M5 road cranks 238 grams, bottom bracket 120 grams

[1centaur]

I'd be happy enough with significantly lighter and equally rigid.

[Chocolate Milk]

Really? My 175mm CQP cranks are 600g with BB and single 50t Campag Record ring, stiff as I need (my other bike has Record Pista, and I can't feel any difference) and have been on my bike for 15 years. In the intervening 15 years, Campag have managed to come down to within 50g of what a small shop in San Luis Obispo could do back then for about $1500 in 2008 dollars. M5 propose a weight of about 500g for the complete set. Over the same period, we've happily accepted that a superlight frame has come down from ~1500g to under 900g

That's kind of my point. You're discussing changes over 15 years. Do you have any idea how many advancements in materials, material prepping, tooling, manufacturing, etc. there have been in 15 years? Over 15 years it's perfectly reasonable to see a 1500 gram frame morph into a 795g one. But that's not the case here. The latest tech from Campy, SRAM, Shimano and FSA is saying "This is what a top level lightweight crank weighs today based on available materials/methods." And M5, based on no new advancements in material or technique, is claiming they can make a safe crank for half the weight. I don't buy it. What, the other folks in the industry don't have a vested interest in staying competitive weight-wise? It's preposterous.

Do you apply the same argument to M5 brakes, which are 2/3 the weight of Record skeletons? The cranks come from exactly the same design approach, the same FEA computation and the same CNC manufacturing process as the brakes.

The technology exists to make safe brakes that are significantly lighter than the current big 3's top line offerings. It just costs a lot. And my earlier claim that if safe 330g cranksets were possible the big 3 would have 500g cranksets applies here perfectly. SRAM red is what, 30-35g heavier than Negative G's?...

Campag/Shimano/SRAM are compromised by the need to make thousands of examples of any component quickly and cheaply; they are different from M5 in the way that Lexus is different from Lola.

Giant corporations and tiny boutique builders compete in the high-end market in different ways. While you are correct that the structure of a company like Shimano makes it unable to compete with M5 in attention to detail and time spent on individual components (hours of hand-machining, etc.) it does have a lot more money to throw around in R & D than M5, or other smaller specialty manufacturers. The end result seems to be a narrow margin of better weight and performance coming from the boutique companies, mostly because while technology and R & D trickles down, plain hard work and attention to detail does not. So companies like M5 actually benefit from the research of companies like Shimano. The end result is a narrow margin of performance. Not something koo koo bananas like a 330g crankset that's stiffer and stronger than DA.

The M5 crank may or may not be any good, but it doesn't seem impossible using current technology to make a crank which is 75% of the weight of Record and still adequately stiff and strong.

330g is less than half the weight of current Record, not 75%. No, I don't think it's possible to make a safe, reliable, rigid crankset at that weight for a 1,500 dollar price point with current technologies and manufacturing techniques.

A crank cannot be made out of any grade of aluminum and be significantly lighter and significantly more rigid at the same time than Dura Ace... for any price. I spent over a year, thousands of dollars and tested over 12 designs and managed only marginal gains... Dura Ace is the best bang for the buck at the moment IMO.

See? This guy agrees. And he should know...

[kinky_cowboy]

Really? My 175mm CQP cranks are 600g with BB and single 50t Campag Record ring, stiff as I need (my other bike has Record Pista, and I can't feel any difference) and have been on my bike for 15 years. In the intervening 15 years, Campag have managed to come down to within 50g of what a small shop in San Luis Obispo could do back then for about $1500 in 2008 dollars. M5 propose a weight of about 500g for the complete set. Over the same period, we've happily accepted that a superlight frame has come down from ~1500g to under 900g

That's kind of my point. You're discussing changes over 15 years. Do you have any idea how many advancements in materials, material prepping, tooling, manufacturing, etc. there have been in 15 years? Over 15 years it's perfectly reasonable to see a 1500 gram frame morph into a 795g one.

I think you miss my point; if CQP could, 15 years ago, make a crankset which is still lighter than a 2008 Campag Record, and yet strong enough for me to use it for those 15 years and stiff enough that I can't tell the difference compared with a Record Pista, the frame argument suggests that the cranks (with BB and 1 ring) should now be down to ~350g if a manufacturer exploited all those technological advancements and was trying as hard to satisfy price-insensitive weight weenies as CQP was in 1992.

I'm not saying the M5 is this crank, or even that carving from Aluminium alloy is the right way to do it, but it's bold to assert that a chainset can't be made at the M5 target weight of about 450g for cranks, BB and 1 ring.

The problem with cranks is to get enough torsional stiffness (resistance to twisting around the long axis of the crank arm) into the narrow gap between the BB shell and the preferred location of the pedal spindle mount. CQP solved this the really obvious way by filling up the space with a tapered titanium tube of circular cross section, but wasted quite a bit of material by making the cranks a conventional 3-piece square taper set up with a solid titanium BB spindle. They were about 10 years ahead of the big guys in managing to get the faces of the bearing cartridges 75mm apart in a conventional 68mm BB shell, and combined with a 139mm Q factor there's very little leverage available to bend anything sideways.

If I were setting out to make a 450g chainset, I'd probably start with the idea of titanium tubes and then use more advanced processes than just welding drawn tubes to machined bosses, such as this http://tinyurl.com/25uw2k similar to the way Rolls Royce makes Trent 900 fan blades. As these 1.2m long blades are probably less than $50,000 each (at 50k, the complete fan would account for 1/8th of the total engine cost), I'd hope the process would scale to make a 0.17m crank arm under $500 each I have a nasty feeling that getting the unit cost down to $500 per arm might involve volumes in excess of the total market for $1500 chainsets...

Campag/Shimano/SRAM aren't saying that 700g is the lowest possible weight for a chainset, they're saying it's the weight of one mass produced to retail at ~$500. They're competing against one another on weight, but only insofar as that also allows them to be price competitive to sell in volume and make good profits; the market seems to indicate that there is good money to be made making thousands of $500 chainsets, not much to be made from making a couple of hundred $1500 sets, and even less a few dozen at $5000. In that sense, I agree with you; the 450g chainset might not be economically viable at $1500, or even at all, using current technology. We'll have the answer to that question when, or if, production units of the M5 have been in service for a while.

[FreaK]

hah, first good argument in this thread!

kinky_cowboy, i salute you.

I'll stop there or i might start making un-friends again.

[wally318]

So you don't think that it's possible to make a cost effective 330 gram crank? Well actually their claim is 358 gram incl. the BB. Stay tuned for my version of a sub 330 gram crank/BB. It's not for production. It's a 1-off prototype to be used on a ultralight hillclimb bike project. It is STIFF. And it didn't cost anywhere near 1500.00 .I won't say anymore right now. I'll post pics when it's completed, hopefully in the next couple weeks. No stress testing req'd.

[Samu Ilonen]

Newer mind.

[pyf]

A crank cannot be made out of any grade of aluminum and be significantly lighter and significantly more rigid at the same time than Dura Ace... for any price. I spent over a year, thousands of dollars and tested over 12 designs and managed only marginal gains... Dura Ace is the best bang for the buck at the moment IMO.

... that's just my 2 cent report,
Ted Ciamillo

Just wanted to congratulate your honnesty !!!
It's not so often that we see a manufacturer accepting that he couldn't do better than what another has already done. I really appreciate this !

As far as aluminium is concerned, I think Shimano has access to the some of the best technologies at a reasonnable price thanks to how big they are. That's great for the custommers but makes it difficult for other to beat them when it comes to aluminium or... if a small guy wants to beat Shimano at this game the retail price of the crankset will be insane and nobody wants to pay a lot (I'm not saying this is right !!!) for aluminium.

aluminium lighter than Shimano like FRM or Extralite = not as stiff.
Cannondale Hollowgram = awsome... but can't be mounted on any frame like a Shimano does.
Lighter than Shimano and as stiff = expensive carbon crankset.

Thanks again Ted !

[FreaK]

Ok, i said i wouldn't but suddenly i can't help myself. With the engineering philosophy they were approaching the problem from there was no way it it would happen. Zero g i'm sorry, but i don't know what you were thinking.
I'll now officially shut up on this topic as i don't generally store a firesuit in the coatcheck here at weightweenies. Mostly that's for weight reasons, but partly i just can't be bothered.

[jipperd]

A small update, I was asked to get some information about the M5 crankset. Since I live in Holland, it's easy for me to contact them so here is some information:

A couple of days ago I contacted Bram (owner of M5-ligfietsen) about the availability of there very lightweight aluminium crankset. Bram replied, answering two questions. The first was the availability of there clincher rims, they should be available in a short period of time. Now on the more important question, for this tread, when is the crankset going to be on the market. Bram didn’t have a ‘exact estimation’ of the availability but is isn’t going to be there any time soon. The crankset is still going to hit the market but when, only Bram knows, and actually even he doesn’t...... so

[Johnny_Yutah]

I believe that Bram will soon release his IMAGINARY crank...

[HammerTime2]

I believe that Bram will soon release his IMAGINARY crank...

If you rotate it by 90 degrees, will it become Real?

[Skillgannon]

I believe that Bram will soon release his IMAGINARY crank...

If you rotate it by 90 degrees, will it become Real?

You could square it as well...

[ScienceIsCool]

...and then it would be an anti-crank? Every pedal stroke forward would move you backwards?

John "damn I'm a geek" Swanson

[XL_Carbon]

It's nice reading light humor on occasion especially when it's quite clever.

But seriously, they may someday appear even if they have disappeared from memory.

[mythical]

Amusing thread indeed.

I happen to speak with Bram the other day. He seemed more interested in the progress on my crankset project so I couldn't ask him about his when he received another call, but... I'm gonna call him soon and ask for an update.

Meanwhile, I dare to say that a safe sub-350g (e.g. CEN/EN14781 compliant) crankset including chainrings isn't impossible. Who knows in the near future...