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

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.

Good find. I didn’t know there was anyone making that size in that section these days. I might get a set so I can use decent tyres on my old British roadster.

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.

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″

Weight seems about right for a 28″ rim

Stainless steel Dunlop WO38 section 28″ rim

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 1×1 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 🙂

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.

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.[/quote]

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.

Dutch Bike Bits have the traditional sizes in SS.

And a mill that rolls SS rims in India