Video: Making Hope Cranks

Jan 27, 2015
by Hope Technology  
 
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Hope Factory Barnoldswick

Designed. Tested. Manufactured. Seven years in the making, the versatile, do-it all Hope Crank has finally hit the shelves.

You may have seen various versions of the cranks over the past few years on our staff and team bikes. We spent the time testing, tweaking and redesigning them to ensure they’re as good as they can be.

Hope Tech Factory
Hope Factory Barnoldswick

The final crank design features a unique expanding spline axle/arm interface (pat pending). Previously, cranks with splines often used a taper to ensure a snug fit. These cranks worked fine the first time they were fitted to the axle, but once they’d been taken off and on a few times, the spline became worn, so they’d suffer from the inevitable movement and annoying creak.

Hope Tech Factory

To solve this problem we settled on a unique expanding spline. The cranks are pulled onto a spline, then a tapered plug is fitted inside the axle which can be tightened up each time the arm is refitted – giving a perfect fit every time.

Hope Tech Factory

Added to this we CNC machine the arms from forgings which gives them immense stiffness and strength. The arms also have a splined mounting for spiders and direct mount sprockets giving excellent versatility. The spiders are available in either single (104 BCD) or double (64/104 BCD) ring configuration.

Hope Tech Factory
Hope Cranks - anodising

The cranks use a 30mm axle and are compatible with the majority of bottom bracket systems via our expanded range of bottom brackets.

Hope Cranks Grim up North

Specification:
Material – Forged and CNC machined 7000 series aluminium alloy crank arms
Length – 165, 170 and 175mm
Q-Factor – 167mm
Chainline – 49mm
Axle Diameter – 30mm
Expanding spline crank arm/axle interface (pat pending)
3-piece construction
Versatile Spline mount for chainring/spider
Chainring mounting: -Spiderless Retainer chainrings 26T to 36T
-Spider Single 104BCD and Double 64/104BCD
Colours: Initially black, with red, blue, silver, gunsmoke and purple following in March
Weight: 641g (arms, axle and 34t spiderless ring)
Prices: – Arms, Axle and Spider £245/€300/$400
Arms and Axle £215/€265/$350
Spider £40/€50/$65
Spiderless Retainer Chainring £55/€68/$90

www.hopetech.com @hopetech

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106 Comments

  • + 98
 This video gives me such an engineering boner
  • + 3
 Gave me a serious case of the jizz
  • + 3
 I want to work there now, haha.
  • + 8
 Professor farnsworth from futurama would call it a "raging brainer"
  • + 1
 Made me think I'm so glad I got out of it see that box of billets that dude had to machine ughh such a shit under paid job.
  • + 3
 I wonder if you can do a uni placement there...
  • + 1
 So awesome that they're manufacturing these in house
  • + 1
 Hey thunder13, Are you using the threaded cockring at 00.37?
  • + 2
 Ha! petepantera beat me to it! Dat SolidWorks robot reader Tho! Off the hook.
  • + 53
 I'm really pretty sold on Hope stuff. I spend quite a bit of money between them and Thompson, but the quality and longevity are amazing.
  • + 19
 You get what you pay for.. especially with Hope Smile
  • + 22
 I would hope you get what you pay for! Sorry..
  • + 56
 I CNC what you did there.
  • - 19
flag zephxiii (Jan 27, 2015 at 6:38) (Below Threshold)
 I hope we don't get any pun haters! DERP
  • + 26
 I'm laughing so hard it hurts my spline.
  • + 5
 I hope they come with some Advil becuase that fumbly install process is sure to cause alot of headaches.
  • + 19
 don't get all cranky on us.
  • - 39
flag Rocky-Urban (Jan 27, 2015 at 8:01) (Below Threshold)
 Is it fair to put the Made in UK label on a product built by a Japanese made precision milling machine? Although most products are built using Japanese and German made machinery. I guess when you see something made in Japan then it can really be regarded as truly being built in Japan.
  • + 13
 Should not have watched it, now I want one.
  • - 10
flag keatonmtb (Jan 27, 2015 at 8:38) (Below Threshold)
 You better HOPE that after all that work it dosent start CRANKING up
  • + 5
 Im really hopeful my wife will let me get these
  • + 16
 nice video and loving the Yorkshire-french style accent - lol - loved seeing the factory and gives hope for the future of manufacturing here - i would love to support them, really would but no way i can justify that price - good luck with the new gear but its pricey, but that to be expected when its truly "made in the UK"
  • + 1
 Just what I was thinking! Frenchshire? Yorkrench?
  • + 2
 No worse insult could be coined. Not Yorkshire. Lancashire.
  • + 1
 dammit and i know that too as i have family there - brain fart moment - sorry Mutly .. either way its a kick-ass accent Smile
  • + 11
 Nice but I'm still not ready to give up my raceface cranks that are a fraction of the cost, lighter, and have an available colour way.
  • + 2
 you mean... better?
  • + 3
 yes. exactly.
  • + 10
 Did anyone else notice the "threaded cockring" at 00:39 ?
  • + 2
 I was just gonna post that but you beat me to it hahaha
  • - 1
 That's a special part for hope fanboys
  • + 0
 I hate when my L's look like a C.
  • + 6
 Hope have priced this rather strangely? Or is it just me? So you have to buy arms axle and spider for £245, then on top of that a bottom bracket, and a narrow wide chainring. OK Hope are a great company and I'm sure these cranks will still be strong after 10 years of abuse, but for nearest of £290 (hope cranks, spider, bb, chainring) you could easily buy yourself 2 complete sets of shimano xt cranks with lots of money spare. Maybe I'm missing the point.
  • + 9
 Note all of the super expensive machinery used in the manufacture of these crank arms to what I'm sure are industry leading specifications and tolerances. That manufacturing process isn't cheap and they're made in GB. I don't know where Shimano are made, Malaysia maybe. Labour is cheap and they probably 'crank' out way more volume.
  • + 4
 Except that Shimano XT cranks are butt-ugly. But who am I to tell you how to spend your money.
  • - 2
 it's not even like they are bling either. people will buy for the name only with these. I'd not even consider these over anything else in the market. about £100 over priced.
  • + 6
 well considering how expensive other cranks are i think these are pretty reasonably priced for their quality. (ahem RF sixc)
  • + 9
 Crank arms are made of not just "7000 series" but precisely of alloy 7075, (guess T6). The man on video told this clearly.
There is a huge difference between 7005 and 7075 while both are of 7000 series.
The 7005 hardness is about 85-90MPa
The hardness of 7075T6 is 150MPa, 7050T6 - 147MPa
So it is just great!

And the other man tolds about 0.001mm repeating precision of their CNC machines.
That's just exceptionally great!

But the price....HOPE it will lower.
I'm pretty sure their machines already returned the costs spent on them long ago.

The 7055T6 is of 198..202MPa.
And it is what the RF Diabolus crank arms are made of (OptimAL is 7055T6 really)
So I personally will be fine for many years further on them, nevermind what some people say on the net about interface issues - mine are fine on 2 bikes under 85kg of my body pumping and jumping them badly.
  • + 2
 SIXC is lighter though
  • + 6
 You're also buying Hopes AMAZING customer service. Also , these cranks WILL last a lifetime. Barring any accidental damage I reckon these will be the last crankset you ever buy. Now weigh that up against say 10 years of XT crank sets , I've seen XT's wear thin an snap. An they're actually cheaper in the longrun
  • + 4
 I don't think that hardness is given in MPa, tensile strength is. for hardness there are HB HV HR scales depend on the method of measurement.
  • + 4
 @bikecustomizer
Fatigue life, which is how cranks typically fail unless you are a beast, is mainly dependent on stress amplitude, mean stress, ultimate tensile strength, and fatigue limit. There is a relation between hardness and UTS, but it isn't 100% concrete. There are also plenty of processes that can be done to increase fatigue life such as peening.

And as owls said, hardness is not measured in MPa.
  • + 2
 @nojilla my STX-RC cranks were 19 years old before I changed to XT as I was swapping bike. I don't need to spend almost £300 on a crank.
  • + 1
 @bholton: I think all XTR, XT, and SLX are manufactured in Japan. All the Deore stuff I've seen was stamped Malaysia.
  • + 2
 @bholton

Shimano make:

-Their upper end cranksets like XT / Saint and Ultegra / Dura Ace in their Japanese plant

-Their mid range cranksets like SLX and Tiagra (road) are made in their Malaysian plant

-Their low end cranksets like Tourney and entry level non groupset pieces like FC-171 are made in their Chinese plant
  • + 1
 @owls, taquitos
en.wikipedia.org/wiki/Brinell_scale
Brinell hardness is sometimes quoted in megapascals, the Brinell hardness number is multiplied by the acceleration due to gravity, 9.81 m/s2, to convert it to megapascals. The BHN can be converted into the ultimate tensile strength (UTS), although the relationship is dependent on the material, and therefore determined empirically.

And here the useful links:
asm.matweb.com/search/SpecificMaterial.asp?bassnum=MA7075T6
asm.matweb.com/search/SpecificMaterial.asp?bassnum=MA7050T735
asm.matweb.com/search/SpecificMaterial.asp?bassnum=MA6061T6
Compare and see.
Also I have the datasheet for 7055T6, which is yet more better.

I didn't say any word about the relation beetween UTS and hardness, did I ?
You're right!
But it is obvious that hardness could be used as kinda indicator parameter(one of several) to compare and choose the materials.
Also the modulus of elasticity.
The metall with higher hardness also(as a rule) have higher UTS, Tensile Yield Strength, modulus, fatigue strength.
All of the mechanical params depend on inherent structure.
There are many treatment processes used to improve the params by changing an inherent structure of metal(or other material).

Correct me if I'm wrong but the cranksets with so burly arms have their bottleneck in an interfaces.
The interfaces to the axle and the pedals is how cranks are typically fail unless you are a realy BIG BEAST to broke the crank arm itself.
So, the hardness is of high important when the many small alloy splines touch the steel splines at the steel axle and you badly push the crank arm which is a lever. Imagine what a high stress that little splines cary on!
It is the same thing as with rear hub's alloy freehub to steel cogs interface.
Cromo steel piece will deform (chew-in or other way) the alloy piece FAR EARLIER BEFORE YOU GET TO THE FATIGUE LIFE END, because it is harder. It should be something to undertake against it.
  • + 1
 Noone will argue against 7075T6 is much better than 7005 (besides welding) but both of them are of 7000 series.
I just mean that "7000 series alloy" words are have no sense: one can't get a real clue from it.
I can't accept a "bla bla" without any bit of measure.
  • + 2
 The correct units are not really MPa because things such as BHN don't quantify how much a material will resist indentation in different. Notice data sheets rarely give actual units for hardness. It's main function in the engineering world is to compare materials. As I said before, it has a correlation to other properties, but it is not well defined correlation and it is sometimes broken. It still can be used as an estimate, but it's just that, an estimate.

Modulus of elasticity and hardness are just the tip of the iceberg and have far less to do with when a component will break than you might think. Modulus of elasticity (aka Young's modulus) is d(stress)/d(strain) between strain=0 and strain=yeild. You could have a young's modulus that is super low and still have a high yield strength... it just means you get a lot of elastic deformation, which isn't necessarily a bad thing.

Long story short, you can't look up spec sheets and read a wikipedia article or two and be an expert. Material is only a small portion of the design process. The cross sectional area of your crank plays a huge role in how it feels.

Also, 7000 series means Young's modulus is 72 GPa.
  • + 1
 Clearly of course it is for comparing purposes.
Actuall objects may be made different by defined treatments but not too much.
3D forging and heat treatment are usual.

Well I don't want to write same again..but:
The metall with higher hardness also(as a rule) have higher UTS, Tensile Yield Strength, modulus, fatigue strength.
All of the mechanical params depend on inherent structure, some of them can corelate to each other.
There are many treatment processes used to improve the params by changing an inherent structure of metal(or other material).

ESTIMATE - that what I did using that info.

>You could have a young's modulus that is super low and still have a high yield strength... it just means you get a lot of elastic deformation, which isn't necessarily a bad thing.

Yep, it just means you get a lot of elastic deformation, which is a GOOD THING, especially for crank arms: they must return back to it's usual state after bending.
Look at the video when they testing the crank: it is like a spring which is good.

And you are an expert, yes ?
People are not born being so experts.

If you think I'm only on wikipedia, please don't, youre wrong.
I give it for you, the simple, one of many sources, I also gave the other links.
You could give yours. Could you ?

One more time: the spec sheets is one the first stages when you compare and choose.
And the material is a important part of the designing process: they didn't take 6061 for their cranks, they choose 7075 because it's properties give much more freedom for the further designing process. Especialy the cross sectional area, which can be made, for example, smaller comparing to 6061 or other SOFT alloy because of the 7075T6 properties. Crank can be made lighter using much burlier alloy because the density is almost the same.

The 6061T6 has only 3GPa less modulus of 69GPa
The 2014T6 has Modulus of Elasticity of 73.1 GPa
So what ?
But the hardness and UTS are differ very much and HOPE choosed 7075T6 not a 6061 or 2014.
  • + 1
 Let's stop this because we talk about the same things.
  • + 2
 My source is I do this all day every day. And by this I mean designing stuff Boeing will use to autonomously. Honestly I have to spend about 30 minutes piecing together what you say because it's hardly english. Large elastic deformation is not good. If your crank twists too much your foot will slip off the pedal and that's never fun. The point of the suspension is to absorb those forces. How a crank behaves during testing isn't always what it is desired to do. Tests like that are almost always done above the design load to prove that it will not break and that it has a certain factor of safety. There is also nothing inherently wrong with soft. One of the points for design against fatigue is design for failure. Having a part that will bend prior to failing catastrophically is desirable. 6061 gives you this, but 7075 is brittle so it will fracture right when it begins to yield pretty much. This is why you see 6061 bars in the mix. A bent bar is much better than being stabbed by a broken bar.
  • + 1
 Sorry for english, this is not my native language.
Nevertheless, many english-native people told me my english is excellent other times.

But that's not the matter.

>Large elastic deformation is not good. If your crank twists too much your foot will slip off the pedal and that's never fun.
Totally agree. But the large modulus of elasticity is very good.
You seem indeed did not understand me.
The higher number of modulus shown the more force is needed to start the elastic deformation and to make it permanent, isn't it ?
The crank should be as rigid as possible, ideally - not bending, while when the force is high enough to start the deformation the crank should return back to it's state after the force is taken off.
  • + 1
 " There is also nothing inherently wrong with soft. One of the points for design against fatigue is design for failure. Having a part that will bend prior to failing catastrophically is desirable. 6061 gives you this, but 7075 is brittle so it will fracture right when it begins to yield pretty much. This is why you see 6061 bars in the mix. A bent bar is much better than being stabbed by a broken bar."

I totally disagree with this. I heared already such opinion from some other people and that' just wrong. I have lot experience making parts of 7075T6.

- It can be made brittle by wrong heat treatment, you can make it NON-brittle by special treatment, and the optimal is T6, T654.
- Do you know about 7075O(if I'm correct on letter ) ? Anneal 7075 which is so soft, bends like ..it in any direction many times.
- You miss one thing: The 7075T6 will start to only bend when the 6061 will be already permanently deformed ot even broken.
In other words 7075T6 has huge reserve against soft 6061 or others.
Yep, in the end 7075T6 will be broken, as any, but WHEN ?
Man, it's "end" is 3 or more times far beyond the "end" of 6061.
(HOPE you understand what I mean, because I'm already tired.)
- there are the very expensive bars made of 7075T6, 2014, 7050.
- fork stanctions' kinda standart alloy now is 7050T6
- the 6061 is cheaper and softer, but the main thing - it is very well weldable( as 7005) vs 7075 which is not at all.
- also 6061 and 7005 is very well for tubing because of it's properties which you mentioned
And the bars are tubes actually so that's why non7075 used and it is enough robust for bars.
  • + 4
 I could watch these videos all day, every day. I'm greedy but I always wish these were an hour long ,they're just so compelling to watch. Credit to Steel City Media there for a sick job on the filming, the anodising/ etching sequence was awesome. The cranks emerging from the anodising bath was like something from Alien lol. Such an inspiring company, long live Hope Tech.
  • + 3
 That was an amazing video. As a mechanical/manufacturing engineer, I really enjoy seeing the entire manufacturing process under one roof. Hope is the Chris King of the UK Smile Smile . One thing that concerns me, I didn't see any of the workers wearing safety glasses. I can't walk into my company without safety shoes, glasses and ear plugs. I will be sporting a set of these cranks.
  • + 7
 The fact that they're metal, solid AND lighter than xo downhill makes them worth it I'd say
  • + 2
 More of these vids please!!!!! I loved this!!!

I don't get the pinch-bolt statement though. A weak point? I haven't used MTB cranks since ISIS Drive. I just got fed up dumping scrilla to replace shit that creaks & snaps so I started running BMX stuff & for cranks, to me pinch-bolts were the answer. A properly designed spline is necessary too of course but the triangular shaped one on those hopes doesn't look like it's up to the task, and no way to pinch it? Looks like a creaky nightmare to me. The large spindle diameter would go a long way but it doesn't look nearly as tough as a pinched cro-mo BMX tube. Id love it if I was wrong though. It looks like MTB cranks have come a long way since the bad ol' days with those fat spindles. Square splines with round roots are better than triangles though. That should be obvious.
  • + 2
 When I saw these pop-up a couple weeks ago, I was expecting to see a price tag of $600 USD minimum since it said Hope on it and was completely CNC'd. Seeing them at only $350 USD is pretty awesome.

If I'll be honest though, while I absolutely LOVE Hope products, if I buy a set of "Made in the UK" cranks...they'll be Middleburns without even hesitating.
  • + 2
 I've used my fair share of Hope kit over the last decade and a half, but isn't it a bit early to be calling these reliable?? In five years maybe, when they outlast SLX/XT/Saint cranks, but for the thick end of £300 (as per post above ^ ) I'll I'll stick with the big 'S' for now....
  • + 2
 Guillaume is, apparently, from the French quarter of Barnoldswick!
  • + 2
 i saw the cranks yesterday at the CORE bike show, they are a work of art and the axle and bolt interface are amazing. True hope quality and engineering quality. my next set of cranks will be these.. the fact that you can change the crank arms and spiders as well as fit a shorter or longer BB unit to the same arm is a sure winner. as someone said before, probably the last set you would ever need to buy, backed up with hopes awesome customer service...
  • + 6
 Amazing insight from a great company.
  • + 3
 I'm in the market for some new cranks, i was thinking carbon but these look bomb proof. Although a little pricey.
  • + 2
 If your going to spend that kinda cash, just get RF Sixc cranks. Handmade in Canada. on for 300.99 pounds at Chain reaction
  • + 2
 RF shit is sick, and my bike has as much as I can fit on it, but it's partly because I'm Canadian and live about 70km from the factory. So I get why Brits would want to use Hope. A locally built bike is pretty freaking cool, and the people putting thought into each and every piece are riding the same trails as you do every day, so they know exactly what works. Biking fukin rules.
  • + 1
 For those complaining about cost... Would you rather: A- Work at Wal-Mart and be able to afford lower cost cranks? B- Work at the Hope Tech factory and be able to afford the parts you are making? That's how it works. Think about it.
  • + 1
 Exactly the same process as Race Face. Same tomb stone CNC machine. Same mounting. Same near net forged process. Imitation is the greatest form of flattery. Ok the have an oversize axel. arm mounts a bit different, Good to have a choice. Oh by the way the 13000 rpm comment. That would depend on which cutter you are using. There is an optimum rpm for every machining process. Not just one RPM.
  • + 1
 Customer service is second to non. You will not have to buy a new set of cranks for many years of hard riding. Spare parts will be easily bought etc most importantly they look awesome!
  • + 1
 The most beautiful part of this video is the laser etching process.
Gorgeous!!!

But, i think Guillaume (design engineer) was trying so hard to make an effort to speak like a real british gentleman. (lol)
  • + 4
 That was almost emotional...
  • + 3
 f*cking space age factory, what's wrong with using a furnace and an anvil ?
  • + 3
 This kind of videos get me as excited almost as an adam brayton destroying berms one ...
  • + 2
 Congratulations to Hope for what seems to be a great product and huh Steel City Media put some fantastic movie together.
  • + 2
 wow I was not digging at all the look of this cranks but now I want em so bad
  • + 4
 CNC porn
  • + 3
 Long live high quality metal products like these. Nice one Hope.
  • + 2
 when it comes time to replace my cranks,i will definitely be considering these.
  • + 2
 To SRAM: that's how you do INFOMERCIAL not that crapp that you made about removing rear wheel.
  • + 1
 Sooo glad Hope didn't go with pinch bolts on the non drive arm, that woulda been a deal breaker. Sign me up for a setSmile
  • + 3
 Nice pre-worn design.
  • + 1
 Me thinks that Hope is a huge contributor to the good old media dept of pinky bike.
  • + 1
 This is a piece of art. Looking great i like to look into how our bike components are made!
  • + 1
 3-piece construction seems to have a 83 mm version for dh bikes. Is it true? Pleease!!!
  • + 1
 Great looking and functional cranks, would have thought would have made arms with hollow forging process though?
  • + 1
 Huge fan of the rough machining lines in the finished product. Makes me want to crank one out.
  • + 2
 If Hope is the DMM of cycling, what is Race Face in climbing?
  • + 1
 If one does not have quantifiable data that cankset A is better to crankset B, ones opinion is invalid.
  • + 1
 Anyone else spot the threaded cockring at 10.07?
  • + 1
 its fun to hear brits say aluminium
  • + 1
 microns? does it have to be that precise?
  • + 1
 I graduate this year... EMPLOY MEEEE!
  • + 1
 WOW! good job hope. i like these a lot.
  • + 1
 Hahaha, it's hilarious when he pats the crank at 0:27...
What a guy
  • + 1
 Any engineering internships?!!
  • + 2
 That's so fkin cool!
  • + 1
 anyone else watch digitalrev tv??? same music haaaa
  • + 1
 What's the name of the song at the end? can't find it.
  • + 1
 Sarah Frazier - Interlude
  • + 1
 When the cranks rose out of the anodizing tank I smiled
  • + 1
 EU goals
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