[Closed] Calling all engineers, why no high performance steel MTB rims?

You could make one but to be competitive weight wise it would be coke can thick and I dont think that needs any explanation.

It's all about material density and stability to local impacts. Thin wall high strength and stiffness is all very good until you add a localised impact.

I would think that to get the weight competitive the walls would be so thin you'd not be able to extrude a shape that complex, without going to some super exotic steel alloy. Which would need to be pliable and easily extrudeable. Which would make it a bugger to build into a wheel, and quite easy to bend. If you see what i mean. So you'd have to go thicker, and heavier. And you'd still end up with sticky up bits of rim that'd be easy to dent. And it'd be very expensive. And you might need to muck about with heat treatments and..... oh god, lets just use aluminium....... 😉

And that's a grail isn't it? Wide, deepish, lightweight racey CX rim? And that looks like some nasty, heavy commuter tyres...... You might be better off with something heavy (500g or more) and boring from mavic/velocity/etc for commuting wheels...... might be a bit tougher, and cheaper to replace if it does go.

A 90k clumsy porker needs a 3d woven carbon and plastic rim

I've quite often pondered about titanium rims double wall construction with stainless eyelets not built round weight weenie but for touring in a massive loaded bike off road kinda way.

Also stainless hub body's and freehub

Hi Ghostly. Yes it's a Grail. When the wheel was built (Rohloff hub) I said it was for commuting with a spot of kerb jumping to get through the traffic - just that that kerb bit back! Tyre is a Conti Sport Contact 2 37mm. I'm replacing the Grail with a Mavic A319 (first wheel build attempt...)

But I'm specifically talking about MTB wheels here. I've fatally dented a WTB Laser Disc, an XT M785 and done a good job on a DT E1700 (straightened and still airtight. I don't race and I'd be prepared to take a weight penalty for the confidence of knowing my rims are bit more resistant. I'm wrapping the E1700s in DH High Roller 2s for the Alps at the end of July.

Have the advances in steel alloys in recent decades not meant that we can make better steel rims; not the lightest but with a good security pay off?

Titanium is still denser than aluminium so you would probably still end up heavier.

I wonder what a carbon reinforced PEEK rim would be like.

I don't remember steel rims being heavy as such; I remember them more for their shocking braking, which you'd negate with disc brakes. Weren't steel rims rolled rather than extruded? Pretty sure I've seen them being made on one of those old pathe films.

Where these steel rims back in the day when 17mm was wide?

I don't think the rims are the problem 😀 some other options; more pressure, Pro Core, solid tyres, or change your riding style.

Hi Fooman, I know that the rims aren't the source problem but I can't magic myself better and it's getting expensive on the way to improvement! I don't run very low pressures. Those commuting tyres would have been at 5-6 bar. Once the Contis are done I do plan to get some Tannus solid 32mm for the commuting but that doesn't solve the MTB issue.

If you don't run low pressures on MTB and use big, high volume tyres how are you managing to dent the rims?

What pressures are you using and what tyres?

I have only dented one rim in my life and that was via a cocked up kerb hop on a 700c rim with 25c tyre (doesn't matter how high the pressure in that case the kerb will still get to the rim).

Hi Kerley,
WTB Laser Disc with WTB Bronson (as stock). 2.2" I think. Rear wheel. Probably had 3-4 bar as it was early days back to mountain biking. There may have been a fault on that rim as it just exploded JRA, fracture right across the spoke hole.

XT 785 with Conti Mountain King 2.4". Rear wheel. Around 2 bar. Was descending a pebbly trail slower than my friends when I suddenly flatted (snakebitten tube) and found the rim section crushed (not just bent rim but the round section deformed).

DT E1700 with Maxxis Minion DHR2 EXO tubeless. 2 bar. This was just a messed up jump of a drainage channel. Not square edged but angular and the rear impacted making that very nasty noise. I could straighten this one and for downhill I've just bought HR2s with DH casing.

I know I need to learn my bunny hops etc but I'd still be interested to know whether much tougher rims are available, and why can't they be done in steel.

Cheers.

Hmmm, for road bike/29ers this company might have something - http://www.dutchbikebits.com/traditional-bicycle-wheel-rims.

Rims are marked 28 x 1 3/8 (622) in stainless. But would they be strong or just heavy?!

I wonder what a carbon reinforced PEEK rim would be like.

Flexible.

so you had a flat that caused damage to a rim, a odd/heavy impact that damaged a rim, a possible structure issue that failed the rim

cant see what the problem is ? steel wont help, as the next weakest part will be the issue , spokes?

Spokes are already stainless steel! No, my thinking is that if I accept that I am a graceless beast, at least have rims I can straighten more easily without that nasty alu fracture characteristic.

spokes break at the nipple or shoulder, then the hub!

dt swiss rims normally known for being soft, but not all of the range? maybe look there

I can't speak for rim material but I weigh 110kgs and ride a Hardtail down things faster than your average (weight) rider.
I used to mash wheels and frames on a regular basis.
Everything changed on my second visit to the Alps when I ran out of money to buy new brake pads after melting 2sets in almost as many days.
I had no choice but to ride with almost no brakes and was forced to keep it smooth, pick good lines, anticipate well in advance and follow classy riders. Now I just go through saddles, I have even bent a Thompson seat post!
Quality wheel builders are worth their weight in gold and I'm looking forward to a pair of 29er wheels being built next week to replace the factory set on my new (second hand) Scott Scale.
Skills courses are also just damn good fun.

well built wheels here

I did a skills course last year in the Alps but it was €35 an hour!

Interesting thought OP.

I guess the culture has been aluminium for braking (I guess metal matrix was too hard to extrude) so there's been no thinking around it.

I doubt wall thickness would be an issue - it isn't on steel frames 🙄 I imagine it's a combo of no one thinking about it and/or the expense/difficulty of extrusion.

And would there be any benefit? Alu frames are lighter than steel by a way.

I wonder what a carbon reinforced PEEK rim would be like

Such things exist ,not for a bicycle at this time but it wouldn't be a big jump from one industry that's tried it to another.

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Bound to be something like these about for mountainbikes. Skyways do 24" wheels and there was talk a few years back of a 26" version. Perfect for heffalumps.

if I accept that I am a graceless beast

That's the spirit! 😆

You don't need 'lessons' on being smooth, you just have to put a bit of thought into your riding, experiment and practice. It's free and it's fun. Folk often say they don't have time to practice 'skillz' but i don't buy that - any time on a bike can be practice time.

but I'd still be interested to know whether much tougher rims are available, and why can't they be done in step

A tougher rim could be made my just using more alu in the construction without caring about weight (In fact you could pick already available tougher rims than you have been using, isn't a WTB Laser Disc an XC rim for example?) Steel would still not be a better material as it would just be heavier for the same strength.

Why does nobody make a heavy steel rim (that would rust), simple answer - because very few people would actually buy one

@Kerley, the WTB Laser Discs were as stock on an steel XC hardtail. I have a 160mm full sus now, and surely DT's E-series wheels should be strong enough. As a solid unit of material even bog standard steel is far stronger, stiffer and harder than aluminium, the issue is we're dealing with hollow volumes and shapes. In the Cotic Rocket explanation Cy talks about how steel's density penalty is excessive for XC bikes but becomes viable for for heavier duty machines. Why can't the same apply to wheels, especially (and I don't know if these alloys are appropriate for wheels rather than tubes) when we have such grades as Reynolds 853, 931 and 953; the latter two of which are stainless and thus won't rust (much, my road bike is 931 and if you really don't look after it there can be some discolouration).

Look at chainrings, aluminium is a crazy material for that but now that SRAM is selling steel ones, at a vastly reduced cost, there should be a good market. I've got a WTC stainless one; slightly more expensive than most alu narrow-wide rings but vastly more durable.

There must be an engineering solution point at which steel's strength, toughness and hardness outweigh its density.

Strength to weight wise aluminium is the winner but tends more towards brittle rather than ductile failure, the steel we already use in wheels is used more for it's tensile strength and even that gets pared down to the minimum...

Wheels are basically a mixture of materials and construction to give you a structure that balances weight against strength and cost.

Of course not all that long ago steel was the default rim material, the manufacturing technologies of the age basically worked around rolling sheet in to the desired shape and then either painting or plating it for corrosion resistance.

A lot of areas of manufacturing moved away from steel when aluminium became easier to use, extruded aluminium profiles deliver a better cross section for less weight, it requires a bit less energy to process aluminium (lower melting point) better heat treatment processes offset annealing / work hardening from forming and fabrication (although also impact that energy saving). Plating (anodising) aluminium is well understood and the finish is arguably better for corrosion protection.

The other thing to remember is that MTBs and frequently bashing rims into rocks is a relatively recent development, up until say ~40 years ago most rims were expected to be used on relatively smooth surfaces, the odd kerb edge or pot hole impact was an infrequent risk not too high up the agenda. ~25 years ago MTB specific rim profiles arrived, rather than manufacturers using a 559mm rolled touring rim profile.
However rim brakes were still the main way of stoppingn so the best available construction remained extruded aluminium profiles with flat sides. "modern" disc specific rims have only really been about for the last 15 years or so.

And of course Composites are now making their way into wheel construction and giving all sorts of new possibilities and options for how a wheel is constructed and what sort of balance of weight/strength/costs can be achieved, I very much doubt anyone will choose to go back to steel just to achieve greater impact resistance for DH which is really a relatively niche application...

@cookeaa, thanks very much for that summary, in historical perspective. I follow your argument on specific strength ( https://en.wikipedia.org/wiki/Specific_strength), which is listed here as c. 60 KYuri versus c. 200 for 7075 (though balsa is higher still!). But oh for some lovely cheap though slightly heavy impact resistant rims; maybe like a Zee as opposed to a Saint!

added to which any weight gain at the rim is in the worst possible place.
wrap your rims in more air or more tyre or a combination of both. oh, and try to stop smashing them off stuff. 😀
OK - TBF the 'pebbly' scenario described could have been due to a tyre that had already lost air for all you know. the wtbs aren't ( as far as i know, and i had some of those on my old 5 ) renowned for being particularly strong, and DTs were known for being prone to dents, though whether this still holds true for the ones you mention i do not know.
like all bike stuff, bontrager's law applies. choose your poison.

why the hell would anyone want a stainless hub!?

[quote} There must be an engineering solution point at which steel's strength, toughness and hardness outweigh its density.

Very probably, but it may still end up with a rim that weighs much more than equivalent alu based rim and again a rim that nobody would buy (as 99% of people don't have a problem with Alu or carbon rims)

I suppose the real problem you have though is the nature of the failure OP, your rim took a heavy edge impact with enough force to overcome the cushioning/load spreading capacity of the tyre a similar edge impact on a steel rim would have a similar result unless you beefed the whole section up significantly, resulting in a very heavy rim...

The engineered solution already in place is about as good as you're going to find with current materials, which is of course a modular construction system for wheels, that allows pretty much every component to be replaced if it suffers a failure including the rim...

I would call what you have there a "safe" failure in so much as the rim bore the impact, the damage remained local and the wheel didn't collapse, (I assume you were able to come to some sort of controlled stop)...

Everything has its limits, make an indestructible rim and those stresses just get passed on to another part of the bike, so what do you want to break instead?

I just took the tyre off the Grail and the rim is folded right into the bed. So the rim wrecked but no actual visible damage to the body of the rim. The tyre didn't flat somehow and I had to do another 35km on it with only a very slight loss of true...

For the MTB, what I obviously need is a completely solid steel wheel, not rim, wheel! That looks like a 650b doesn't it? 😀
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ghostlymachine - Member
I would think that to get the weight competitive the walls would be so thin you'd not be able to extrude a shape that complex, without going to some super exotic steel alloy....

With the low pressures being used in plus size tyre these days, there could be whopping great holes in the rims. With formed edges they wouldn't lose stiffness compared to without.

Before most of you were born my mountain cycling was done on steel rims because the alloy rims of the day were made of cheeseinium.

The steel rims were not invulnerable, but they could be bashed or bent back into shape trailside. I even carried a wee block of wood as a form for that very purpose and the adjustable spanner for wheel removal did the bending. (Riding rocky singletrack with 1?" tyres usually meant a ding every so often).

With fatter tyres and rolled edges, they would be quite usable. My stainless 700c Westrick steel rim weighs 750 gms so a fat tyre rim with holes wouldn't weigh much more, and possibly with a higher grade of steel, maybe lighter.

As for braking, it wasn't too bad with the red rubber pads*. I used Dunlop stainless steel rims which were etched on braking surface for better water dispersion.

*That's relative of course. 🙂

My memory of steel rims involved Weinmann calipers that flexed alarmingly and squealing brake blocks that did relatively little in terms of decreasing velocity - good riddance!

It's not just a matter of weight, it's to do with manufacturing techniques. Alu alloys can be extruded in complex, strong, sections and then bent into rims. That's much nore difficult with steel and Ti because of their higher melting points and the way they change properties after heating / cooling.

dovebiker - Member
My memory of steel rims involved Weinmann calipers that flexed alarmingly and squealing brake blocks that did relatively little in terms of decreasing velocity - good riddance!

My rubber pads could lock the wheel, but that's more of a commentary of the amount of grip the tyres had I suppose. I had GB Coureur 66 centre pull brakes, I don't remember much flex other than in the levers and cables, but that is a very long time ago.

I wonder how well steel rims would stop with something like the material used on disk pads? Possibly too much flex in the brake surface to be any use.

@epicyclo, thanks very much for your comments. The capacity for repair is something like what I had in mind.

Seems like these guys have a range -

Bottom of that PDF they have bicycle rims and the 'WO 38' model in 26x 1 1/2 comes out at 584.4 mm diameter; so less than half a millimetre from 650b. You know, I'm almost tempted to try this just to be a difficult bugger 😀

So when you dent the steel rim and squash the edge of the rim what are you hoping to be able to do?
Wouldn't think you could easily reform the rim.

Or are you thinking the hollow section of the steel rim would not dent because thin steel is so strong?

If you want to give it a whirl why not. I would be interested to hear how it goes, what sort of weight the rim/wheel build comes to and just how tough it is when you start ploughing the rock gardens...

kerley - Member
So when you dent the steel rim and squash the edge of the rim what are you hoping to be able to do?
Wouldn't think you could easily reform the rim...

I never managed to do unfixable damage. It was usually the braking surface bending in or out. When it got straightened properly the wheel would run true.

Of course big drops and the like were avoided because that was usually a recipe for folding your forks or kinking the frame, ie I rode knowing the bike was very breakable.

Spoking was traditionally 32 front and 40 rear, (I preferred 36 front), so the wheels were reasonably strong.

gaidong - Member
...Bottom of that PDF they have bicycle rims and the 'WO 38' model in 26x 1 1/2 comes out at 584.4 mm diameter; so less than half a millimetre from 650b.

That's a Westwood* rim section, and it would fit. I used to like them offroad because they were a bit wider and the rolled edges meant less snakebites, but getting any decent braking on them was a problem because they're designed for rod brakes.

You could use a calliper brake but that never worked well for me. With a drum or disk there would be no problem.

I didn't see any mention of what the rims are made from, although they do look like steel.

*In yesterday's post I referred to this as Wellworthy - brain fade moment. 🙂

I haven't bothered to read the whole thread but here's my suggestion to the OP; Get a fat bike.

Not because the rims are stronger, but the fully rigid nature if the beast will force you to get loose, which in turn will save you some rims and make you faster.

Fat Bikes - saving you money since 2013.

Any rigid bike will get you picking better lines, not being as clumsy or expecting any suspension to soak anything up.
Riding rigid bikes for most of my life combined with only ever denting one rim may not be coincidental.

However, that is not really solving the problem as most people don't want a rigid bike (which I can fully understand)

I have a fat bike on the way (Cube Nutrail) but it has a Bluto. Was keen on a rigid fork for it but that's for later in the year.

I've asked the company for the steel grade, whether stainless or not, and mass. If they're cheap, then why not give it a whirl. I said in my first post that I didn't think steel would be undonkable but if I do, then yes, you can straighten steel! Was thinking 36 spokes back and front. If you're doing bombproof then do bombproof. I'll let you know what the company says about specs. Doesn't hurt to experiment does it.

Doesn't hurt to experiment does it

All depends what you mean by hurt. I would personally see it as a complete waste of time and money to be buying rims and spokes just to see if steel rims (which will be heavier and will rust) would be more ding resistant/fixable than alu.

So yes, it would hurt my time and my money but carry on - I'm sure everyone will be on steel rims in 10 years time.

They have to be rolled, not extruded, so you can't make as strong shapes. And the high density means low material thickness which makes them bendy and you can't go narrow like with frame tubes without negatively affecting how the tyre is supported. In the early '90s I remember my Dad constantly buckling the steel rims on his MTB...

My Guv'nor has got steel rims. And, they're mahoosive, at 635mm. Don't think anyone does MTB tyres that size though.

[quote=flap_jack ]And, they're mahoosive, at 635mm. Don't think anyone does MTB tyres that size though.

I'm sure we need another tyre size niche...

I just heard back from that Italian company:
"d.spreafico@italcerchio.it
09:35 (39 minutes ago)

to me
Good morning,
the rims are available at the price of Eu 11,39 + italian tax of 22% each
Weight around Kg.1,00"

I asked again for alloy type and they're chromed steel. I'd only be interested in stainless so I'm out but I'm sure they'll be fine for classic restoration projects. At that price you could almost have disposable rims though 😀

A 1 kg rim! ouch. Just make a ghetto pro-core with some road tubs.

cynic-al
I doubt wall thickness would be an issue - it isn't on steel frames 🙄

yes it would and is.

Using a high strength steel alloy you could make a really thin wall and light wheel/frame/anything and it might also have suitable stiffness (read as nice and springy) but it would buckle as soon as you looked at it like an empty beer can.

It is exactly how we make aluminium aircraft - thin wall, high strength aluminium alloys. Wing skins in tension are incredibly thin and can take huge whole structure deflections but locally they are very easy to damage.

If you are building any steel bike rim down to a weight that competes with an aluminium one it will have to have thin walls and stones WILL dent them. Deep section aluminium MTB rims are bad enough for stone dents. Remember stiffness is non-linear with thickness unlike modulus and it is this local stiffness that resists damage from objects and those local areas of damage end up affecting the stability of the whole structure and can lead to buckling as the load is no longer being carried along the structure as it was designed.

You can make a MTB rim out of steel, obviously, but it will either end up heavy or if trying to compete weight wise very thin and as you go wider and wider that effect will become more apparent.

I would suggest a nice well known tough rim like a Mavic 321/521 etc and some tyres with a decent side wall thickness.

andyl pretty much has it nailed.

High strength steel would allow you to go for very low wall thickness for your required section thickness, but local bending from the tyre bead and from impacts would be far worse.

If you were to build an aluminium rim of the same weight as the high strength steel rim, it would be stronger in an impact and easier to produce.

I suspect any steel rims will be significantly weaker than even a decent XC rim. It would be possible to extrude steel to make a box section rim, however why would you when aluminium is more suitable? If you start using high strength steels, you will progressively lose the ductility as well, so any ability to bend back will be reduced.

DH rims don't add that much mass - a very burly rim will be 600-700g. Just run them.

Thanks all. Looking at DT FR 570 pr Mavic EX 729 rims then; though hopefully I can get through the rest of the 'summer' with no more dings.

gaidong - Member
I just heard back from that Italian company:
...the rims are available at the price of Eu 11,39 + italian tax of 22% each
Weight around Kg.1,00"

Stainless steel Dunlop WO38 section 28" rim

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Steel is a heavier material, it's whether a lightweight structure could be built with it that is the question

I do have some lightweight steel wheels. My 1932 Sunbeam Road Racer wheels feel pretty similar to a modern wheel and it has steel rims and hub. I'll have to weigh it out of interest now - but I won't be dismantling it to get the rim weight. 🙂

I agree with the general opinion that a stiff alloy rim does the job, but it was worth the OPs time exploring the issue.

However I still suspect that there may be a place for a steel rim with a fat enough tyre.

I don't remember ever hearing a rim being hit on my fatbikes, and there's certainly no marks on them. Similarly with my 1x1 which is running 2.8" tyres on 40mm rims.

The steel would most likely spring back rather than ding if the rim was compliant enough at its edges (obviously it has to be stiff at the spoke perimeter), whereas the alloy used in rims usually deforms. The rim doesn't work on its own, the inflated tyre and rim constitutes the structure.

But the practicalities are that no one is making a suitable rim or is likely to.

You can bend the lip of an alu rim back with pliers, btw.

But perhaps not as far as would be required in the OP's pic. I can only suggest looking where he is going in future 🙂

[quote="molgrips"]You can bend the lip of an alu rim back with pliers, btw.Except you end up with a brittle/work hardened area with loads of little cracks......

Yeah but it'll carry on for a long time.. from experience.

However that was long enough ago that I was on rim brakes and it only had to last a limited time. I have yet to dent a rim with modern big tyres.

[quote=epicyclo ]The steel would most likely spring back rather than ding if the rim was compliant enough at its edges (obviously it has to be stiff at the spoke perimeter), whereas the alloy used in rims usually deforms.

Except that, as already explained above, for a given rim weight* the steel one will have thinner walls, hence will have lower bending strength and will ding at lower loads than the alu one. There's nothing particularly different about alu compared to steel in the way they spring back rather than deform - up to the yield point both will spring back, above the yield point both will deform. You just haven't ever seen a comparable steel rim subjected to the sort of loads which dings alu rims, and applications you might have seen steel used in aren't comparable.

*of course you can make a steel rim with similar cross section to an alu one, but then it will be a lot heavier and you'd be better off with a heavier alu rim with thicker cross section

andyl - Member

cynic-al
I doubt wall thickness would be an issue - it isn't on steel frames

yes it would and is.

...

Using a high strength steel alloy you could make a really thin wall and light wheel/frame/anything and it might also have suitable stiffness (read as nice and springy) but it would buckle as soon as you looked at it like an empty beer can.

It is exactly how we make aluminium aircraft - thin wall, high strength aluminium alloys. Wing skins in tension are incredibly thin and can take huge whole structure deflections but locally they are very easy to damage.

If you are building any steel bike rim down to a weight that competes with an aluminium one it will have to have thin walls and stones WILL dent them. Deep section aluminium MTB rims are bad enough for stone dents. Remember stiffness is non-linear with thickness unlike modulus and it is this local stiffness that resists damage from objects and those local areas of damage end up affecting the stability of the whole structure and can lead to buckling as the load is no longer being carried along the structure as it was designed.

You can make a MTB rim out of steel, obviously, but it will either end up heavy or if trying to compete weight wise very thin and as you go wider and wider that effect will become more apparent.

How do you know this?

Why do my ultra thin steel tubed frames not dent as easily as you suggest? (A rim could easily use a curved profile and shallow wall to get the strength from those).

A rim isn't a frame al - a frame has tubes which are inherently stronger than a cantilever section - the hoop strength means they'll even resist localised denting better. A curved profile on its own won't give you that if one end is unsupported - it's the continuous fully supported nature of a tube which results in the strength.

Oh and a thin wall steel frame will still dent easier than an alu one with thicker walls all things being equal - presumably with your frames you simply haven't subjected them to enough point loading (the sort of thing you won't get in normal riding).

It's basic structures and materials science.

@epicyclo, can you still get rims like that? I wasn't bothered by the idea of the Italian rim being 1kg; I'd want stainless rather than chromed.

@all, When I have shallow dents on rims I use a pair of STEEL motorbike tyre levers to spread the force when I use a pair molgrips to straighten. It works. That is it works and work hardens the aluminium, with lots of micro stress fractures. As I said in my very first post, I wasn't looking for light, I was looking for durable and repairable.

As for the ding in that Grail, a pedestrian was blocking the entrance to the cycleway (fair enough) and instead of slowing down I tried to jump the kerb at over 30 km/h... Agreed that no rim would survive that!

gaidong - Member
@epicyclo, can you still get rims like that? I wasn't bothered by the idea of the Italian rim being 1kg; I'd want stainless rather than chromed.

That rim is about 60 years old, and you'll occasionally see them on eBay, but never cheap. And it's a 635mm, so no good for mtb tyres.

[url= http://www.dutchbikebits.com/traditional-bicycle-wheel-rims ]Dutch Bike Bits have the traditional sizes in SS.[/url]

[url= http://www.kadindia.com/company_kadsteel_rolling.html ]And a mill that rolls SS rims in India[/url]

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