# Ok so why aren't more people using this crank??



## vizsladog (Mar 15, 2009)

Did a search and didnt see much said about it...

Aerozine x12 sl

Q-factor is supposed to be 168.

740gr for everything including bb

and the arms are light!!









race face next carbon for comparison.


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## raceer2 (Jul 21, 2007)

flexy!


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## DeeEight (Jan 13, 2004)

If that is the Aerozine with the Al BB spindle then yes, hello Flex batman.


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## scooter916 (Jan 2, 2006)

the arms are also missing the pedal inserts, that should be worth a good 30-40g


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## crazy8 (Apr 21, 2009)

I've got experience with the Aerozine X12 made with steel and ti axles and don't notice them having flex. Do you think the Al axle would have more? Does the Al have a weight limit like the ti? Using these arms makes for a really light geared or single speed crank at a reasonable price. Pic is 175mm, ti axle, with HBC Al ring, at 494g


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## hellocook (Nov 5, 2006)

i am running them on a singlespeed for almost 2 years, no flex despite of my 200lbs. i strongly doubt the posters above have ever tried these by themselves - or they would qualify for the next biggest looser show. the complete weight with rings, bb and even the little shims is 730g.

fyi, on my geared bikes i am running xtr and can not feel any difference.

and i am pretty sure the shims are less than 10g both but don't feel like removing the pedals just to find out.

just purchased a second set for my wifes bike.


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## vizsladog (Mar 15, 2009)

thanks for the info


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## Soya (Jun 22, 2007)

I feel no flex on my aluminum axled set, I'm 190lbs and ride all mountain with them. With Mattias rings my set came to 670gr. And I still spent about $40 less than a XTR M970.


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## crank1979 (Feb 3, 2006)

I ran them a while ago on my Anthem. They flex. It was most noticeable when switching between bikes with Shimano or RF cranks.


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## DeeEight (Jan 13, 2004)

Al is about 1/3 as stiff as steel, and Ti 2/3 for equal diameter parts. Since you can't go up in BB spindle diameter without using larger bearings, the Al spindle WILL ABSOLUTELY flex more than the titanium or steel versions. To get an Al shaft as stiff as the steel one, you'd have to increase the diameter about 27%.


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## hellocook (Nov 5, 2006)

yeaah, nice math but kinda worthless.

the question is much more whether you are bringing the titanium / steel shaft cranks to the limit.

i am not even close of getting the xtr cranks to flex - and even with 27% stiffness it looks like i am still fine (and so will be 99% of all bikers).


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## aussie_yeti (Apr 27, 2004)

The aerozine cranks have more clearance to my chainstays than my X.X cranks. I can't make the X.X cranks touch the chainstays, the aerozine cranks did. I wouldn't recommend them, they were the steel spindled model.


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## Broccoli (Jun 11, 2008)

DeeEight said:


> Al is about 1/3 as stiff as steel, and Ti 2/3 for equal diameter parts. Since you can't go up in BB spindle diameter without using larger bearings, the Al spindle WILL ABSOLUTELY flex more than the titanium or steel versions. To get an Al shaft as stiff as the steel one, you'd have to increase the diameter about 27%.


That would be somewhat relevant if a) the spindle was supported in the middle. b) all material had the same wall thickness.


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## checky (Jan 13, 2006)

I had three sets of this cranks (cause first impression was good).
First with Ti axle. Flex was only noticable when pushing the crank arm by hand to the chain stay. During riding no flex noticable.
My other two sets had alu axles and these where very flexy. Next was the pedal inserts: they make creaking noises, also with copper paste, or Loctite. Found no solution.
At one crank the alu crank arm bolt seizure. Had to destroy it to get it out. At all three cranks the BB was crap. Had to exchange it to Shimano. At one crank the 22 ring breakaway, dont knoiw the reason. After this happend the 22 ring was buckled. Cannot mount it ones more, it looks like an egg.
In summ I cannot recommend these cranks.


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## eliflap (Dec 13, 2007)

vizsladog said:


> Ok so why aren't more people using this crank??


maybe for the stupid BDC ...94mm 4 arms ........ :nono: :nono: who sells chainrings for spare in that BCD ?

another BCD ... but Aerozine is not big as Sram ( with its 120-80mm BCD :madmax: ...but they can do all they want ... )


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## Jake Pay (Dec 27, 2006)

eliflap said:


> maybe for the stupid BDC ...94mm 4 arms ........ :


Nough said :madman:​


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## DeeEight (Jan 13, 2004)

Yes a proprietary bolt pattern would cut into sales as well. Plus they're damned expensive for something that creaks more, flexes more, and are less durable. But hey they have fancy annodized colours and they're light which is good for weenies who never really ride.


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## xcatax (Mar 26, 2009)

vizsladog said:


> Did a search and didnt see much said about it...
> 
> Aerozine x12 sl
> 
> ...


You are not good enough
try searching Google "aerozine mtbr" 238 results
and btw Aerozine cranks :thumbsup:


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## crazy8 (Apr 21, 2009)

*Aerozine X12 bcd*

All the Aerozine cranks I've had were 104/64bcd. Has it been changed??


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## MessagefromTate (Jul 12, 2007)

hellocook said:


> yeaah, nice math but kinda worthless.
> 
> the question is much more whether you are bringing the titanium / steel shaft cranks to the limit.
> 
> i am not even close of getting the xtr cranks to flex - and even with 27% stiffness it looks like i am still fine (and so will be 99% of all bikers).


except that aluminum will fatigue quicker through repeated exposure close to the yield figures cited but of course the opinions of a guy that uses his road bike to downhill doesn't apply to the skillz the rest of us display. You must be the smoothest rider on the planet...


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## rockyuphill (Nov 28, 2004)

It appears that only the X12-SL-A2D dual ring cranks are 94/64, all the triples are 104/64


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## Mattias_Hellöre (Oct 2, 2005)

I would recommend against 94mm FSA 4 bolt circle as it requires STIFF chainrings to shift properly and not fold under power.

I recommend 5 bolt cranksets at least 110mm BCD for serious riding.

In a ideal world it should be a 130mm BCD for bigring, then 74mm BCD for granny, of course we are talking about 5 bolt spiders here.


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## bad mechanic (Jun 21, 2006)

DeeEight said:


> To get an Al shaft as stiff as the steel one, you'd have to increase the diameter about 27%.


...or increase the wall thickness.


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## DeeEight (Jan 13, 2004)

You'd have to significantly increase the wall thickness... and if you look at the Aerozine crank end on the driveside, its pretty clear that the shaft isn't any thicker. You'd basically be needing to triple the wall thickness compared to the steel one. This is why with bicycle frames, not only do aluminium tube walls grow in diameter compared to steel tubes, but they often also increase in wall thickness because there is a limit on the available diameter of tubing they can use. The actual increase in thickness needed to equal steel using aluminium tubing of the same O.D. would be about 2 1/2 times. So if the steel piece has a thickness of 1.2mm the Al one would need to be at least 3.5mm thick. Anyone have a set of calipers handy with some Aerozine Al shaft cranks and say some Raceface Deus cranks (which are a good benchmark for stiffness among XC cranks with steel shafts) ?


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## bad mechanic (Jun 21, 2006)

You're right, they don't appear to be thicker, but it's a little hard to see in the picture. I'm just thinking of the Shimano Hone/LX crankset which used aluminum with a thicker wall, and those seemed to work quite well.


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## DeeEight (Jan 13, 2004)

Its too bad all the Pink ones on ebay lately seem to be the Al shaft ones as the colour would match up well for a project I'm gathering bits for but since its into the All-Mountain/Trail bike category of builds, I'd rather not use a crank whose BB shaft is going to *A* flex more and *B* likely result in a fatigue failure at an unpredictable time just to save a few grams and get a nice shade of pink. Plus the damn things are still quite expensive. I can get a brand Raceface Deus crankset for a third less and with far superior construction and especially chainring quality. Hmmm wonder if I can find a white set of Deus cranks and run a Pink annodized bashguard.


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## Jake Pay (Dec 27, 2006)

*vip15 (coupon 15% off)*

https://www.universalcycles.com/shopping/product_details.php?id=31591​


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## rockyuphill (Nov 28, 2004)

Or the pink Noir 3.3

http://www.universalcycles.com/shopping/product_details.php?id=31722&category=381


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## bad mechanic (Jun 21, 2006)

Or get your crank of choice ceramic coated by crazy8.


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## DeeEight (Jan 13, 2004)

rockyuphill said:


> Or the pink Noir 3.3
> 
> http://www.universalcycles.com/shopping/product_details.php?id=31722&category=381


don't you know about bicyclette de hull yet?

http://cgi.ebay.ca/Truvativ-Noir-Pi...Cycling_Parts_Accessories&hash=item5193e6fa94


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## Nozes (Feb 18, 2008)

Race Face Deus= 840 grams
Truvativ Noir= 820 grams

And I thought this was the WW forum...Aerozine cranksets may be flexy (I will see about that,but beeing a light spinner,I'm not that worried),but they are LIGHT for the money,I bought the X12SL aluminum axle version on a flash promotion in a big european online store for 129€ (!).
Weight with photos due by friday,stay tuned


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## Axis II (May 10, 2004)

Nozes said:


> Race Face Deus= 840 grams
> Truvativ Noir= 820 grams
> 
> And I thought this was the WW forum...Aerozine cranksets may be flexy (I will see about that,but beeing a light spinner,I'm not that worried),but they are LIGHT for the money,I bought the X12SL aluminum axle version on a flash promotion in a big european online store for 129€ (!).
> Weight with photos due by friday,stay tuned


Many people complained about flex with these cranks years ago. The verdict has been in for a while. Lets move on


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## DeeEight (Jan 13, 2004)

I also don't buy the "I can push them with my hands but don't feel it with my feet" analogy. I could push old Deore DX cranks inwards by hand and when I actually looked down while riding sure enough I saw the things flexing. I couldn't feel it in either my feet or knees which were doing their own monkey motions but damned if it wasn't clearly visible.

I'm sure the flex isn't any more than you'd get with a square-taper Ti BB setup and an older set of cranks like Raceface Next LPs or something similar... but then if you're willing to accept that sort of motion, the square taper setup will be lighter, cheaper and the bearings will last YEARS. 

Again... is there any mystery why more of us are not using these aerozine cranks?

Now if you'll excuse me, I think i just passed a kidney stone and I plan to drink a couple liters of water to verify that theory.


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## xcatax (Mar 26, 2009)

We are using these cranks check for post in WW forums , theres alot people talking about same bs ofc same people posting same pics same crap .
I have got middleburn rs8 with ti square taper bb 107mm and i know this flex uphill , areozine cranks seems enought stiff that i didnt notice .
The bad we users all know is .......... paint , bb ..... bb is replaced one time in 1 year and my brother pass on paint










+1year and still working fine in mikes bike 8,32kg
Salu2
Juan


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## morrisgarages (Jan 25, 2009)

xcatax, where'd you get your chainguide? What's the weight?


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## xcatax (Mar 26, 2009)

morrisgarages said:


> xcatax, where'd you get your chainguide? What's the weight?


 I bought this 25e 400x200x2,5mm










...........and made a copy of mrp but lightweight .































Salu2
Juan


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## fastback67 (Apr 6, 2010)

DeeEight said:


> I also don't buy the "I can push them with my hands but don't feel it with my feet" analogy. I could push old Deore DX cranks inwards by hand and when I actually looked down while riding sure enough I saw the things flexing. I couldn't feel it in either my feet or knees which were doing their own monkey motions but damned if it wasn't clearly visible..


thats could be simple: dx were square taper and the flex is in the small bb axle.
at the earozine the flex beginns behind the spider. only the arm flexes and therefore you see no flex at the rings cause they are nearly one part with the stiff 24mm axle.
perhaps.


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## DeeEight (Jan 13, 2004)

Actually no, in DX cranks the spindle didn't flex (really a 17mm CrMo spindle takes a LOT of force to actually get to bend) it was all in the arms, and I was watching the end of those arms move inwards towards my chainstays. The rings weren't shifting out of position at all.


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## Jake Pay (Dec 27, 2006)

What's the consensus on the Aerozine BBs..(claimed 94g)?

Durability?

Cost?

I'm using M960 and M970 on my RF NEXT cranks and I'm wondering if the Aerozine offers 
a BB cheap enough to use as a throw away for those super muddy seasons.









TIA























*Total: 624g,*​


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## xcatax (Mar 26, 2009)

Jake , the shimano deore bb cost is 12e ( 98g) here Ciclos Albacar Zaragoza (spain) .
Pic SLX thats same as deore










Aerozine cranks is another product like Hygia usagi brakes , theres no others can beat their prices . We users can have good stuff for low prices but there are people still blind with words like .......... got it?

Im happy with my low-cost bikes 8,32kg & 7,33kg
Salu2
Juan


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## Soya (Jun 22, 2007)

My Aerozine bb has been working fine on my XC Trek, no noticeable difference from a shimano bb.


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## G (Feb 22, 2010)

Is 716 grams pretty good for a double chainring crank?

http://cgi.ebay.com/NEW-AEROZINE-X-...7247QQcategoryZ56193QQcmdZViewItem#vi-content

Considering this for my Sette Razzo frame...


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## crazy8 (Apr 21, 2009)

Token BB and Aerozine were the same mfg and probably still are. They both use the same bearings SKF CrMo and Tiramic ceramic. Aerozine does have a unit with ti cups though I wouldn't think it necessary. It's been my experience that both are good quality and reasonably priced.


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## xcatax (Mar 26, 2009)

I try to say that Aerozine bb is not the reason for its cheap price coz you can have a good bb for 12e also lightweight .


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## Nozes (Feb 18, 2008)

As promised,here are the real weights for the Aerozine X12-SL crankset.
Total weight includes all 3 spacers for the BB (9gr).










That's 2.4% off the claimed 730gr,as I expected.










This is clearly heavy,and will be changed for a 42t MSC chainring (60gr).










My frame has a 73mm wide BB,so just one of the spacers will be used,taking the weight down to 89gr.The plastic protection weights 7gr.Ceramic bearings.

All this for 129€!


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## checky (Jan 13, 2006)




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## Nozes (Feb 18, 2008)

Better not sell my Stylo OCT then!


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## xcatax (Mar 26, 2009)

Thats the painting , mines looks worst lol but still working as intended or better 1x9


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## crazy8 (Apr 21, 2009)

I had this happen with a new AZ with the ti axle a couple yrs ago. They said it was only a issue with the ti axle and hadn't had a problem with any of the CrMo sets. What axle does this one have?


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## loggerhead (Mar 8, 2009)

hellocook said:


> i am running them on a singlespeed for almost 2 years, no flex despite of my 200lbs. i strongly doubt the posters above have ever tried these by themselves - or they would qualify for the next biggest looser show. the complete weight with rings, bb and even the little shims is 730g.
> 
> fyi, on my geared bikes i am running xtr and can not feel any difference.
> 
> ...


i dont get how the set pictured with the orange ring is under 500 grams when a 'completed set' (i guess 3 rings and a few alu. bolts) brings the weight up to 730? is that accurate?


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## nino (Jan 13, 2004)

loggerhead said:


> i dont get how the set pictured with the orange ring is under 500 grams when a 'completed set' (i guess 3 rings and a few alu. bolts) brings the weight up to 730? is that accurate?


Easy to explain - there is no BB...that weighs around 100g


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## loggerhead (Mar 8, 2009)

i see. forgot about the cups.


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## Veda (Dec 17, 2009)

The X12-SL doesn't flex assuming you have them installed right which can be downright almost impossible unless you find a really experienced mechanic. Take it from someone who uses this exact crank on all his bikes, me. Yes it's a hassle but once you got them set up right they're quite durable for XC racing purposes. All in all, a nice lighter alternative to the XTR. I'm gonna get the Aerozine X12-SL-A2D 42x29 (716gr) that should be a nicer alternative to the X-0 crank.


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## Gezzza (Jun 13, 2006)

Veda said:


> The X12-SL doesn't flex assuming you have them installed right which can be downright almost impossible unless you find a really experienced mechanic. Take it from someone who uses this exact crank on all his bikes, me. Yes it's a hassle but once you got them set up right they're quite durable for XC racing purposes. All in all, a nice lighter alternative to the XTR. I'm gonna get the Aerozine X12-SL-A2D 42x29 (716gr) that should be a nicer alternative to the X-0 crank.


installed right by a really experienced mechanic this isnt a lunar spaceship its a outboard bearing crank there not a lot to it just a couple of bolts, its not even up there with really hard jobs that you need a really really experienced mechanic for like bleeding a disk brake.


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## eddy02 (Sep 5, 2010)

hellocook said:


> yeaah, nice math but kinda worthless.
> 
> the question is much more whether you are bringing the titanium / steel shaft cranks to the limit.
> 
> i am not even close of getting the xtr cranks to flex - and even with 27% stiffness it looks like i am still fine (and so will be 99% of all bikers).


A reasonable wall thickness will have 3x the flex and half the strength of steel (hence the 85kg rider weight limit). A solid bar of 7000 series Al will have 2.8x more flex. Aluminum is flexy and IMHO not strong enough in a 24mm spindle application.

sorry weight limit was assuming it was the same crank as this: 
http://www.actionsports.de/gb/Compo...nclCeramic-Innenlager-40-27T-710g::29299.html
it may be different.


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## Broccoli (Jun 11, 2008)

Veda said:


> which can be downright almost impossible unless you find a really experienced mechanic.


Nonsense.



Gezzza said:


> its not even up there with really hard jobs that you need a really really experienced mechanic for like bleeding a disk brake.


What is so hard about bleeding brakes?



eddy02 said:


> A reasonable wall thickness will have 3x the flex and half the strength of steel (hence the 85kg rider weight limit). A solid bar of 7000 series Al will have 2.8x more flex. Aluminum is flexy and IMHO not strong enough in a 24mm spindle application.


This is just a random collection of numbers.


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## Gezzza (Jun 13, 2006)

Curmy said:


> Nonsense.
> 
> What is so hard about bleeding brakes?


Nothing :thumbsup:

My sarcasm obviously got lost


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## Broccoli (Jun 11, 2008)

Gezzza said:


> Nothing :thumbsup:
> 
> My sarcasm obviously got lost


Sarcasm does not transmit across teh interwebz.


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## eddy02 (Sep 5, 2010)

Curmy said:


> This is just a random collection of numbers.


Your quarrel is not with me sir, it's with science.


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## biketuna (Mar 28, 2008)

I use them with my 1x9 setup with a 36t ring and don't feel any flex.


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## turbogrover (Dec 4, 2005)

where can I purchase these cranks in the US? I see the triple cranks for sale on Ebay, but I didnt even know the double crankset existed.


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## biketuna (Mar 28, 2008)

I bought my triple (removed small and large ring) on EBAY


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## Broccoli (Jun 11, 2008)

eddy02 said:


> Your quarrel is not with me sir, it's with science.


Random collection of numbers does not a science make.


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## Ausable (Jan 7, 2006)

rockyuphill said:


> It appears that only the X12-SL-A2D dual ring cranks are 94/64, all the triples are 104/64


Ok so I can get a 27/40 Aerozine Doube for a good price; I have tested the triple for one year and have no complaints. It may be flexy but I don't notice it while I'm riding: maybe because I am relatively lightweight.
And I think that a 700g crank for just over 170€ is a good deal.

The only thing holding me from ordering is this stupid BCD for the bigger chainring - but *does any other company manufacure 94mm 4-arms chairnings, or is this BCD exclusive to Aerozine?* I tried looking at the Specialites TA and Stronglight catalogs and found nothing!:skep:

The other alternative will be buying another triple and spend another 65-80€ for some aftermarket rings :madmax:

Thanks for any suggestions!


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## Ausable (Jan 7, 2006)

rockyuphill said:


> It appears that only the X12-SL-A2D dual ring cranks are 94/64, all the triples are 104/64


Ok so I can get a 27/40 Aerozine Doube for a good price; I have tested the triple for one year and have no complaints. It may be flexy but I don't notice it while I'm riding: maybe because I am relatively lightweight.
And I think that a 700g crank for just over 170€ is a good deal.

The only thing holding me from ordering is this stupid BCD for the bigger chainring - but *does any other company manufacure 94mm 4-arms chairnings, or is this BCD exclusive to Aerozine?* I tried looking at the Specialites TA and Stronglight catalogs and found nothing!:skep: 
The other alternative will be buying another triple and spend another 65-80€ for some aftermarket rings :madmax: 
Thanks for any suggestions!


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## BlownCivic (Sep 12, 2006)

I'm pretty sure FSA ran that BCD for their carbon 2x9 cranks for a couple years, and Mattias can make you pretty much anything you want for a very reasonable price.


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## DeeEight (Jan 13, 2004)

That's all fine and good for people on here with access to mattias, but to the wider public its a stupid idea to use a proprietary ring size on a crankset only sold on ebay. I checked FSA's chainring offerings and the only 94-4bolt size is 44T. So, you're up shite creek trying to source a replacement 40T ring anyplace other than ebay.


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## crazy8 (Apr 21, 2009)

*Aerozine Cranks*

I've got Aerozine arms with 104/64 bcd ring interface. The set Mattias has pictured has a ti axle with a Token Tiramic BB at 87g. That's why it's under 600g for the complete set up. If I remember right the arms alone weighed just under 470g. I'll get some pics to show later.


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## tehan (Jan 22, 2007)

http://www.chainreactioncycles.com/Models.aspx?ModelID=35780

there is 42 and 44. And i am making 33T for 4bolt 94mm for my singlespeed


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## BlownCivic (Sep 12, 2006)

DeeEight said:


> That's all fine and good for people on here with access to mattias,


Why would anyone here NOT have access to Mattias? They may choose to not have access, but everyone that has a mailbox and has ever done any form of mail order has the choice of dealing with Mattias.


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## Mattias_Hellöre (Oct 2, 2005)

Aerozine and FSA does have a odd BCD at 94mm 4 bolt, why they choose this bolt circle is questionable but anyway, I do make these BCD fairly often now when people has worn through their bigring and looking for very limited choice of options.
REAL and Control Tech does sell them too I see.


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## DeeEight (Jan 13, 2004)

BlownCivic said:


> Why would anyone here NOT have access to Mattias? They may choose to not have access, but everyone that has a mailbox and has ever done any form of mail order has the choice of dealing with Mattias.


Turn your brain on before posting next time...

People who buy bike parts on ebay are NOT exclusively mtbr members, even the ones who buy lightweight parts like these cranks. There is a much larger world of cyclists out there than just the ones who troll this site and in particular this forum, and thus are unlikely to even know of mattias's existence let alone that he makes custom chainrings.


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## Ausable (Jan 7, 2006)

*Aerozine Double Big Ring spares*

Thanks, I've checked the CRC website and indeed FSA indeed makes some (ugly and hefty) 94mm rings, but 42 and 44 only.

MAttias, before placing the order I will PM you for price and availability of 94mm rings in 40 & 41T.

Why did Aerozine choose this stupid BCD, instead of the world standard 104mm, remains a mistery to me??


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## tehan (Jan 22, 2007)

Ausable said:


> Thanks, I've checked the CRC website and indeed FSA indeed makes some (ugly and hefty) 94mm rings, but 42 and 44 only.
> 
> MAttias, before placing the order I will PM you for price and availability of 94mm rings in 40 & 41T.
> 
> Why did Aerozine choose this stupid BCD, instead of the world standard 104mm, remains a mistery to me??


answer why is very simple - you can't make 29T on 104 BCD but on 94mm you can do it easily. And this is main reason why. They also didn't do 104/64 because this require wider BB (and Q factor) and 2x more bolts for chainrings. Mathematics is obvious
That is why FSA K-force double has so narrow Q factor (147mm, and XTR M985 is i think 165mm)

btw - this will be my new 33T for 94mm/ 4 bolts. self made - 36g . pictures are from solidworks at this moment.


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## BlownCivic (Sep 12, 2006)

DeeEight said:


> Turn your brain on before posting next time...


Oh boy! Someone overdosed on their obnoxious pills again! :nono:


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## Broccoli (Jun 11, 2008)

tehan said:


> answer why is very simple - you can't make 29T on 104 BCD but on 94mm you can do it easily.


Yep, and a year later they have switched to a three bolt setup so that they can go down to 26t.


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## Ausable (Jan 7, 2006)

tehan said:


> answer why is very simple - you can't make 29T on 104 BCD but on 94mm you can do it easily. And this is main reason why. They also didn't do 104/64 because this require wider BB (and Q factor) and 2x more bolts for chainrings. Mathematics is obvious
> That is why FSA K-force double has so narrow Q factor (147mm, and XTR M985 is i think 165mm)


Alright, now it's clear! 
I was thinking that the Aerozine double used the same system of a converted triple i.e. the 27T ring bolted to the 64mm bolts and the 40T bolted to the 94 BCD.
Now I see that both 27 and 40T rings are fitted on the 94BCD. that will also benefit chainline - which is a litte bit too narrow in converted triples vs native 2x9

Thanks for the explaination. 
fab


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## Veda (Dec 17, 2009)

Gezzza said:


> installed right by a really experienced mechanic this isnt a lunar spaceship its a outboard bearing crank there not a lot to it just a couple of bolts, its not even up there with really hard jobs that you need a really really experienced mechanic for like bleeding a disk brake.


Ever tried removing this crank's bb from a Spark 30 frame?

Btw, weighted my X12-SL-A2D 42x29 and came out to be 749gr bottom bracket included. Makes a nice cheaper alternative of the XX crank...


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## Mattias_Hellöre (Oct 2, 2005)

My main concern on changing boltcircles is two reasons.

1. Swapping to a common bolt circle is OK as long you follow it up with the number of bolts.
I.e 94mm BCD is common with FIVE bolts not four.

2. The distance between bolt hole and chainring teeths divided with numbers of bolts.

Example:
FSA 386 is meaning three bolts paired with 86mm BCD, that´s a dumb way to do that as the distance between bolthole to next bolt hole is greater PLUS bolthole to chainring teeth.

You have to make a VERY stiff chainring to resist folding or ripping away the crank tabs, = HEAVY.

My solution is to stick with 5 bolt 94mm as it´s very common and can be built with very light rings and long durability.

The track record says so.

The best would be a bolthole very near the chainring teeth paired with 6 bolts and two different bolt circles for big and granny gears.


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## Veda (Dec 17, 2009)

Mattias, any comment on Rotor's oval chainrings? Are they gimmicks or have actual benefits?


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## DeeEight (Jan 13, 2004)

Mattias... T.A. Specialities 6-bolt pattern allowed rings down to a 17T size as memory serves.


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## Mattias_Hellöre (Oct 2, 2005)

Veda said:


> Mattias, any comment on Rotor's oval chainrings? Are they gimmicks or have actual benefits?


I´m not qualified enough to say the rotors are hit or miss.

But I´ve read some biomechanical documents, the real benefits lies in a much more ovalised chainrings than osymetric and rotors.


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## Broccoli (Jun 11, 2008)

Mattias_HellÃ¶re said:


> I´m not qualified enough to say the rotors are hit or miss.
> 
> But I´ve read some biomechanical documents, the real benefits lies in a much more ovalised chainrings than osymetric and rotors.


Not sure about scientific biomechanical benefits, but I do notice that it is easier to do slow, steep technical climbing with a Rotor Q-ring 23t granny ring. It just a little taller gear at just the right moments, and pedals do hang up noticeably less on rocks - I guess it clears the dead spot faster. I wish they made a 25t granny, would be even more usable.

I did not feel like replacing my middle rings with Rotor though.


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## Mattias_Hellöre (Oct 2, 2005)

DeeEight said:


> Mattias... T.A. Specialities 6-bolt pattern allowed rings down to a 17T size as memory serves.


What kind of boltcircle is it?
A double or triple one?


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## Mattias_Hellöre (Oct 2, 2005)

Curmy said:


> Not sure about scientific biomechanical benefits, but I do notice that it is easier to do slow, steep technical climbing with a Rotor Q-ring 23t granny ring. It just a little taller gear at just the right moments, and pedals do hang up noticeably less on rocks - I guess it clears the dead spot faster. I wish they made a 25t granny, would be even more usable.
> 
> I did not feel like replacing my middle rings with Rotor though.


I´ve done oval chainrings in some odd toothcounts that rotor didn´t offer, I haven´t heard any complaints yet.


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## DeeEight (Jan 13, 2004)

Its an "any" number of chainrings one. TA's six-bolt pattern was especially popular with high end touring bike users/builders because of the wide range of ring sizes they offered and their own cranks they made. Bullseye was one of the few aftermarker component makers to adopt the TA pattern for their own cranks. For a time in the late 80s/early 90s before Suntour debuted MicroDrive gearing (and shimano copied it as compact drive), to get really low gearing on mountain bikes, these cranksets were the best way to do it.

http://www.bikepro.com/products/cranks/bullseye.shtml


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