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Thread: Frame flex?

  1. #1
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    Frame flex?

    I keep dropping my chain and yesterday I slammed my knee so hard onto my fork crown that I nearly picked my bike up and hucked it off a cliff. It's a 2012 Giant XTC 29er Aluminum frame and it flexes like a gay bodybuilder at a nude beach. The build is good with a Hive SS crankset and WI Eno Ecc rear hub and the Trials freewheel, bombproof. At first I thought it was the hub slipping so I sanded and knotched the dropouts just to be safe. Then I though it was my freewheel, which was a standard one but I replaced it with a $100 fancy schmancy WI trials one with 1 million teeth engagement and a rattlesnake inside. Then I thought it was the chain which was an 8-speed but I replaced it with the Sram singlespeed. Then I thought it was my alignment which was maybe .2 mm off so I went both ways with it a couple steps trying it after each and even put my chainring on the outside of the crank and tried that which was much worse. I got some custom shims and it's now maybe a red headed butt hair off at most! Basically, I've tried everything but replacing the frame. This entire build is only a few months old and less than 300 miles on it.

    If I stand on the pedal with the front brake applied I can get the chain to loosen up and get about an inch and a half of freeplay. I can take it off the freewheel if someone is standing on it. I showed this to my LBS and they pretty much agree that the frame just can't handle single-speeding but they were also the ones who recommended this frame to me (which does handle amazing!). Now they are telling me to get a SC highball alu because it is intended for SS'ing but at this point i've lost some confidence in their opinion. They are going to sell me the highball at cost to make up for a bad recommendation which is cool of them but is that aluminum frame going to be any better? Are they full of ****? Do I just need to suck it up and get a steel/ti/carbon SS specific frame? Anyone want to buy a Giant XTC 29er M frame and an eccentric hub? Any good recommendations for a Medium 29er SS frame for a 100mm fork?

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    It is very true, and IMO, a common cause of chain drop - frame flex that is.

    Before I pull the trigger on my next SS frame I want to know for sure the frame I'm getting is not a noodle.

    The SC is in the running. I also figure that Niner has been making the One 9 for so many years they'd hopefully have it dialed by now.

    Let us know what you come up with.

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    The SC frame might be a little better, but if I were in your shoes I would ditch the thought of aluminum. Steel is real, and it will give you the best bang for your buck, but carbon and Ti are both beautiful options also, if you've got the coin. Ti frames have been known to be a little noodly, though I have no experience with Ti so take that FWIW. As for a recommendation, I would go for a Salsa El Mariachi. Steel, great with 100mm fork, geo is dialed, alternator dropouts get rave reviews, and it won't break the bank. Niner SIR9 is another option with a little racier geometry, EBB, and slightly higher price tag. I don't know which would be closer in geometry to your Giant though.

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    What kind & size cog you riding? I had a problem awhile ago where I was vacationing I spent three days of riding and was so spent on the fourth day that I threw on my biggest cog which was a 21t from an old 8speed casset I took apart. the damn thing kept jumping off any time I hit a hill and had to push hard. Nothing would work to keep it on, later the following month I put it on again and it kept coming off no matter how tight or aligned the chain was but when I put any of the other single speed specific cogs on it worked fine and never came off. also note that it seemed to work fine when I used an 18t cog form the same old casset, so either the 21t cog was damaged or being a bigger tooth it was just enough flex to jump off a skinny short teeth cog. I do know most single speed cogs have longer teeth.
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    If you are flexing off the rack Al, I don't think you'll fair any better with steel or Ti. Maybe if you went custom the builder could design more stiffness into the frame. I think your best bet is carbon.

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    Stiffness comes from design rather then material.

    Steel, Aluminum, Ti, or Carbon can be made as stiff or flexible as the designer wants. In particular for a given tube diameter steel will be stiffer then aluminum or Ti. In order for an aluminum bike to be stiff the tubes need to be larger diameter because aluminum is not as stiff. Steel bikes with 42mm downtubes and oversized chainstays are crazy stiff.

    With 29ers an added challenge is the tight area behind the bottom bracket where the rear tire, chainring, and chainstay all compete for space. If the cross section of the chainstay is reduced the bike will become more flexible unless an extra thick tube and/or a yoke is used the bike may lack stiffness.

    You also may want to run a 22 tooth or larger rear cog and the corresponding chainring to make your existing and future bikes less susceptible to chain tension issues.

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    Funny - I think the (steel) El Mariachi was THE noodliest bike I have ever ridden.

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    Wouldnt running a tensioner fix the problem?

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    For all around riding, I liked my Nimble 9. My One 9 is great as well. Both fairly stiff frames. Air 9 Carbon is stiffer than both.

    Quote Originally Posted by bugshield View Post
    Funny - I think the (steel) El Mariachi was THE noodliest bike I have ever ridden.
    Which El Mar? I haven't ridden the older version (853 tubing), but the new ones aren't bad.

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    Iv'e got the exact same setup with no problems. Im running a 32-20 wi hubs and a wi freewheel 9 speed chain and a salsa ss chain ring. I did have my LBS custom build my wheels so im not sure if having the wheels dished for ss has anything to do with your issues. The guy who built my wheels really knows his stuff when it comes to custom setups like this. But i will take any pics of my rig that you need so we can compare and get to the bottom of this!




    I just remembered that Wi has a funky chain line and When i was researching chain line i had to do something funky to make it work. It was something with spacers on the bb or. Ill take a look at my bike tomorrow.
    Last edited by Utilityman; 12-02-2012 at 09:23 PM.

  11. #11
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    Quote Originally Posted by ridefast84 View Post
    Iv'e got the exact same setup with no problems. My chain fell off the first ride but i had the chain too loose and put it on a little tighter. I love the ride and the xtc just rails corners and climbs awesome! The geometry is perfect for me! I kinda wanna sell my lynskey and get the carbon xtc. Im running a 32-20 wi hubs with a wi freewheel and a 9 speed chain. I did have my LBS custom build my wheels so im not sure if having the wheels dished for ss has anything to do with your issues but i will take any pics of my rig that you need so we can compare and get to the bottom of this!
    What crank are you running to get the chain line right for that WI hub?
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    Shimano lx. If I remover right I was 2mm off when I installed with 2 spacers on the drive and one on the non drive bb. So I put 2 on non drive and one on drive.

    I need to look at my bike to be 100% sure, I could be thinkin of another build. Ill verify tomorrow

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    Haha, that's funny, we have pretty much the same build. I'm running a 32-18. Yes I could alleviate all this by running a tensioner or one of those sliding chain guides but that would defeat the whole purpose of the eccentric hub and all the money I spent on it..and I don't like clutter, and I'm not going to run a 39t chainring so I can run a 22t freewheel, which would be another $100 just for the freewheel!

    The flex is very noticeable on my frame at least, if you hold your front brake and pedal down how much slack can you put in the chain? I'll try to get a pic or something tomorrow to show but I go from really tight to REALLY loose, granted i'm built like a damn mule and put down some extreme torquage but I don't feel that should be happening regardless. I'm not necessarily opposed to "flex" but I am strongly opposed to chains coming off when I'm mashing up a hill. I dropped it off at the shop today and they are going to play with the alignment and test ride it tomorrow. I dropped off a 6 pack of some local DBA as well in case the test rider slams his face on the stem or his knee on the crown...or both. Hopefully I'll hear some good news like the alignment went out or something but I've pretty much concluded my investigations and am fairly certain it all comes down to frame flex. I hope not as I just built that damn thing but I can't see what else it would be. Here's mine (pic is old hub):



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    That freewheel looks very small.

    How many teeth do you have in the back/front? From the way it looks, that may be your problem. Put a 20 tooth or larger freewheel on and I bet your problems will be gone. You can run a larger chainring to give you the same effective gear. The larger your combo is the better your bike will do in terms of chain tension issues.

    Also check your freewheel. I had an ACS freewheel on my first singlespeed and it was really bad with slop and play in the system. Compared to a WI freewheel or a normal cassette hub the cheap china made freewheel was penny wise and pound foolish because it wore out in a matter of weeks.

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    Quote Originally Posted by febikes View Post
    That freewheel looks very small.

    How many teeth do you have in the back/front? From the way it looks, that may be your problem. Put a 20 tooth or larger freewheel on and I bet your problems will be gone. You can run a larger chainring to give you the same effective gear. The larger your combo is the better your bike will do in terms of chain tension issues.

    Also check your freewheel. I had an ACS freewheel on my first singlespeed and it was really bad with slop and play in the system. Compared to a WI freewheel or a normal cassette hub the cheap china made freewheel was penny wise and pound foolish because it wore out in a matter of weeks.
    Slow down and the read the thread. OP's last post answered your first question. His original post already mentioned he's running a WI trials with a gazillion points of engagement. There is zero wrong with his freewheel.

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    Based on the pic I'd suspect the chain isn't tight enough.

    I had problems before with an ebb where I sized the chain wrong on install because I wasn't thinking about the ebb. Another time with different gear combo on the same bike with the ebb it just wouldn't work with the gearing I chose. I had to choose between a half link or leaving the chain where it was at and installing a new front ring + one tooth. I chose changing the front ring +1 to a 33.

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    First check your chain line, second get the chain tight.

    Only out of interest mind and not a point what do you weigh?

    Aluminium frames are generally stiff + unforgiving as fook so I would suggest it is chainline and lack of tension.

    Good luck sorting it as you do not need dropped chains whilst trying to enjoy the wonder of singlespeed.

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    Quote Originally Posted by phsycle View Post
    Which El Mar? I haven't ridden the older version (853 tubing), but the new ones aren't bad.
    I don't want to take this thread off topic but 2012. A huge disappointment because I was flirting with a titanium El Mariachi.

    PS. Just so you don't have to ask the next obvious questions; I was 6' and 225-ish at the time. Frame was a large. I mash but not as bad with gears. Let's leave it at that for this thread.

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    Quote Originally Posted by FreeCoffee View Post
    (pic is old hub)
    I understand that you are not currently running that hub but in the pic the chain is SUPER loose to me. Maybe just a mock up or pre-adjustment in the pic and that's fine, but if your chain still looks like that you've found at least one problem.

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    As I said, that's an old pic, I've since updated both the chain and freewheel. I played with the alignment a little and got the chain tight, zero slack. I'm going to go for a couple hour ride and see what happens, hopefully I don't smash my nuts.

    ..I'm 5'7" 165-170lbs if you think that matters.

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    The chain is a little lose in that photo - but I've run them like that all the time and no drops on my cheap steel frames.

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    Did you put a SRAM PC-1 chain on there? If so, that is the most elastic chain I've ever used. Try a KMC chain double check the chainline....

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    Quote Originally Posted by wjphillips View Post
    Did you put a SRAM PC-1 chain on there? If so, that is the most elastic chain I've ever used. Try a KMC chain double check the chainline....

    That is bs. Whatever problems the OP is having a KMC chain sure isn't going to fix. That chain looks way loose in one of the pics but like SS said I've run them like that and still never dropped a chain.

    Seems weird but it does seem like something is up with that frame, especially since the shop agreed and it seems like Free Coffee checked most of the other boxes.

    I'm not saying that the chain couldn't be the problem, just that it isn't a brand problem.

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    I dunno. I used to love the PC-1 chain until I started having chain drop problems. I have track fork ends, and I kept tightening the chain but it would always pop off. It got so bad I had to tighten the chain after every ride. I switched to KMC and it works a lot better (for me). Chain hasn't popped off in over 600 miles.

    Another problem could be your front chain ring. If you pedal backwards, does the chain maintain its tension consistently? Are there loose spots then tight spots? That could cause the chain to pop off as well. You may need to re-align your front chain ring. You will never get it "perfect", but it could help. Large differences in tension could be the cause.

  25. #25
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    I have found old school BMX style wider chains work better than new 9 speed stuff...

  26. #26
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    I'm guessing there's a defect in the workmanship of the frame. It shouldn't flex like that under you weight, singlespeed or not. If it's flexing that much, the aluminum will fatigue fast and you'll risk a broken chainstay/bb cluster in no time.

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    Quote Originally Posted by textbookonewk View Post
    The SC frame might be a little better, but if I were in your shoes I would ditch the thought of aluminum. Steel is real, and it will give you the best bang for your buck, but carbon and Ti are both beautiful options also, if you've got the coin. Ti frames have been known to be a little noodly, though I have no experience with Ti so take that FWIW. As for a recommendation, I would go for a Salsa El Mariachi. Steel, great with 100mm fork, geo is dialed, alternator dropouts get rave reviews, and it won't break the bank. Niner SIR9 is another option with a little racier geometry, EBB, and slightly higher price tag. I don't know which would be closer in geometry to your Giant though.
    LOL. That's right. You should completely omit aluminum from your frame selections because it's not "real". Go ride your bike.

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    Quote Originally Posted by bugshield View Post
    Funny - I think the (steel) El Mariachi was THE noodliest bike I have ever ridden.
    true dat, I trained on a El for two years, that would be the last bike I would recommend for stiffness!

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    Quote Originally Posted by trevrev97 View Post
    true dat, I trained on a El for two years, that would be the last bike I would recommend for stiffness!
    Was it an older model, people seem to complain about the new one being too stiff?

  30. #30
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    I'm a bit curious that you're worried about flex and running CREST rims Honestly I only weigh about 175-180lbs geared and I got a Pro2/Crest front to try out and even after only riding mild trails I've decided the little bit of weight savings is not worth the lack of stiffness they have. Do yourself a favour and get some FlowEX or ArchEX and know for sure that the wheels are not going to be any part of a flex issue you may be having.
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    ^ I answered that earlier...
    Quote Originally Posted by FreeCoffee View Post
    I'm not necessarily opposed to "flex" but I am strongly opposed to chains coming off when I'm mashing up a hill.
    The wheels are great and I have a set of flow's on my other bike so I know what you are saying but rim flex is not going to be the issue that I'm having. My wheels are straight and true and my hub/freewheel combo is bombproof. The issue is the frame. Now the "fix" is me trying to compensate for the flex by messing with the alignment.....or buy a new frame, which makes my cool eccentric hub pointless, and more importantly could mess up my cool black/red/white color scheme I got going on

    I rode it yesterday and it fell off twice. The alignment was a little inward. I've since switched the chainwheel to the outside and so it's now a little outward. I rode it around my house on asphalt and couldn't get it to come off. I'm going for a climb after work to truly test it out but here's hoping. I'll update you guys with some pics and maybe some video showing how flexy this frame is...

  32. #32
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    In the OP you stated that you can get the chain loosen by holding the brake and standing on the pedal. That seems to me that something is slipping how is the wheel secured in the dropouts? O n my road bike I was having a problem with the wheel shifting to one side no matter how tight the quik release was I put on a diffrent one ,no more slippage.

  33. #33
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    FreeCoffee - I am slightly taller and slightly heavier..guess it would be proportionate in body size/frame. I can flex the mess out of carbon cranks, and have actually bent and broke chainrings, sheering the bolts out. So I know exactly where you're coming from....

    I would suggest running a "true" SS frame with sliders or EBB, you'd probably have better luck with a slider system..less creaking.

    I would suggest also running a stronger chainring like a Blackspire Veloce. They are stiffer than many other brands out there (at the expense of a few grams)

    As for your frame options, there are a lot of different routes you can go. Carbon is going to be stiff, but there are only a few out there that are SS, and fewer that have sliders....also the cost involved. Steel is going to send you in two directions for stock (non-custom) frames.....light, compliant, flexy or overyly stiff, heavy and ride like tank. Titanium in my opinion is the best (But expensive)...assuming you get the features that matter. 73mm BB, oversized downtube with a 44mm headtube for tapered fork. I have a Lynskey Pro29 SL and its amazingly stiff at the BB and headtube, but great compliance in the rear. I had a 2009 Pro29 and it was very flexy in comparison..but Lynskey beefed everything up for 2012.

    For aluminum, I am pretty sure that the Highball is going to be stiffer and work better than your XTC..or at least stiffer in the back end of the bike..equal stiffness in the front.

    I never really like the WI ENO solution for SS, it has to be spun around in a certain way for it to keep tension (which may also be the problem) and you always risk slipping and ghost problems that point elsewhere...IMO, if you're going to do SS, do it right with a real SS frame, and you alleviate a lot of problems.

    You may also consider a 10mm thru-bolt or DT Swiss RWS...there is a big difference in stiffness compared to the 9mm QR.

    I highly doubt it is your chain, but I've never had a problem with the SRAM PC-1 Nickel....$12 and a great long lasting chain.

    You have to remember...all this stuff is meant to work as a "System" so a little bit of flex in a few different places add up
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  34. #34
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    Quote Originally Posted by WarBoom View Post
    Wouldnt running a tensioner fix the problem?

    I used to run a non-vertical dropout with no tensioner. That was 40 years ago. Never worked well.

    Give me vertical dropouts with a guide or tensioner. Problem fixed..
    Last edited by 1niceride; 12-04-2012 at 05:53 PM.
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    Quote Originally Posted by 1niceride View Post
    I used to run a sliding dropout with no tensioner. That was 40 years ago. Never worked well.

    Give me vertical dropouts with a guide or tensioner. Problem fixed..
    You sure that "sliding dropout from 40yrs ago" wasn't just "horizontal dropouts?
    Sliders have a vertical dropout, and work infinitely better than any tensioner on the market!
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    Quote Originally Posted by 1niceride View Post
    I used to run a non-vertical dropout with no tensioner. That was 40 years ago. Never worked well.

    Give me vertical dropouts with a guide or tensioner. Problem fixed..
    fixed.. point is the tensioner makes up for elasticity in the chain stay. No matter the dropout config..
    lean forward

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    There are no weight limits on the xtc or statements that you can't run the bike ss or ride up hills in certain gears. Even guys on geared setups mashing up hills in the same ratio you have are not slipping the chain. Theres got to be an issue with the lbs who built it or your hub or even the frame.

    Ill bet your Chain line is way off wi hubs require a 47.5mm chain line and from researching your hive cranks are set up for a 50.9mm. Thats like 3.5mm your chain line is off. Shimano cranks have a 47.5mm chain line! Im just sayin I think your cranks are the problem. If you have another bike with shimano cranks swap the cranks and see if there is any change.

    I was wrong about doing something funky, that was another build. I did have to space the rear brake with brake spacers and a different disc brake mount. But thats it.
    I checked my xtc and eno hub and I am solid. I dropped the chain on the 1st ride and that was my error from setting it up to loose.

    Best chain tensioner on the market!
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    ridefast, you give me hope! I love this frame and really don't want to toss it. I dropped it 3 times tonight so the outer position is definitely worse. When I had it mounted on the inside we only had maybe a 1mm spacer on it. I thought I read somewhere that it was the same as the middle Shimano but if it's 50.9mm than I need to go back to the drawing board because I've been off the whole time then.

    In the OP you stated that you can get the chain loosen by holding the brake and standing on the pedal. That seems to me that something is slipping how is the wheel secured in the dropouts? O n my road bike I was having a problem with the wheel shifting to one side no matter how tight the quik release was I put on a diffrent one ,no more slippage.
    It's not slippage, it's flex. The chain does get loose by holding the brake and standing on the pedal but it pops right back to tight when released. I thought it was slipping at first too but I've pretty much covered all the bases on that side. Waiting for the wife to get home and I'll try and get some pics showing this difference.

    Thanks for all the help everyone. I really don't have any reason to buy a new frame other than the chain coming off so if I can get it figured out I'll be stoked.
    Last edited by FreeCoffee; 12-04-2012 at 09:06 PM.

  39. #39
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    Quote Originally Posted by FreeCoffee View Post
    ridefast, you give me hope! I love this frame and really don't want to toss it. I dropped it 3 times tonight so the outer position is definitely worse. When I had it mounted on the inside we only had maybe a 1mm spacer on it. I thought I read somewhere that it was the same as the middle Shimano but if it's 50.9mm than I need to go back to the drawing board because I've been off the whole time then.

    It's not slippage, it's flex. The chain does get loose by holding the brake and standing on the pedal but it pops right back to tight when released. I thought it was slipping at first too but I've pretty much covered all the bases on that side. Waiting for the wife to get home and I'll try and get some pics showing this difference.

    Thanks for all the help everyone. I really don't have any reason to buy a new frame other than chain slippage so if I can get it figured out I'll be stoked.
    The 2010 version of that frame had what was IMO an underbuilt rear end, especially the seat stays. I could hold the rear brake on and stand on the crank arm in a low gear and watch the frame twist and bow from the brake mount all the way up to the seat tube. As well, I could ride that bike in a big gear, seated, pedaling very hard, and look down and see the entire rear end wrapping up like a big S. Now I never felt like it got in the way when actually riding the bike, but none of that would be good on an SS.

    Chainline...you said you know your front CL is 47.5mm to match the rear hub? Man, that has to be spot on too. Just asking again. Measure it. Get a nice steel ruler with accurate markings and measure from the center of the seat tube to the center of the tooth on the chainring. Very few cranks other than WI cranks are 47.5mm...the old Shimano standard for the middle ring with a proper BB length. I was trying to talk WI into making a more modern hub width to get the killer freewheel in a useful place so it would run on the more typical 50+-ish mm CL.
    Last edited by mtroy; 12-04-2012 at 09:10 PM.
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    What style bb do you have on the xtc? Is it the press fit style? Ive never seen one up close so forgive me if I am wrong here. But on a standard 73mm bb this will change the chain line. If you have a spacer on the drive side of the bb take it off and put it on the non drive side. That spacer might make a difference in moving the chain line inward.

    Really what you need is another crankset. Heck see if the lbs has a shimano crankset you can borrow.

    Im no expert here just sayin where i would start.

  41. #41
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    Chainline...you said you know your front CL is 47.5mm to match the rear hub? Man, that has to be spot on too. Just asking again. Measure it. Get a nice steel ruler with accurate markings and measure from the center of the seat tube to the center of the tooth on the chainring. Very few cranks other than WI cranks are 47.5mm...the old Shimano standard for the middle ring with a proper BB length. I was trying to talk WI into making a more modern hub width to get the killer freewheel in a useful place so it would run on the more typical 50+-ish mm CL.
    You know that saying about assuming things? I thought it was at 47.5mm stock so initially when I started having problems and messing with my chainline I brought the chainring in 1mm which I thought would have made it 46.5mm but apparently it was 49.9mm. I then went the other way and moved the chainring to the outside and it's probably around 52mm or so now (which explains why it dropped more today). I'm more of a learn-by-f*ing it up kind of guy rather than a measure-twice-cut-once kind of guy.

    ridefast - It's an e*thirteen specific bb, no spacers to move around, and the whole build started off around this crank so no, I'm not going to try out some new cranks, I'll replace the frame before that. I found a pic of someone who spaced out the freewheel from the eno hub so I'm going to try spacing the freewheel out 2mm and put the 1mm spacers back on the chainring and see how that goes. Hopefully better than today...

  42. #42
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    Good call on the freewheel spacers. Your problem will be solved.

  43. #43
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    Quote Originally Posted by FreeCoffee View Post
    You know that saying about assuming things? I thought it was at 47.5mm stock so initially when I started having problems and messing with my chainline I brought the chainring in 1mm which I thought would have made it 46.5mm but apparently it was 49.9mm. I then went the other way and moved the chainring to the outside and it's probably around 52mm or so now (which explains why it dropped more today). I'm more of a learn-by-f*ing it up kind of guy rather than a measure-twice-cut-once kind of guy.

    ridefast - It's an e*thirteen specific bb, no spacers to move around, and the whole build started off around this crank so no, I'm not going to try out some new cranks, I'll replace the frame before that. I found a pic of someone who spaced out the freewheel from the eno hub so I'm going to try spacing the freewheel out 2mm and put the 1mm spacers back on the chainring and see how that goes. Hopefully better than today...
    Ah soooo....a light breaks through! A crank is a crank is a crank IMO unless it is truly an anchor or just rubbish. The frame is the heart of the bike. Good luck with the spacers. I considered doing that with mine but went another direction.
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  44. #44
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    Quote Originally Posted by ridefast84 View Post
    Good call on the freewheel spacers. Your problem will be solved.
    Don't think so. With as much frame flex as the OP describes, it's likely he'll be dropping chains irrespective of chainline. Hammering up a bumpy climb will do it.

  45. #45
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    Quote Originally Posted by zaskaranddriver View Post
    Don't think so. With as much frame flex as the OP describes, it's likely he'll be dropping chains irrespective of chainline. Hammering up a bumpy climb will do it.
    Yeah, that's what I'm afraid of too but I'm trying to stay positive and keep telling myself that if someone else has the same bike and it works good then so should mine. At least after this final attempt at getting the chainline correct I'll be able to say I crossed off everything except for the frame...it'll make it easier to convince the wife that I need yet another one

  46. #46
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    Just go buy and a cheap steel single speed frame and be done with it - toss the Ai POS in the recycle bin. You can get a solid and highly regarded On One for less than $250 shipped.

  47. #47
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    Free C,
    As another SS-er with an e-13 I understand just how important it is to measure chainline.
    Once dialed, you can resolve the tension issue. The pic shows it being way too loose,
    and if it were my #210, while perfectly aligned I would not trust it. IME popping the chain is a combo of these two,
    plus a possible out-of-round chainring, and probably NOT frame flex.

    Before confronting wifey for a new SS frame, check the chainring roundness, set chainline, and reset tension,
    which could be more painful than smacking your nutz on the tt..

  48. #48
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    Quote Originally Posted by SS Hack View Post
    Just go buy and a cheap steel single speed frame and be done with it - toss the Ai POS in the recycle bin. You can get a solid and highly regarded On One for less than $250 shipped.
    Geometry, fit and rider preference be damned!

  49. #49
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    Quote Originally Posted by OneBadWagon View Post
    Geometry, fit and rider preference be damned!
    I don't think I said that ... the OP wanted a medium SS frame and I offered an idea (lots of other options). I guess it's better to keep throwing good money on top of bad and keep buying fancy hubs and posting on the internet to solve his problem?

    I'm the same weight as this guy (a little taller) and never drop chains, no matter how lose I run them. I also ride in a very mountainous area.

  50. #50
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    Spending money replacing things that arent broken or troublesome is bad troubleshooting and isn't the bikes fault.

  51. #51
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    Chainline <.2mm off



    Chain is tight, really tight.




    ...and when I step on the pedal it gets loose, really loose




    I rode it back from the shop on a little bit of fireroad and a lot of asphalt and everything was fine. I'll try and get a proper ride in tomorrow and see how that goes. I'm not confident yet.

  52. #52
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    Ya got that empty hole lookin right at ya...
    lean forward

  53. #53
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    1. You'll observe more seat stay flex if you hold the brake and stand on the pedal. You're doubling the work load on the seat stays because the brake is transferring torque into the non-drive seat stay in this scenario which wouldn't happen while you're riding. E.g., the frame doesn't flex this much while you are riding.

    2. Can you use a spacer to to move the free wheel out about 1mm? IMO, your chain line is off a bit, and since you said yourself that moving the chain ring to the outside of the crank made the issue worse and adding a spacer to the inside of the chain ring on the inside of the crank made the issue better, it seems pretty obvious to me that it's worth trying to move the chain line further inboard on the front/further outboard on the rear and see if that sorts it for you. It's hard to tell from the pic, but I think your chain line is off by more than 1mm.

    FWIW, my frame flexes more than yours does, I run my chain looser than you do, and I've never dropped a chain. *knock on wood*

  54. #54
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    Quote Originally Posted by solo-x View Post
    2. Can you use a spacer to to move the free wheel out about 1mm? IMO, your chain line is off a bit, and since you said yourself that moving the chain ring to the outside of the crank made the issue worse and adding a spacer to the inside of the chain ring on the inside of the crank made the issue better, it seems pretty obvious to me that it's worth trying to move the chain line further in the further inboard on the front/further outboard on the rear and see if that sorts it for you. It's hard to tell from the pic, but I think your chain line is off by more than 1mm.
    That's what I just did, there's a 3mm spacer in the rear spacing out the freewheel and some thin washers under the chainwheel pushing it farther inwards. According to the published #'s that puts it at roughly +/- .2mm off. It's just a slightly angled pic. It's reassuring that you say your frame flexes more and you run your chain loose but my confidence is already pretty low. I'll see tomorrow...

  55. #55
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    The way I see it there are two places where the flex is primarily occurring--either in the DS chainstay or the DS dropout. Contrary to popular SS lore, you can put more torque to the ground through the low ratios of a geared setup, so I can't imagine that the Giant engineers didn't dial out the chainstay flex (since that flex would lead to rapid Al fatigue, warranty claims, and lost profits). Therefore I'm thinking it's the torque that the eno system puts on the dropout for which Giant didn't account. One way to test this theory is to put a regular wheel on the bike and see if you get as much (additional) chain droop under torque.

  56. #56
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    In the first picture you posted, do you see how the chain is all the way up against the side plate on the inboard side? That's just waiting to catch one of the cog teeth on the chain and skip. It should be centered on the rollers.

  57. #57
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    Yeah, I see what you're saying. I'll try and find some thicker spacers for the chainwheel, I don't want to go anymore on the freewheel spacing and risk not being on enough threads. How it is now seems good so far on the way to work, the way back is uphill and I'm going to take the long way up a steep rocky section so we'll see how that plays out, I'll swing by the shop and see if they have some spacers though. Appreciate all the help, I am still fairly new at the MTB stuff, I'm a moto guy whose never had to deal with chainline issues.

  58. #58
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    FC,
    It appears that the freewheel is too far outboard. (Pic 1 shows cog teeth contacting chain off-center towards inside) Eliminate a shim, or to until it is centered.
    Know it's frustration, and hope this helps.

  59. #59
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    Quote Originally Posted by OneBadWagon View Post
    In the first picture you posted, do you see how the chain is all the way up against the side plate on the inboard side? That's just waiting to catch one of the cog teeth on the chain and skip. It should be centered on the rollers.
    This is what I feel as well. If the teeth aren't centered on the rollers, you'll be more likely to have problems. Since you've already noted that moving in the direction I suggested was making the issue less pronounced and moving the other direction made it worse, then I take that as further supporting evidence that my theory is close to right.

  60. #60
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    Quote Originally Posted by Flyin_W View Post
    FC,
    It appears that the freewheel is too far outboard. (Pic 1 shows cog teeth contacting chain off-center towards inside) Eliminate a shim, or to until it is centered.
    Know it's frustration, and hope this helps.
    Want to try that again?


    I wonder if the previous poster who showed his XTC chainline was using an older frame with threaded bb, and had simply moved the drive side spacer over to the non-drive side. According to the numbers, you've got almost 1/8 of an inch of difference in listed chainlines.

  61. #61
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    Yes I do have a threaded bb, and I do have the spacer on the drive side. I am running cranks that give the same chain line as my rear hub. This is the reason i don't have chain line issues. I was suggesting op to slap on a set of shimano cranks just to see if his problems went away so he can eliminate there being something wrong with the hub/freewheel or frame. Just so he can get to the root of the problem and know for sure where to go from here.
    Sounds kind of expensive to get rid of the rear wheel and frame just to go buy another ss frame and wheel when he already has a sweet setup!

  62. #62
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    Quote Originally Posted by ridefast84 View Post
    Yes I do have a threaded bb, and I do have the spacer on the drive side. I am running cranks that give the same chain line as my rear hub. This is the reason i don't have chain line issues. I was suggesting op to slap on a set of shimano cranks just to see if his problems went away so he can eliminate there being something wrong with the hub/freewheel or frame. Just so he can get to the root of the problem and know for sure where to go from here.
    Sounds kind of expensive to get rid of the rear wheel and frame just to go buy another ss frame and wheel when he already has a sweet setup!
    On a 68mm shell, there are normally 2 spacers on the drive side and 1 on the non-drive side. By shifting one from the drive side to the non-drive side, you've shifted your chainline inboard 2.5mm. (you could have also moved all 3 to the non drive side, which would be closer to perfect chainline. The original poster may have this option. I'm not sure how thick the BB spacer is listed here, nor whether or not it can be switched to the NDS, but it's worth a look!
    http://www.e13components.com/setup_i.../bb_92_web.pdf

  63. #63
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    Yea I have a 73mm bb with one spacer installed. Not sure how press fit bb stuff works yet and I am going to avoid them for as long as I can. I did exactly what you are talkin about on a friends bike and it worked perfect.

  64. #64
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    Quote Originally Posted by bugshield View Post
    Funny - I think the (steel) El Mariachi was THE noodliest bike I have ever ridden.
    Here on MTBR, some people describe that as being "compliant" or "not harsh"
    Mind your own religion.

  65. #65
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    Thanks for the help and opinions but I've had my last straw with this piece of ****. You can see the outline of my compression adjust knob!

    The chainline has been moved in .2 mm increments both directions trying to find the "sweet spot" but it doesn't exist. I've had 3 shops look at it, 2 say it's got to be the frame, 1 said that the Eno hub is well known to have "ghost issues". I'm over it. I'm now in the market for a SS steel frame and a new rear hub. Let me know if anyone's interested in a medium Giant XTC frame or a WI Eno hub and Trials freewheel in a 18t, less than 200 miles on all of it.

  66. #66
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    Quote Originally Posted by FreeCoffee View Post
    Thanks for the help and opinions but I've had my last straw with this piece of ****. You can see the outline of my compression adjust knob!

    The chainline has been moved in .2 mm increments both directions trying to find the "sweet spot" but it doesn't exist. I've had 3 shops look at it, 2 say it's got to be the frame, 1 said that the Eno hub is well known to have "ghost issues". I'm over it. I'm now in the market for a SS steel frame and a new rear hub. Let me know if anyone's interested in a medium Giant XTC frame or a WI Eno hub and Trials freewheel in a 18t, less than 200 miles on all of it.

    That sucks man! But with this type of hub or a "tensioner". It will never work as flawlessly as a SS frame. Because you're using modified equipment to change something to something else...there will always be setbacks

    If I may make a suggestion, not sure about your budget, but I'd look for a frame with a "Slider system" Where the brake mount is fixed to the same part that connects to the axle. There are no adjustments to be made. Pull it back for tension, lockdown the 4 bolts and be done with it! EBBs are ok, but from my experience, everytime you adjust the EBB, you have to adjust your seat or seatpost to compensate for these geometry changes. EBBs have also been known to squeak, or make noise...not the case with sliders.

    There are some good bikes out there with good sliders to choose from:
    Soma Fab. Juice
    Kona Honzo
    Canfield Nimble 9
    Salsa El Mariachi

    Also my preference is a rear wheel with a freehub meant for gears, but with the use of spacers. This may contradict me saying its not a "true" singlespeed, but I have not noticed a difference in performance with wheel dish, and in special situations, you can change it to being a geared bike when you need it. It just expands the capability of what you can possibly use the bike for.

    Just a tip, find a brand of cogs you like and stick with it! This way you don't have to change the spacing on the freehub, everything should line up perfectly every time. I use niner cogs because they seem to lasting a long time, not very expensive, strong, light, and all the same width across the line.
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  67. #67
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    Check all the teeth on the chainring, and also inspect the ring itself make sure it is not bent. The flex you get while standing on the pedals when the bike is stationary with brakes applied is going to be alot more than the flex you get while actually riding the bike. One bent tooth can cause you to drop your chain.

  68. #68
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    Just get the steel frame and report back. Good luck.

  69. #69
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    Good news is the hub can be converted to a standard hub so all I'm replacing is the frame. I have a buddy who's going to let me ride his SC highball tomorrow. I know I said I wanted steel but the shop feels bad about selling me a frame that I am afraid to ride so they are going to EP me out a frame and I can get a highball pretty damn cheap...and I'm really liking that new tension system they got.

    I was really interested in the Nimble 9, I really like those geometry #'s but I almost feel that it's too aggressive for the amount of climbing and distance I do and I have a tapered fork and their new frames that do accept that aren't going to be available till March. I think the El Mariachi is too stretched out for my liking and I refuse to buy a Kona. I like the #'s of the highball, it's really close to what I know I already like just a bit steeper head angle which is a plus to me. I'm kind of a weight weenie with this thing anyways but who knows, I'll probably change my mind tomorrow

  70. #70
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    I hear those highballs are pretty sick! Check out these tensioners, they are the best ive seen!
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