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  1. #1
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    S-Works Crankset Hirth Extension

    Like a few others out there I have an S-Works carbon crankset that won't work in our existing BB68/73 frames and looking for an extension piece. Saw a few posts including the one with proof it is possible but I had already contacted a machine shop that does Hirth work regularly to see what was possible.

    $170 for a single 20mm extension to let me use the road cranks in my BB73 frame but the price comes down to $75/each if I order 10. Told me the length can be customized for each one at no extra charge so checking to see if there was enough interest to spin up an order. Also checking with Mattias to see where he is at in the process as I don't want to take any business from him.

  2. #2
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    A 32mm extension would be nice to fit a fat bike.

  3. #3
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    I would buy one for $75.
    I hope we can get a few more people interested.

  4. #4
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    We are off to a good start, only been a day and have several nibbles... I will probably get 2 so I can use it in either a 68 or 73 mm shell with external cups so only need 7 more.

  5. #5
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    Perhaps this thread could be of help...?

    Tuning guarnitura Sworks per telao SCOTT PF29

  6. #6
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    Mattias was looking at doing these for much less than $75.00. I had emailed him requesting one, but never heard back from him - this is going back at least 1 year ago. I never found another source.

  7. #7
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    You will also need to source / manf a new bolt, the existing one is not long enough for anything more than a few mm spacer.

  8. #8
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    It is always cheaper if you can find a fellow hobbyist with the right equipment to do the task so if he is capable then I will gladly give him my money too. I have a friend with a small CNC machine I am trying to see if he can make the part but for now the real machine shop is my best source. They have to make a profit so I don't begrudge them the cost even though I am still trying to reduce the per unit price...

  9. #9
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    I'm interested in 1, or perhaps even 2. Probably just very short ones (like 3mm) to allow mtn cranks on 73mm BSA.
    This hasn't been done very often before, though I guess Lightning does it on all their mtn cranks - does anyone have any concerns that a slight inaccuracy in the machining would lead to a more sizeable misalignment of the cranks and therefore bearing drag or creaking?

  10. #10
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    Not sure how short it can be made but I will check with the machinist to see if there is a limit.

    I am sure if the machining were inaccurate it would cause a problem but the shop I am dealing with does some very high tolerance work so this is pretty easy for them.

  11. #11
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    Thanks NITF.
    BTW, can anyone confirm whether the road and mtn cranks are identical aside from the spindle length? So a road crank spaced to have the same axle length as a mtn crank (with a longer hirth extension) would have the same spider position (ie chain line) and Q-factor...?

  12. #12
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    I would buy one too

  13. #13
    L3X
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    I would buy one it this allows me to run a Specialized crank on my 68mm threaded SL3 $75 seems fair too.

  14. #14
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    That is what I want to do with mine so that is the plan. Looks like there is enough interest so I will start moving forward with the machine shop, once I get things finalized I will get confirmations and preferably deposits from those that are ordering one.

  15. #15
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    Making the bolt is not easy - I made one for a 26mm extension a few years ago. I have been waiting for Mattias to make the spacer for me ever since. It has a strange fine pitch thread and you need some way to make the allen key hole. I had to form the hexagonal hole so I could only make the screw out of aluminium - which may not hold up (needs testing). as such I think the bolt alone will cost you at least $50


    S-Works Crankset Hirth Extension-photo-16-06-2013-18-16-47.jpgS-Works Crankset Hirth Extension-photo-16-06-2013-18-19-19.jpg

  16. #16
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    I would be interested in one that would allow the MTB crank to work on a 73mm shell. I'm a bit worried about the bolt though, as mentioned.

  17. #17
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    Looking into the bolt now. It is an M12x1.0 bolt. It is not very common but still a standard thread so there might be a chance. I will check with the same machine shop and see how much it would add to make a matched set with the spacer and the bolt. Will post back as soon as I get some more information.

  18. #18
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    Hi NITF,

    I'm interested in getting one for $75.
    As for the 73mm BB shell, I thought Niner Air9 RDO frames have 73mm shells and have seen Specialized MTN cranks mounted on that frame.
    I'm interested in placing my cranks on a Scott Pro HT frame (92mm) BB.

    Dave

  19. #19
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    Quick update...

    The machine shop can make the bolt as well but have gotten busy at the end of the year so I will post more after the holidays. I was able to negotiate a lower price on the extension but by adding the bolt into the order it will probably go back to the original price of $75 including a matching extension and bolt set.

  20. #20
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    Hey NITF,

    I'm definitely in for one of them.
    Thanks for looking into it for us S-Works crank owners.

    Dave

  21. #21
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    Quote Originally Posted by NITF View Post
    Quick update...

    The machine shop can make the bolt as well but have gotten busy at the end of the year so I will post more after the holidays. I was able to negotiate a lower price on the extension but by adding the bolt into the order it will probably go back to the original price of $75 including a matching extension and bolt set.

    can you do a 5mm extension with matching bolt like on the italian weight weenies
    link above?

  22. #22
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    Would be interested in a 5.8mm extension + bolt like on the italian forum
    Frenchspeaking 29"ers community site http://VingtNeuf.org

  23. #23
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    What width space would be needed to put road cranks on a standard bb30 frame?

  24. #24
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    Precisely none

    They are BB30 spaced.

  25. #25
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    Yes, but the Q is far too narrow for an MTB. I guess you could space it to clear the stays and then add equal spacers outside the bearings.

  26. #26
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    Ahh, I was mistaken. I thought you were wanting to put them on a road frame.

  27. #27
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    anymore info on this?

  28. #28
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    I just got this reply today. I am going to send in my crank arms so they can start modeling the part.

    <<
    I am still busy but I have a new machine coming in a couple weeks that would make small work of your project. Perhaps could you draw up a sketch of what you are looking for and I can have one of my guys model it up. This way we could get some forward momentum going on it.

    Modern-Tec Manufacturing, Inc.
    Hirth Couplings | 5 Axis Impeller Machining | Medical Device
    >>

  29. #29
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    Thanks for the update.
    Looking forward to hearing more on the hirth couplings.

    Dave

  30. #30
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    Very interested.

    Here is a Spesh crank on a Crave...which has a threaded 73mm BB.


  31. #31
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    Quote Originally Posted by RS VR6 View Post
    Very interested.

    Here is a Spesh crank on a Crave...which has a threaded 73mm BB.

    What width Hirth spacer did you use? or do the 2014 MTB version have a wider spindle than previous versions?

  32. #32
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    I grabbed the pic off of Specialized's website. I have no idea what they did...but it shows that its possible to put that crank on a BSA BB.

  33. #33
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    Quote Originally Posted by RS VR6 View Post
    I grabbed the pic off of Specialized's website. I have no idea what they did...but it shows that its possible to put that crank on a BSA BB.
    Would love to know how that was done!

  34. #34
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    my guess is since that is Ned, he probably has a special frame with PF30

  35. #35
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    That is Overend. I'm pretty sure he rides a standard frame.

    Here is his Carve from 2012. Its got a standard bottom bracket. He's using a Zipp threaded bottom bracket for a Vuka crank. The BB cups have 30mm openings.

    Specialized's Upcoming Carve 29" Alloy Hardtail Will Use Post Mount Brake Tabs. Photos | Cyclingnews.com

  36. #36
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    except on this newer one there are no visable bb cups

  37. #37
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    He's riding a SS in that pic. Chances are its this that he's riding his 2013...painted in 2014 colors?



    This is the Rockhopper he rode in 2009-2010.

    Pro Bike: Ned Overend’s Specialized Rockhopper SL Singlespeed | Cyclingnews.com

  38. #38
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    it's not a ss and there are no bolts under the bb anyways

  39. #39
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    Lol...I need to look at my pics more carefully.

    Well...he did run those cranks on previous models.

  40. #40
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  41. #41
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    Heard back and the machine shop has done the CAD work and said they can do 3.5mm or more of extension and will do $55 for the spacer but they asked if I could find another source for the bolt as their lathe time is too limited and they would have to charge too much to make it worth their effort.

    I am currently checking some local machine shops to see what kind of pricing I can get on the bolt.

  42. #42
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    cool, hopefully we can get these going in the next few weeks.

  43. #43
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    Yes please. I bought a set of Road cranks. I haven't rcvd them yet. Is it plausible that my extension could need to be as much as 25mm? The seller thinks the total axle length is about 70mm (could he have meant 90mm?). I am installing it on a 73mm BSA frame with Zipp Vuma Quad cups.

  44. #44
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    Quote Originally Posted by BlownCivic View Post
    Yes please. I bought a set of Road cranks. I haven't rcvd them yet. Is it plausible that my extension could need to be as much as 25mm? The seller thinks the total axle length is about 70mm (could he have meant 90mm?). I am installing it on a 73mm BSA frame with Zipp Vuma Quad cups.
    I think the road version has a 74 mm spindle. The MTB is 90.7mm.

  45. #45
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    So I got my cranks and am ready to order a 25mm extension. So do we just call Modern-Tec and place an order? Also, any leads on a bolt yet? I'm up for Ti.

    EDIT *** I found M12 x 1.0 x 50mm socket head grade 2 (double the strength of stainless steel) titanium bolts for $11.09 each, but the supplier has a minimum order of 30 pieces. So who's up for buying a bolt for $55, and ending up with 4 spares? There's no way I'm going on the hook for the whole $335, but I'd go for $55 if anyone else is up for the same.

    They have button head and taper head grade 2 for $8.87 each. The Grade 5 Ti (6al4v) is $10.85 each.

  46. #46
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    C'mon guys! All I need is the extension and a bolt and I can install my nice new lightweight crank setup. Hurry, hurry!!!


  47. #47
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    I am looking for a local supplier with a small minimum quantity for the bolts but if anyone else comes up with a source I am fine with buying one from them.

  48. #48
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    Where do we stand on getting the extensions from Modern Tec? I would have ordered one a week ago if I could have. I have a local machinist that might be able to take a 5/8-13 2 1/2" Ti bolt and turn it into an M12x1.0 x 48mm center drilled bolt for me.

  49. #49
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    I am having no luck on a reasonable price for the bolt so far. It seems ridiculous that the bolt will be more than the extension so I am still looking. If your guy can make the bolts I will start on the extensions and we can work out the logistics of delivery offline.

  50. #50
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    I'm still interested in whatever you guys can come up with.

    Thx
    Dave

  51. #51
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    I ready to by the extension NOW! I have a bike build that I desperately want to ride, and this is the last piece I need to finish it (other than the bolt which I believe I have a local machinist that can make it for me).

    I know Mattias (Experimental Prototype) said he'd start making them April 1st (today) but I've not been able to get any news for the last week or so about whether or not he was going ahead.

    Please guys. Somebody get something rolling.

  52. #52
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    yes I want to order a 5mm now, I am told the stock bolt will work so no need for a longer 1 for me.

  53. #53
    LAN
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    I want a 5mm aswell, so I don´t need a bolt either

  54. #54
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    Well there's clearly 5 of us here that want this piece (and possibly more).

    NITF ?
    Dave Levett ?
    Peabody 5mm
    LAN 5mm
    BlownCivic 25mm

    Michael, can you get in touch with Modern Tec and ask how much these would be if we only order 5 pieces?

    Jacques

  55. #55
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    Quote Originally Posted by BlownCivic View Post
    Well there's clearly 5 of us here that want this piece (and possibly more).

    NITF ?
    Dave Levett ?
    Peabody 5mm
    LAN 5mm
    BlownCivic 25mm

    Michael, can you get in touch with Modern Tec and ask how much these would be if we only order 5 pieces?

    Jacques
    I PMed NITF for one as well. Just got my Zipp cups and I still need to measure, but likely a 4.5 mm spacer.

  56. #56
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    Quote Originally Posted by xc71 View Post
    I PMed NITF for one as well. Just got my Zipp cups and I still need to measure, but likely a 4.5 mm spacer.
    So that's 6 of us now:

    NITF ?
    Dave Levett ?
    Peabody 5mm
    LAN 5mm
    BlownCivic 25mm
    xc71 4.5mm

  57. #57
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    I am ordering a couple so we are up to 7 and on the first page we had homey2, dwaharvey, adammada33, L3X, and briscoelab show interest so i was sure we had enough to hit the 10 mark. I was just concerned about going forward if I didn't have a supplier for the bolt already lined up. If everyone else is cool with just the extension I will gladly execute on the rest of the plan.

    Anyone who is willing to go in on this please PM me and I will give you my real life details so you can contact me directly. As I will need to get the money up front I assume you will want more than an anonymous posting online...lol

    Usually for this type of situation I give my real name and my place of work email address, this way you can call the company (you can look up the number online that way you know I am not giving you a bogus switchboard) and ask for me by name which validates who I am and that there is a way to track me down.

    Once I have 8 other commits I will place the order and hopefully someone will have the bolt situation taken care of by then.

  58. #58
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    Thanks for doing this - I don't need one now.
    Last edited by adammada33; 04-11-2014 at 01:13 AM.

  59. #59
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    We are up to 7 committed orders so just 3 more to go...

  60. #60
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    what's the added cost to just do 7?

  61. #61
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    I asked the same. Either we up the cost slightly to do 7 pieces (though I suspect it'll be very very close to the same cost as 10), or we just get 10 pieces made and spread the extra cost over the 7 committed here and get little mini refunds if the extra 3 pieces get sold after the fact.

  62. #62
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    I am still waiting for some details like how long of an extension the stock bolt can support as well as the engineer is checking with some shops on a better price for the bolt. He was on vacation last week so there were no updates yet.

    Based on all the working with me he has already done without getting paid I want to stick with the original quantity of 10, so like you said we can order 3 extra of the most common size and spread the cost.

    I am pretty sure once we get the bolt issue solved we will pick up the extra 3 orders.

  63. #63
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    anything?

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    Good news, the shop doing the extension has a lathe opening up so they are able to do the bolt as well. The engineer is going to do the drawing and give me a quote later today. I had a nibble for an additional 2 extensions from someone so will let them know about the bolt solution and hope they commit.

    If we get 9 I will order an extra one in the most common length and cover the cost myself and just hold it until someone else expresses need.

  65. #65
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    If we only have 7, I'll pay the appropriate amount (another $24) to make this go forward. Are they going to quote the bolt in Ti or Stainless? I'd prefer Ti, center drilled just like the OEM bolt. And I need my bolt to be 48mm under head length with the same amount of threading as OEM Specialized.

  66. #66
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    Sorry to come in so late on this post but I am keen to get an extension to run the sworks mtb crank on my spesh Fatboy (100mm PF30 BB). have I missed the boat?

  67. #67
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    Quote Originally Posted by Jayisbikes View Post
    have I missed the boat?
    Definitely not. The project is still under development. 7 of us have paid for extensions. We're just waiting for a few more details to be ironed out. Have a read through the last couple months of this thread. All the details are there. NITF is point man.

  68. #68
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    Received some good and bad news about the bolt. Good news is that the 5mm extensions should not need a new bolt but for anyone that is looking at the 25mm version to run it with the VumaQuad type cups then a new bolt will be needed. I am going to get one that is 25mm and another that is as long as the existing bolt will support and consider facing my bottom bracket shell down to the appropriate width.

  69. #69
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    So is Modern Tec able to supply longer bolts? Did you get any pricing?

  70. #70
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    let's get this rolling, it's almost june now......was hoping to have already had it.
    can you order the extensions now and deal with the bolt seperately?

  71. #71
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    Ya! Let's get this going? I need to finish my bike.

  72. #72
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    So I have not been able to get in touch with NITF (Michael) for about a week now. Has anyone else talked to him in the last couple days? I'm losing patience.

  73. #73
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    hey nitf let me know if these are going to be ordered by next weekend, otherwise i'll probably just cancel the order.

  74. #74
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    nitf can you cancel my order and refund me

  75. #75
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    Ditto. Michael (NITF) please refund my $61 in full ($55 for the extension and $6 shipping). I have waited long enough.

    Jacques

  76. #76
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    To NITF's credit, he refunded my money within about 60 minutes of me asking for it back. No muss, no fuss.

    For anyone that still wants an extension, Mattias Hellore (Experimental Prototype) has told me that he will start production in early June.

    Jacques

  77. #77
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    Quote Originally Posted by BlownCivic View Post
    To NITF's credit, he refunded my money within about 60 minutes of me asking for it back. No muss, no fuss.

    For anyone that still wants an extension, Mattias Hellore (Experimental Prototype) has told me that he will start production in early June.

    Jacques
    i haven't seen any refund yet...how do you get ahold of mattias?

  78. #78
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    Quote Originally Posted by peabody View Post
    i haven't seen any refund yet...how do you get ahold of mattias?
    Try emailing NITF.

    Mattias has a website and a Facebook page for his company.

  79. #79
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    Not to rain on anyone's parade, but if you check out Spec's website you'll see that they've completely redesigned the new S-Works mountain cranks

    http://www.specialized.com/us/en/ftb...-arm-mtn-50397


    The new design looks exactly like the FSA SL-K carbon cranks I have on my Specialized road bike, minus the integrated spider.

  80. #80
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    Looks like Mattias will be at production soon so I am going to halt my efforts. I have refunded those that asked and will be sending the money back to everyone else today. In order to keep the costs down I have been waiting for free time on the CNC machine but they have been very busy and we haven't been able to make any progress. I will probably join the rest of you and order through Mattias. Always difficult to get small batch custom precision parts made affordably.

  81. #81
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    Quote Originally Posted by llamma View Post
    Not to rain on anyone's parade, but if you check out Spec's website you'll see that they've completely redesigned the new S-Works mountain cranks

    Specialized Bicycle Components


    The new design looks exactly like the FSA SL-K carbon cranks I have on my Specialized road bike, minus the integrated spider.
    Looks like no more 180mm, unless those are coming later.

    -D

  82. #82
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    I'm a bit late to this party, but wouldn't it be MUCH simpler to remove 2.5mm from each side of the BB bracket shell? Plus, you're removing a couple grams, not adding as with the extension....
    My bike MCA kinda climbs like a billy-goat. WOO WOO!

  83. #83
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    explain how you do this on a new carbon s works stumpy ht.....not to mention the crank arms would probably just touch the chainstays

  84. #84
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    I was thinking from my 73mm threaded bb shell. Using an e.13 adaptor BB.


    Wouldn't an S-Works Stumpy HAVE s-works cranks already??
    My bike MCA kinda climbs like a billy-goat. WOO WOO!

  85. #85
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    Quote Originally Posted by shupack View Post
    I was thinking from my 73mm threaded bb shell. Using an e.13 adaptor BB.


    Wouldn't an S-Works Stumpy HAVE s-works cranks already??
    I would have chainstay clearance issues removing 2.5mm from the BB, plus I'm not to keen on butchering a carbon Scott Spark RC frame.
    S-works Stumpy may come with XX1 cranks.

  86. #86
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    don't want 167mm Q factor....with rd crank and 5mm extender it will be 152mm and clear my chain stays by 3mm

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    Did these ever get made? And what size is needed for a 2014 fatboy? Thanks

  88. #88
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    Quote Originally Posted by turbo addict View Post
    Did these ever get made? And what size is needed for a 2014 fatboy? Thanks
    No they didn't, I believe the machine shop bailed. I'm still looking for two Hirth spacers.

  89. #89
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    I got a 25mm extension from Mattias Hellore from Experimental Prototype in Sweden. I got a local machinist to make me a longer bolt in titanium.

  90. #90
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    I would LOVE to order a 5mm hirth extension, if there is someone that would still be able to make these.

    I wish I still had access to a cnc shop, or I'd just make a bunch myself, and sell them as needed.

  91. #91
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    Quote Originally Posted by turbogrover View Post
    I would LOVE to order a 5mm hirth extension, if there is someone that would still be able to make these.

    I wish I still had access to a cnc shop, or I'd just make a bunch myself, and sell them as needed.
    I'm in for one as well.

  92. #92
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    You can buy the extension here:
    Don't forget the longer screw that you need...
    experimental

  93. #93
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    S-Works Crankset Hirth Extension

    Quote Originally Posted by larres View Post
    You can buy the extension here:
    Don't forget the longer screw that you need...
    experimental
    I thought a longer screw wasn't needed for 5mm extension? If needed, has anyone sourced one?

  94. #94
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    You can buy the longer screw there also...

  95. #95
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    Thanks! Have you tried this? Love to hear specifics. I'm thinking of using on BSA 73mm with raceface bottom bracket for 30mm spindles (used on their Next SL cranks)

  96. #96
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    No, never tried this.
    But I am thinking of doing that because I have a specialized crank here...

    The raceface bottom bracket is very good.
    I have a bracket from rotor actually on my bike and that isn't as smooth as the raceface one. Even the rotor ceramic version isn't that smooth as the raceface. But the raceface bracket is a little wider and I didn't get the rotor rex 1.1 properly mounted with the raceface one that was already installed in my bike. So I had to switch to rotor brackets... :-(
    (I know only the 30mm versions for BB89/92)

  97. #97
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    bolt cost

    went to website-- am I missing something or is he asking $45 EU for the bolt in addition to the $45 EU for the spacer?

    Also, can anyone confirm if new bolt is needed for the 5mm extension?

  98. #98
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    I am running a 25mm Experimental Prototype extension with my road Specialized cranks in the 73mm BB on my Yeti ASR5 carbon with Zipp Vuma Quad bottom bracket. My bolt was made by a local machinist from titanium, because it is 25mm longer than the std Specialized bolt. The bolt cost me $125 Canadian. It was $25 for a large Ti bolt that could be machined down to the correct dimensions (cheaper than buying Ti raw material in small quantities), and then $100 for machining.

    45 euro for the correct bolt from EP is cheap.

  99. #99
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    S-Works Crankset Hirth Extension

    I get it. Surprised but makes sense. Also since on website the pic they use for both items is the extension photo, I was also confused.

    Still wondering, is one needed for the 5mm extension?

  100. #100
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    Are you sure all you need is a 5mm extension?

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