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Thread: XT hubs?

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    XT hubs?

    hi,

    i have seen a fair bit of chat about the newer alloy axel XT hubs not being as good as the older ones and the thin steel free hub body breaking up (i have seen a photo of this some where on the net). can we put this one to bed and get the real low on the M770 hub VS the older near impossible to find hub?

    oh, i;m planning to have a set build up for a long tour and would like to get some closure on the issue assuming this rid one?

    also i'm not too keen on the lower speck hubs as i think they don;t have the coated ball races and also don;t have the same level of sealing against the elements.

    thanks d :-)

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    Senior Member pasopia's Avatar
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    I can't comment on the old ones, but I had good luck with the XT M770 hubs. My current rear hub has about 10,000 miles on it, 8,000 of which were fully loaded touring through South America. I haven't done touched the hubs and they are still running smooth. No problems at all.
    My 2010-2011 tour from Argentina to Ecuador:
    http://awesomebiketour.tumblr.com/

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    Senior Member Doug64's Avatar
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    We just got back from a 2900 mile fully loaded trip which included over 400 miles of unpaved roads and trails, and over 500 miles of cobblestone and paver block roads. The XT hubs were trouble free. I also put on about 1000 trouble free miles of loaded touring on those hubs prior to the most recent trip. The only thing I don't like about the XT hubs is the inability to preload the hubs using the quick release skewer when adjusting the bearings. This is due to the need to use a hex wrench in the the skewer opening to set the cones. It just takes a little longer to adjust them correctly. I was a little apprehensive about a touring on XTs when I first realized the axels were aluminum, but after using them and servicing them a couple of times I don't anticipate any problems. I ran into the same situation where the LX hubs were not available, and I did not realize the XT had the aluminum axels. I would have been happy with the LX hubs if I could have found some. The bike my wife used to ride (fully loaded) across the U.S. a few years ago has LX hubs, and they were also trouble free. She has used the same bike to commute with in all kinds of weather and the hubs are still in great condition. If you can finds the LX hubs and want a solid axel they are a good alternative.

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    coprolite fietsbob's Avatar
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    Bene Sugg: drop down a notch they are targeting the XC MTB , and shaving grams.
    steel axles ..

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    Shimano replaced the 10x1 threaded steel axle they've used for >20 years with a larger diameter, stiffer Al axle and end caps. This was done to appeal to MTBers who tend to jump off things and bend axles. It's basically a marketing appeal move, since it offers no real benefit to the majority of users.

    When they made the axle diameter larger, using the same hub shell dimension, it left less room for the bearing assembly. Shimano changed the 1/4" balls to 3/16" balls as a result of this "makeover". Small balls have a lower load limit and roll with more friction. I've read 2 separate reports of bearing-related 770 hub failures. Anecdotal only, but it is consistent with the design change. Shimano should have taken this opportunity to eliminate cup-and-cone ball bearings and replaced them with beefy cartridge bearings. But then their hubs would be completely serviceable with an unlimited life. As they are now, the pressed-in cup eventually gets a track eroded into it from the balls - then you have to buy a new hub and build a new wheel. A cartridge bearing upgrade would cut into lots of profit in selling replacement wheelsets.

    As fietsbob suggested, choose Deore or LX (european availablity only) hubs if you want them to still roll as reliably as Shimano MTB hubs of the past 20+ years. Better yet, spend more on some Hope, DT or similar hubs with good replaceable cartridge bearings. Also, note the service procedure for changing bearings before purchase - many require special tools and expensive, odd-sized bearings that make the cost of long-term ownership of those hubs much higher. Hope hubs are disassembled with common tools and bearings are an inexpensive size. Phil Wood is the same in this regard.
    Last edited by seeker333; 10-19-11 at 05:33 PM.

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    we be rollin' hybridbkrdr's Avatar
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    OK, if seeker333 is correct that larger bearings are more ideal for loaded touring, then the technical documents by Shimano show the LX 660 rear hub had 9 bearings and the XT770 has 13 bearings.

    If this is really true then I guess it's case closed. That's nice to know for me since I'm the one usually asking myself a billion "useless" questions. But, I saved some parts for a future project and don't have a frame or the wheels for that project yet so... hehehe

    http://techdocs.shimano.com/techdocs/index.jsp

    http://techdocs.shimano.com/techdocs...&bmUID=jbYndE6

    I believe this does make sense though because LX is now intended for trekking. But, I do believe Niagaracycle sells the 660 LX. I also know bikexperts in germany sells even the dynamo hub in LX.

    wow, that's strange, I couldn't find the 36 hole...
    http://www.niagaracycle.com/product_...ucts_id=434837

    http://www.bike-x-perts.com/en/produ...ucts_id/139874
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    Senior Member Doug64's Avatar
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    Originally posted by hybridbkrdr
    OK, if seeker333 is correct that larger bearings are more ideal for loaded touring, then the technical documents by Shimano show the LX 660 rear hub had 9 bearings and the XT770 has 13 bearings
    I did the same thing after thinking about it on my ride today (along with fixing a flat tire). I looked at Shimano's Tech pubs when I returned home and was wondering:

    If a hub has more small bearings vs. fewer larger bearings, which combination results in the most load bearing contact with the hub's race at any given time? Or does it even matter? I don't have a clue.

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    I have also been flip-flopping on which hub to use. I had decided on the LX because of a few reported problems with the XT. But then I compared the seals.

    The seals on the LX T660
    http://techdocs.shimano.com/media/te...9830648102.pdf
    do not look to be nearly as complex as the seals on the XT
    http://techdocs.shimano.com/media/te...9830621050.pdf

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    Both the LX and XT simply have one seal ring on each side according to those techdocs, Rzldzl.

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    Quote Originally Posted by Doug64 View Post
    I did the same thing after thinking about it on my ride today (along with fixing a flat tire). I looked at Shimano's Tech pubs when I returned home and was wondering:

    If a hub has more small bearings vs. fewer larger bearings, which combination results in the most load bearing contact with the hub's race at any given time? Or does it even matter? I don't have a clue.
    For decades most hub manufacturers that used cup and cone bearings have used smaller diameter ball bearings in front hubs than rear, I assume that they knew something about which bearings to use for various loads.

    I have also seen comments on the internet that the freehub is thinner on the newer hubs to make more room for the larger diameter aluminum axle. I don't save links of items I read on the internet, so to respond here I did a google search and came up with this example:
    http://pardo.net/bike/pic/fail-001/FAIL-082.html
    I assume this is a design problem.

    And, I have seen comments about the freehub not being assembled property to the shell, another google search found this:
    http://yacf.co.uk/forum/index.php?topic=20893.15
    The freehub to shell attachment failure might be a one-off assembly problem, from the internet post it is impossible to determine if it is a design problem or not.

    I have not personally had failures as described, I only cite what I have seen on the internet.

    But, when I built up another tourer two years ago I decided to use the older M760 hubs which did not have the reported failures that the newer ones had. I found it interesting that at that time Surly used the M756 hub on their cargo bike (the Big Dummy) and the M770 on the LHT touring bike (source: 2010 catalog). I assumed that the cargo bike would need the heavier duty hubs, thus I concluded that I should stick with the older design.

    But for my foldup bike I used the M770 for the front hub. I got a good price on the M770, that was part of the decision. I have not seen any negative comments on the newer XT front hubs and the folding bike front hub does not take heavy loads. (The rear hub on my foldup bike is not a Shimano hub.)

    Surly 2011 catalog lists the Big Dummy hubs as Deore whereas the LHT is still on M770 XT hubs. Thus, if I was building up a touring bike wheel today, I would consider the Deore hub as a viable option too. I do not have any personal experience with LX.

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    I challenged a poster on another thread who regularly disparages XT M770 hubs at their mere mention (8 times and counting) to provide some evidence of the "XT problem". I'm still waiting. To my knowledge, this poster as well as most of the respondents on this thread has never, ya know, actually used M770 hubs.

    Where's the problem? Shouldn't we expect to see more than "2 separate reports" of hub failures if there's an epidemic out there, especially since Shimano has sold boatloads of these hubs over the last five years? Why aren't Surly owners up in arms? The LHT "complete", one of the most popular touring bikes of recent years, has been equipped with M770 hubs for four model years (2008-2011). Why aren't the trekking (aka touring) bike owners in Europe with these hubs complaining? They're not and the M770 hub remains part of Shimano's premier trekking group sold there (no, it's not just an mtb hub).

    Second, if an M770 hub fails, why is it automatically assumed that the cause was its aluminum axle and smaller bearings? Correlation does not imply causation. Since when did aluminum become a no-no material for a bike part? Have you taken a look at your bike lately and counted how many load-bearing components are made of aluminum? And it's not like aluminum-axled XT hubs are anything new. I have a 15 year old HB-M738 hub with (gasp!) an aluminum axle that still rolls as nicely as the day it left the factory.

    It is far more likely that if an XT hub breaks it is for the same reason that all cup-and-cone hubs fail: improper maintenance. Cup-and-cone hubs need periodic cleaning and re-greasing and their bearings need to be properly adjusted or they will fail. If the owner accepts this maintenance obligation, he will be rewarded with virtually drag-less performance and easy field serviceability out in the Middle of Nowhere™.

    I'd like to see some real data points regarding this alleged "XT problem" and not the "concern"-mongering, "Some say.."-ing, and internet folklore regurgitating that seems to accompany this topic whenever it's raised.

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    we be rollin' hybridbkrdr's Avatar
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    I noticed when looking at the technical documents that the XT hubs have way more parts to the sides of the bearings. Does this mean the XT hubs are better sealed than the "lower" hubs or simply more complicated to service?
    Feeling Good by David Burns

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    Tourist, thanks for responding. Your reply made it in while I was typing mine. So you have used M770 hubs and haven't had any problems? Great!

    Yeah, I can google "XT M770 failure" and get a few hits. Do me a favor and google "Rohloff failure" and see what comes up - lots more hits. And yet the Rohloff is the reliability darling of the touring set. Hmmm...

    You selected M756 hubs for your touring bike because you "took it as an endorsement" that because Surly equipped the BD with these hubs, and the BD is a cargo bike, that they must be stronger, right? Perhaps you should have considered that Surly used M756 hubs on the BD because the BD is equipped with Avid BB7 disc brakes with 6 bolt rotors and the M756 was the last XT hub to come with 6 bolt I.S. mountings (newer XT are Centerlock). Again, correlation does not imply causation.

    If we took what Surly equips its bikes with as a quality "endorsement" then LHT owners should be tossing the front and rear derailleurs because the 2012 LHT comes with a Sora FD and an LX RD (instead of the Tiagra and XT of previous years). Personally, I think that Surly is just trying to save a few bucks.

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    we be rollin' hybridbkrdr's Avatar
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    Quote Originally Posted by pexio View Post
    Tourist, thanks for responding. Your reply made it in while I was typing mine. So you have used M770 hubs and haven't had any problems? Great!

    Yeah, I can google "XT M770 failure" and get a few hits. Do me a favor and google "Rohloff failure" and see what comes up - lots more hits. And yet the Rohloff is the reliability darling of the touring set. Hmmm...

    You selected M756 hubs for your touring bike because you "took it as an endorsement" that because Surly equipped the BD with these hubs, and the BD is a cargo bike, that they must be stronger, right? Perhaps you should have considered that Surly used M756 hubs on the BD because the BD is equipped with Avid BB7 disc brakes with 6 bolt rotors and the M756 was the last XT hub to come with 6 bolt I.S. mountings (newer XT are Centerlock). Again, correlation does not imply causation.

    If we took what Surly equips its bikes with as a quality "endorsement" then LHT owners should be tossing the front and rear derailleurs because the 2012 LHT comes with a Sora FD and an LX RD (instead of the Tiagra and XT of previous years). Personally, I think that Surly is just trying to save a few bucks.
    Wow, they downgraded to Sora for the FD? Fender was acquired once and when the quality of their guitars went down so did their business. I thought the XT parts on an LHT was a reason to buy it, so people could save money on a build. This could encourage people to do their own build. It's true people view the FD as less crucial for shifting though.

    OK, you may continue your XT hub debate... (hehe)
    Last edited by hybridbkrdr; 10-20-11 at 11:01 AM.
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    "I'd like to see some real data points regarding this alleged "XT problem" and not the "concern"-mongering, "Some say.."-ing, and internet folklore regurgitating that seems to accompany this topic whenever it's raised."

    I wouldn't, what would the single data point of one user tell us that you wouldn't dismiss with the thought it was an outlier or just bad maintenance. Some of the reasons for Rohloff failure are from the same kind of cause. It wasn't actually designed for touring use, and quite transparently, on the basis a hundred or more years of touring bikes, the MTB strategies used to build the Rohloff lead to some weak point. I do think it is rational to go on track record (tells against companies that are constantly innovating) and on the basis of design. Experience alone will not always be the reliable guide. Also it is a different fault in logic to the one that you point out to assume that because a material is acceptable in one use, it will therefor work in others. Like aluminum ball bearings would not be a good idea just because the material works in handlebars.

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    Senior Member campylover's Avatar
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    Will you be doing any 4 foot drop-offs with your bike? I think the XT's will be fine.
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    we be rollin' hybridbkrdr's Avatar
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    Does anyone know if the Deore, LX and XT hubs are all coated with borozon?
    Feeling Good by David Burns

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    Quote Originally Posted by hybridbkrdr View Post
    Does anyone know if the Deore, LX and XT hubs are all coated with borozon?
    In the past, Shimano has claimed borozon-hardening on only its premium lines, specifically XT, XTR, Ultegra and DA. Lately their product descriptions make no mention of it, so perhaps its been discontinued, expanded to all products, or they've decided it's an ineffective marketing point and chose to not advertise it. Maybe the limited success of third-party marketing of "ceramic" bearings has effected their decision to use or advertise borozon (which is a ceramic too).

    Although borozon has been used successfully for years in mining and tooling applications, I'm not sure the benefits are significant in the case of MTB hubs used for touring. To most cyclists it's simply pixie dust that helps them justify paying 100% more for a hub they want that's probably only 1% better.

    I've got 7,000 miles on a non-borozon Deore hub so far, with no sign of wear. My best performance on XT hubs are 22,000 miles, but they started developing an erosion track at about ~17,000. Ask me again in 2 years and I'll be able to make a more informed comment on Deore vs XT hub bearing race wear.

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    Quote Originally Posted by seeker333 View Post
    Ask me again in 2 years and I'll be able to make a more informed comment on Deore vs XT hub bearing race wear.
    By then they will have changed it again, and we can start the meaningless process of tracking the performance of their hubs again. They are good though, but it is tough to track a moving target.

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    we be rollin' hybridbkrdr's Avatar
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    Quote Originally Posted by seeker333 View Post
    In the past, Shimano has claimed borozon-hardening on only its premium lines, specifically XT, XTR, Ultegra and DA. Lately their product descriptions make no mention of it, so perhaps its been discontinued, expanded to all products, or they've decided it's an ineffective marketing point and chose to not advertise it. Maybe the limited success of third-party marketing of "ceramic" bearings has effected their decision to use or advertise borozon (which is a ceramic too).

    Although borozon has been used successfully for years in mining and tooling applications, I'm not sure the benefits are significant in the case of MTB hubs used for touring. To most cyclists it's simply pixie dust that helps them justify paying 100% more for a hub they want that's probably only 1% better.

    I've got 7,000 miles on a non-borozon Deore hub so far, with no sign of wear. My best performance on XT hubs are 22,000 miles, but they started developing an erosion track at about ~17,000. Ask me again in 2 years and I'll be able to make a more informed comment on Deore vs XT hub bearing race wear.
    Well, I did read a message a while back from someone claiming he compared Deore hubs to (if I remember correctly) Dura-Ace (or minimum 105, not completely sure) with 20 years of use and said the road hubs were very smooth while the Deore hubs, not as much. But he said the Deore was ridden much rougher on a mountain bike.

    No one attempted to answer my earlier question as to why there are more parts next to the bearings of XT hubs (as per technical document drawings) and if it really represents an advantage or not.

    I really think Shimano should at least attempt to list detailed descriptions on their site for parts. I mean who can tell when a hub has a steel axle and an aluminium one?

    I'm also puzzled by the number of bearings. When I look at technical documents on dynamo hubs, the number of bearings varies but seems to be higher in the higher-end dynamo hubs. If larger bearings were really better at carrying a larger load, why would they use smaller bearings on higher-end parts? Ah well, maybe people don't have the anwers but wondering anyway.
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    Senior Member Doug64's Avatar
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    The XT hubs are not complicated. The seal pops out and is not as fragile as the tech documents would have you believe. Just remember what side goes toward the canter.

    Here is a good discussion about bearings. It is easier to replace them when servicing the hubs than to clean the old ones. I clean them for a couple of services, and then replace.

    http://www.parktool.com/blog/repair-...ramic-bearings

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