1.31
30T 155mm = 1.41
32T 155mm = 1.50

All the aftermarket options I see are true one piece aluminium, at double the price and half the weight

Only if you buy western brands. Direct mount aluminium rings from ali express cost about £8 each.

That sorts the cost issue. Still wasteful and effect on the rest of the drivetrain.

Just replaced my GX aluminium chain ring with a steel NX one. Not much heavier and was loads cheaper. I got 5 years and about 3,000km out the aluminium one so would expect more miles from the steel one. Doesn’t get ridden much.

My aluminium GRX chainring on my CX bike lasted 3 years and about 5,000km, which I was pretty impressed with.

Surly singlespeed stainless steel chainrings I’ve used in the past can outlive the bike.

Aluminium has no place in a drivetrain if you ask me.

Whatever you do, don’t look at fiber-lyte chainrings. And I would accept that outside of indoor/TT/best bike, carbon probably has no place in a drivetrain 😉