Rotor RHawk Cranks - First Look

Mar 14, 2017
by Paul Aston  



Last week, I headed to Madrid, Spain; the land of bullfighting, competitive coffee, and Rotor Bike Components. Rotor has been involved in the cycling scene for over twenty years - a small brand that has deep roots in road bikes, mostly known for their oval chainrings and previously, for their wild-looking 'Rotor System' road bikes. Rotor has dedicated its existence to create extra-efficient pedaling systems to work with Man's funny legs, appendages that arguably, were never designed to pedal a bicycle in perfect circles.

Rotor expanded into cross-country mountain biking, and now it is developing drivetrain components that cater to the more extreme end of the mountain bike industry. They have employed two legends: Cedric Gracia and Brett Tippie to assist their efforts, and Rotor's first major development in their new range is the RHawk crankset, made entirely in Madrid, and CNC-machined from 7055 aluminum alloy.
Rotor RHawk Details
• Intended use: all-mountain / enduro / downhill
• Modular design
• Extruded and CNC machined 7055 alloy
• OCP Q-Ring adjustment
• Sizes: 165/170/175mm
• 30mm axle
• Silicone boots in seven colors
• Q-Factor: 164 mm / 170mm boost / 179mm DH
• Chainline: 50mm / 53mm boost / 57.5 DH
• Compatibility: BBRight / BB30 / PressFit30 / BSA
• Made in Spain
• Weight: 175mm, with silicone boots and boost axle, 665g (claimed)
• MSRP: $345 USD (cranks, axle, BB, boots and chainring)
www.rotorbike.com




Rotor Hawk Cranks


Construction

Rotor are not trying to re-invent the wheel here with the RHawk, and certainly not trying to lumber us with any new standards In fact, one of the biggest challenges to the small brand has been keeping up with the ever-changing list of slightly different fixation points. To help tackle this, the RHawk crankset is completely modular. All parts should be available separately, which is good news for the consumer. For example: if you buy a new frame with a different width bottom bracket, you can simply buy a new axle. Trash any parts in a crash and you can buy singular replacements.

RHawk cranks are machined in-house in Madrid at EDR Engineering, which was previously subcontracted to machine on Rotor's behalf. EDR was recently acquired by Rotor and is only 100 meters from its HQ - a huge help for engineers who now can simply stroll across the street to check out their latest creations as they are born.

The standout feature of the RHawk is the way the crank arms are hollowed out internally with three full-length bores that correspond to machined channels on the outside of the crank to maximumize weight reduction. 7055 alloy is used, and Rotor say it has the same mechanical properties as the more common 7075 series, but with better fatigue properties. Each extrusion goes through an ultrasonic check by the supplier to discover and eliminate any defects found in the raw material.

Rotor Hawk Cranks
This cut-away shows the large bore holes that run the full length of the crankarms.

Rotor Hawk Cranks
Two holes bored from the pedal end of the arms are sealed by the plastic guards

Rotor Hawk Cranks
Rotor Hawk Cranks


RHawk's wide architecture means that Rotor can shorten the overall length of the crank arm by removing material on the terra-firma side of the pedal axle, which should be great news for those who suffer rock strikes. Even though the cranks are aluminum, there's added plastic protection - a welcome touch that wards off heel rub and rock strikes for today's low bottom bracket society. And, for the color-coding crowd, there are seven shades to choose from.


Q-Rings and OCP

All Rotor's oval Q-Rings feature varying degrees of adjustment and, thanks to their patents, they are the only brand to offer this. Rotor says that to truly benefit from the smooth power delivery advantage of oval rings, the riders must be able to find the "sweet spot" that works with their bodies' and bikes' geometry. Riding disciplines also play a role in this choice. Triathletes, for example, will be in a completely different position compared to that of a mountain biker when pushing the pedals. Traditional Rotor Q-Rings simply use multiple bolt positions on the chainring and spider, but with the overwhelming adoption of single chainrings for mountain bikes, Rotor created a new spline system that allows for clean-looking, direct-mount rings

The axles and chainrings are laser etched to make installation fool-proof and to accurately mark the degrees of adjustment of the spline interface. Rotor also make aftermarket rings to suit most crank types on the market, although those do not have the spline option to adjust the crank timing.


Rotor Hawk Cranks
Laser-etching on the axle should mean hassle free installation.
Rotor Hawk Cranks
The rings are also etched to indicate the apex of the oval.

Rotor Hawk Cranks
10% ovality

Rotor's wide/narrow style mountain bike Q-Rings have a 10% oval. There are many opinions floating about on how oval an oval ring should be, but Rotor believes 10% is the best option for the masses, and particularly for mountain biking. For certain, with its European aluminum construction, heavy hitting appearance, and range of options and adjustment, the RHawk is set to compete with custom crank makers like Hope. We have an RHawk crankset in the post to put through its paces, so keep an eye open for a long-term review.


Rotor Hawk Cranks


Must Read This Week

74 Comments

  • + 55
 I am happy to ride for Rotor. I have been testing the RHawk 170mm cranks on the north shore and just spent a week shooting on some technical trails in Laguna Beach, CA on them. I have not dropped a chain once and sent some kinda flat landing rock drops on my new bike...not a hint of crank or BB flex and feeling great. Stoked!
  • + 5
 How is the new bike? When do we get to know what it is?
  • + 11
 @tuboy95: who is the most local company to laguna? Intense?
  • + 4
 @tuboy95: He's now riding for Porsche.
  • + 2
 @DirtyRider13: apparently YT is.
  • + 34
 i like the modular idea. I would like to see the cranks offered in different alloy colors like raceface.
  • - 44
flag moutnbiker (Mar 14, 2017 at 8:18) (Below Threshold)
 If its that big of a deal for you, you could always get them powder coated any color you like.
  • + 28
 @moutnbiker: powder coating and anodizing are two completely different processes with equally different looks to the finished product.
  • + 13
 Modular designs are great, especially when they are adaptable to new standards. That's my favorite part about my Hope Hubs. I can use them on my qr bike, my 12x142 bike, and when I inevitably end up with boost spacing the hubs will work with that too.
  • + 12
 @pacificnorthwet: boost only with spacers though which defeats one of the purposes of boost
  • + 2
 @pacificnorthwet: Pretty sure Hope 12x142 hubs can't be converted to 12x148
  • + 8
 @willbikeleeds: lindarets has boost kits available and they are nice and work well..I'm running hope pro 2 on boost spaced 2016 trek fuel ex 9.9 and it's all good!
  • + 0
 @TheElectricGhost @bohns1: My bad, although that solves a lot of problems for me now. Cheers guys Smile
  • + 1
 @rrsport: Check out D.FENDER's "un-boost kit"
  • + 2
 @therealtylerdurden: no kidding, PC is a lot easier and something you can do at home. You can do ANO at home too but take a hell of a lot more equipment and know how.
  • + 1
 @pacificnorthwet: will it? I thought the brake disks run a different spacing on boost?
  • + 1
 @twellsie: You need to use a kit like the Boostinator. The rear kit comes with a spacer for the rotor. No need for the front hub though. But the wheels do need re-dishing.
  • + 1
 @twellsie: I thought Hope was going to come out with their own adapter kit (maybe they still will), but either way their are a few aftermarket options available. It's nice having the option to keep old stuff running.
  • + 1
 @pacificnorthwet: They do sell a front boost adapter, just not a rear. I'm not sure that they'll bother tbh.
  • + 14
 Rotor is an old prestigious brand. Agree about cnc. Good they check for defects but... is amazing how much more strength and weight reduction they'd get from 3d forging.
  • + 4
 @captaingrumpy totally agree - one would surmise that by fleecing roadies for years with CNC'd cranks and ovalized rings that they could just about capitalize a set of sequential forging dies, and make mtb cranks for the riders who really need that strength! But then they'd be Saints.
  • + 9
 Drop forging gives you a superior grain structure but requires a larger initial investment and less flexibility than CNC. So what's economical depends on the number of products you plan to sell. If you plan to sell only small numbers, you may prefer CNC whereas if you plan to sell huge numbers it will cheaper to design for mass production techniques (casting, forging etc.). But Rotor is clever here, they don't machine from a solid billet. Instead (if I understand correctly) they machine from an extrusion, similar to how quite some (VP and Wellgo) mountainbike pedals are made. And extrusion gives you a decent grain structure as well, comparable to hot forging. That said, it is hard to beat Shimano. They sell in such huge numbers that it is worth investing in the dies. If money were no object, I'd invest in Middleburn but I can't even tell if they're actually better than Shimano.

The advantage of forging isn't necessarily in strength though, but fatigue. Aluminium is subject to fatigue. Always, unlike steel and titanium which have a fatigue limit (below which occurs no fatigue). And during the crack growth phase of the fatigue cycle the crack grows between the grains. A production technique like forging gives you a flat grain structure parallel to the surface (due to the forces applied to that surface during production) so (fatigue) cracks also grow parallel to the surface. Which means that it is more likely to just chip than to break straight through. So in discussions/marketing where people say "oh no this is really great because we machine from a solid billet of material with an ultimate tensile load of..." this is not what it is all about. Unless your name is Sam Hill, fatigue is the dominant failure mode for your cranks and forging is always going to give you the best product. But the approach Rotor took here to machine an extrusion is clever as it gives them flexibility without having to deliver large quantities. Aluminium extrusion is relatively cheap.
  • + 1
 @vinay: thanks for the educated answer!
I'd be curious to know what the original extrusion looks like for Rotor cranks - from the final product I can't see the extrusion being anything else besides a solid rectangle, no internal mandrels etc.
Thomson build their seatposts the same way, extrude then machine away everything but the lower clamp area, and that definitely makes a solid product.
  • + 10
 I like alu, and modular/interchangeability, and weird shaped rings in some cases. Probably too spendy for me but maybe the price will come down. If you don't like the price or any of the other things, hey - don't buy one. Looks pretty nicely thought out though.
  • + 7
 I would imagine Gracia and Tippie more than put these through their paces. I'd be ok with getting a pair.
  • + 4
 Yes that's how it works in component marketing... job well done Rotor!
  • + 6
 Hmm don't see the Praxis offering the flexible timing of the oval, so how you consider the two equals I'm not exactly sure.
Also the Cadet is 1/2 lb heavier.
  • + 7
 What the f*ck is competitive coffee??
  • + 2
 The look kind of reminds me of the Double Barrel cranks by Caramba. My friend and I were both excited about them. We both bought in thinking they were for aggressive riding. We both snapped the left arm within a month of each other. These do look to be stronger and I'll assume that forging has made leaps in MTB since the days of the Double Barrel cranks arms. The idea behind this crank is a good one, but to me, the cost is not worth it. I will probably see these on a wild Dentist bike!
  • + 7
 Tough crowd today. (-:
  • + 2
 "First oval chainring"???? Was the Shimano Bio-Pace not the same concept?? 30 years ago??
Not that I run them or really give a crap, other than when someone says the "First of its kind" or "Never before has this been produced" it rubs me a bit...lol No hatin tho...just clairifcation....
  • + 3
 Bio pace destroy knees and give power, rotor is all about saving knees and evening out the power production for better traction.
  • + 4
 I've often wondered if these cranks with protective rubber simply wear out the sides of your shoes faster...
  • + 2
 Iv been running these cranks for a month and that are amazing. Also the chain ring works real well and clears the welsh mud slop and keeps running smooth. Best set up iv ever run by far
  • + 1
 My brother made me try a set of Powercranks and I was able to appreciate pedaling on crank arms as short as 152mm!!
(Note: I am 183cm tall)
Being able to buy the arms separately from the cranks will have me drop a friendly email to Rotor very soon!
  • + 4
 I like 'em. Available online?
  • + 2
 So they brought back Caramba Double Barrel cranks from the 90's and made them modular.....
www.retrobike.co.uk/forum/download/file.php?id=144150
  • + 1
 Tenuous.
  • + 0
 At 600g, I don't see why someone wouldn't just run XT (or SLX) cranks. I doubt these are in any measurable way better (stiffness, durability, etc).

A modular design is likely to take as much as it gives; sure you can upgrade or replace parts, but the interfaces are potential failure points.

I suppose some dentists who think they're rad at the bike park might dig 'em....
  • + 1
 Amazing looking concept, up there with carbon cranks, the next revolution in cranks in my opinion. WOW made from allow and hollowed out with protective boots, here we have a true carbon contender that uses alloy.
  • + 2
 I wore shorts that pistachio green color to a cubbies game one time in Chicago... Man did I get made fun of! Still not sure why.
  • + 1
 Best of luck to them and best of luck to us the more manufacturers the more competition the better the quality the lower the price
  • + 1
 Very cool design, although I was a little surprised to see that they're still heavier than the RaceFace Turbine Cinch cranks. Does 665g include a BB or something?
  • + 2
 Do we need another proprietary chainring interface
  • + 16
 If you don't want the oval with the ability to time the ring- plenty of other cranks out there. At least this is something different.
  • + 0
 @TheOriginalTwoTone: I also find playing with the clocking of the oval chainring a very interesting feature. Construction could be a little better, and why put grooves on the outside really? Digging more material from the inside would certainly have the same effect (weight vs stiffness) without collecting mud. Maybe it's not an issue in Madrid?
  • + 4
 @EnduroManiac: look at the profile. You can only remove material in so many ways.

If you look at the cut away you can see the only other place left to remove material and maintain strength is in between the hollowed out tubes. Doing it on both sides reduces the most amount of weight.

Look at Hope cranks, they do the same thing.
  • + 1
 @EnduroManiac:
They might not have the manufacturing capabilities, my understanding is that hollow forging cranks isn't easy.
  • + 1
 @EnduroManiac:
"Digging more material from the inside would certainly have the same effect (weight vs stiffness) "

True, however that would be MUCH more difficult to achieve using conventional machining methods. Drilling a single hole with a depth that is 15-20x diameter is much easier than milling a pocket with a depth that is 15-20x the minimum pocket width.
  • + 1
 I have been using Q-Rings (ex Ebay) for a while on old X9 Cranks and they have worn well so far with over 1000 kms on them.
  • + 2
 no new standards...... cept the ring mounting....
  • + 1
 Pricey for a 2D CNC product. Better available at better price point..Praxis Cadet for example.
  • + 1
 Shimano Saint is all I need.
  • + 1
 I never wear boots. I sure do love your Silicone boots
  • + 1
 Where is the fooking door !!
  • + 1
 Cool concept but those crank arms a atrocious!!
  • - 2
 I agree ..Race face next SL all day long! That or Turbines meng!
  • + 1
 No one else is excited about the integrated safety compartments?
  • + 0
 The building looks empty! ......hello is anybody in there?
  • + 0
 Do they make an upper chain guide that bobs up and down Smile
  • + 1
 Xtr
  • + 1
 I like the boots.
  • - 2
 Haha, that "first name in oval chainrings" cracked me up. That's like "first name in non-driveside spokes"!
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