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Chain Rubbing On Inside Of Largest Chain Ring?

SoniSoni Posts: 1,217
edited March 2010 in Workshop
I've been experiencing chain rub and initially thought it was rubbing on the front derailier cage, however upon closer inspection, its not the derailier cage at all, its actually rubbing on the inside of the largest front chainring.

I have a tripple, and its only when in the smallest rear ring and on the middle front chain ring, the chain rubs on the inside of the largest chain ring.

How can i correct this?
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Posts

  • AnonymousAnonymous Posts: 28,799
    You can't.

    You should be in the big ring and on a bigger sprocket instead.
  • SoniSoni Posts: 1,217
    NapoleonD wrote:
    You can't.

    You should be in the big ring and on a bigger sprocket instead.

    Oh i see :oops:

    I think i recall seeing some months ago a video teaching on how to use gears, as daft as it sounds, riding a bike isn't quite as simple as some believe....

    I'll take a look over the net to see if i can find that video again, it teaches you how to move up the gears correctly....
  • You should be able to use all the rear sprokets whilst in the middle ring although big/big and small/small is to be avoided. It sounds to me like your BB axel is too short. Have you got the recommended axel length for your chainset?
    I have only two things to say to that; Bo***cks
  • SoniSoni Posts: 1,217
    You should be able to use all the rear sprokets whilst in the middle ring although big/big and small/small is to be avoided. It sounds to me like your BB axel is too short. Have you got the recommended axel length for your chainset?

    Hi Mate, interesting, as a mate came over tonight, the first time we've been out riding together and he has Sora rear and front mech, i have 105 on the rear and Sora on the front, and both out bikes are tripples.

    His gears were perfect, he's had the bike 3 years and has never done ANYTHING to it, hasn't ever even touched the gears.

    Out of all his gears, only 2 were rubbing on the front derailer, these were the smallest and the one next to it on the rear, whilst he was on the smallest chain ring on the front.

    I'm really dissapointed with mine, the gears have NEVER worked right since new.

    Also, as well as it rubbing on the front derailer, its rubbing on the inside of the largest chain ring when on the smallest and the one next to it on the rear when on the middle chain ring....

    How can we both have tripples and his be so much better than mine?
  • The problem is worse on smaller bikes as the chain run is shorter. You can adjust it as much as you like but on some bikes you just cant use the small chain ring with some of the smaller cogs.
  • SoniSoni Posts: 1,217
    OK maybe i should explain myself better.

    The problem i've got is that the chain is rubbing on the inside of the largest front chain ring when on the middle front chain ring in the 1st, 2nd, and 3rd smallest cogs on the rear,,,,,

    This shouldn't happen surely - its a straight line almost!
  • You're right, that shouldn't happen.

    I'm struggling to think why the rubbing is that extreme on a triple. You might get a little bit when you're on the smallest cog if you've got a small frame but the other cogs should be okay. As a long shot...... are you running a 9 speed chain on a 10 speed chainset? I think (and I'm happy to be corrected) a 9 speed chain is slightly wider so that might be causing the rubbing.

    If it's not that, try putting it in the offending cogs and looking along the chain line to see how straight it is. Something may be out of alignment.
  • Thats natural mate, it will happen when you are on the small ring and riding the small cog
  • SoniSoni Posts: 1,217
    Thats natural mate, it will happen when you are on the small ring and riding the small cog

    It isn't, when riding the small ring on the front and the small cogs on the rear, you will get rub against the front derailier, however this what i am referring to is rub on the inside of the large chain ring, when on the middle chainring and the 3 smallest cogs on the rear, the chainline is pretty much dead straight, this should happen....

    A mate of mine came down the other night, he has an Obea (something like that - Spanish) and he has Shimano Sora all the way through, his is also a tripple, i put his bike in my workshop stand and went through every gear, he only got slight chain rub on the front derailier when in the smallest chain ring on the front and the 2-3 smallest cogs on the rear, which you can understand due to the chain angle, however no other derailier rub or inner chain ring rub was evident at all.....
  • SoniSoni Posts: 1,217
    Mister W wrote:
    You're right, that shouldn't happen.

    I'm struggling to think why the rubbing is that extreme on a triple. You might get a little bit when you're on the smallest cog if you've got a small frame but the other cogs should be okay. As a long shot...... are you running a 9 speed chain on a 10 speed chainset? I think (and I'm happy to be corrected) a 9 speed chain is slightly wider so that might be causing the rubbing.

    If it's not that, try putting it in the offending cogs and looking along the chain line to see how straight it is. Something may be out of alignment.

    Its a nine speed groupset with a 9speed SRAM chain on it....
  • As I said before, I would check the BB axel length. I would put money on it being too short for your triple.
    I have only two things to say to that; Bo***cks
  • SoniSoni Posts: 1,217
    As I said before, I would check the BB axel length. I would put money on it being too short for your triple.

    I phoned my bike shop up this afternoon and explained its still playing up and i mentioned what you said about the axel length, i'm taking it down saturday morning for when they open and they are going to check it.
  • nmcgannnmcgann Posts: 1,780
    Triple setups are pretty tricky.To get the maximum gear range on every chainring without rubbing takes just the right length bottom bracket, a frame with chainstays not too short and a very good set up of front mech cage position and angle.

    On a 9-gear setup I'd be happy to get 1-7 on the little ring (where 1 is the biggest cog in the cassette), 1-8 on the middle ring and 3-9 on the big ring. Note that I count on getting the biggest cog from the middle ring - I use my triple like a double most of the time (as I think most people do) so need to get the lowest gear on the middle ring.

    Neil
    --
    "Because the cycling is pain. The cycling is soul crushing pain."
  • AxAx Posts: 36
    I have the same problem on my bike - It's a 105 compact and when in the small ring at the front the chain rubs on the inside of the big ring if it's in either of the smallest 2 cogs at the back. Solution? Avoid those 2 gears!
    2005 Dawes Galaxy
    2008 Specialized Rockhopper Disc
    2009 Focus Variado Expert
  • SoniSoni Posts: 1,217
    nmcgann wrote:
    Triple setups are pretty tricky.To get the maximum gear range on every chainring without rubbing takes just the right length bottom bracket, a frame with chainstays not too short and a very good set up of front mech cage position and angle.

    On a 9-gear setup I'd be happy to get 1-7 on the little ring (where 1 is the biggest cog in the cassette), 1-8 on the middle ring and 3-9 on the big ring. Note that I count on getting the biggest cog from the middle ring - I use my triple like a double most of the time (as I think most people do) so need to get the lowest gear on the middle ring.

    Neil

    I'd be happy to get that, however i'm presently getting about 1-6 on the small before it starts rubbing the front mech, 1-6 on the middle before it starts rubbing the inside of the front large chain ring, and about 4-9 on the large.....

    However, the guy i rode with the other evening had an Obea (something like that Spanish make) and he had Sora all the way through his setup and it was also a Tripple, he was getting EVERY single gear without ANY rubbing on either the front mech of the chainrings apart from about 7-9 on the small chainring when it started rubbing (very very slightly may i add the front mech)...which i would be very happy with.
  • nmcgannnmcgann Posts: 1,780
    Soni wrote:
    I'd be happy to get that, however i'm presently getting about 1-6 on the small before it starts rubbing the front mech, 1-6 on the middle before it starts rubbing the inside of the front large chain ring, and about 4-9 on the large.....
    ....

    The middle ring range does suggest bottom bracket length is too short, but I don't know how sortable that is if you have an external bearing BB like most of them are now.

    Very easy to fix with good old fashioned square-taper BBs.... :wink:

    Neil
    --
    "Because the cycling is pain. The cycling is soul crushing pain."
  • SoniSoni Posts: 1,217
    nmcgann wrote:
    Soni wrote:
    I'd be happy to get that, however i'm presently getting about 1-6 on the small before it starts rubbing the front mech, 1-6 on the middle before it starts rubbing the inside of the front large chain ring, and about 4-9 on the large.....
    ....

    The middle ring range does suggest bottom bracket length is too short, but I don't know how sortable that is if you have an external bearing BB like most of them are now.

    Very easy to fix with good old fashioned square-taper BBs.... :wink:

    Neil

    On my way down to the bike shop now, they are going to have a look at it for me, will post up the outcome when i get back.
  • redddraggonredddraggon Posts: 10,862
    You need to trim the front mech
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  • SoniSoni Posts: 1,217
    You need to trim the front mech

    Its not rubbing on the mech, its rubbing on the inside of the largest chainring...
  • SoniSoni Posts: 1,217
    Just got back from Bikeshop, the guy they've got there should be a mechanic for one of the tour teams, he's really great.

    Besides the problem with the chain rubbing on the inside of the largest chainring, it was also suffering from shifting problems up and down on the rear cassette.

    I had the outer and inner gear cables replaced around the rear mech about a year ago.

    The guy today initially attempted to adjust the gears, this didn't work, he said they are all over the place, so he stripped the inner cables out, replaced, then removed the outer cable near the rear mech, measured it, i asked why he's measureing it, he said he finds best results when the outer cable is trimmed at 14", and this one is only 12", so he replaced the outer cable, did some more tweaking, and some more limit adjusting, and bingo, every gear on the rear perfect first time every time.

    Then came the front chainring, he removed the bottom bracket, and replaced it with a new bottom bracket which was 2-3mm longer on the axel, asked me to take it for a spin.

    I couldn't believe the difference, the only way i can explain it is each gear change is 'punchy'. It seems to snap/punch into position really sharply on the rear, and the rubbing has dissapeared completely on the front largest chain ring, the only drawback is there is a 'very slight' longer shift required to get the chain over from the middle chain ring to the largest chain ring, but when i say slightly longer, its not difficult to do, and it doesn't ham or anything like that, its a really quick change still but you can tell that the chain is travelling just that little bit further than it was.....but i can live with that, as every gear is working brilliantly, and also NO rubbing on any gear, on either chainrings or front mech, the only rubbing i have now is in gears 1 and 2 when on the largest chainring on the front, which due to the chain angle this is quite acceptable and you would never be riding in those gears anyway!

    So - i'm really happy again! :D
  • In that you needed a longer BB that means that your chain-line was out, which would explain the rubbing and your problem with the gears. Good that it's fixed though.
  • SoniSoni Posts: 1,217
    In that you needed a longer BB that means that your chain-line was out, which would explain the rubbing and your problem with the gears. Good that it's fixed though.

    I'm just wondering how many Trek 1.5 tripples have been sold and whether they've all had this problem.......
  • redddraggonredddraggon Posts: 10,862
    Soni wrote:
    You need to trim the front mech

    Its not rubbing on the mech, its rubbing on the inside of the largest chainring...

    I get that too and my BB and axel is the right length.

    (However wierdly when in the 30t ring and smallest sprocket there is rubbing, but there is when I'm in the 39T and the smallest sprocket)
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  • SoniSoni Posts: 1,217
    How are you gauging the shaft/axel of the bottom bracket being the correct length? Not doubting your competence at all, just wondering, as the mechanic today looked at the chainline together with the shop owner, one was looking at it from back to front, and the other was looking at it from front to back, and they both thought it looked in line, however they thought they would try one slightly longer and it paid off....

    I can't believe that bottom brackets are available in such small increments as 2-3mm, you would have thought they would have been at least an inch increments...

    I don't think there is anything more frustrating than a noisy drive chain, the bike was sounding like a cement mixer in some gears but is now super quite, smooth, and just feels a pleasure to ride.
  • redddraggonredddraggon Posts: 10,862
    I've got external bearings and the axel is permanently connected to the driveside crankarm/spider :wink:

    My problem is more likely related to short chain stays.
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  • k-dogk-dog Posts: 1,652
    Soni wrote:
    I can't believe that bottom brackets are available in such small increments as 2-3mm, you would have thought they would have been at least an inch increments...

    You can get lots of different types - for different types of chainset and doubles or triples - http://www.chainreactioncycles.com/Mode ... elID=17473

    The most common mistake is using the double length for a triple - that puts the chainset about 6-9mm too far inboard so could make the chain rub on the outer chainring - wouldn't affect using lower gears on the cassette though.
    I'm left handed, if that matters.
  • k-dogk-dog Posts: 1,652
    The way I check if it is the right length is to use Sheldon's chart - http://sheldonbrown.com/bbsize.html

    I don't think you could eyeball it and tell if the spindle was only a few mm too long - even a 9mm difference is only a 4.5mm of the chainrings.
    I'm left handed, if that matters.
  • SoniSoni Posts: 1,217
    k-dog wrote:
    Soni wrote:
    I can't believe that bottom brackets are available in such small increments as 2-3mm, you would have thought they would have been at least an inch increments...

    The most common mistake is using the double length for a triple - that puts the chainset about 6-9mm too far inboard so could make the chain rub on the outer chainring - wouldn't affect using lower gears on the cassette though.

    That sounds EXACTLY what happened in my case, as this new 2-3mm one has stopped the rubbing on the inside of the large chainring...
  • I now don't get any chain rub when on my outer 12 sprocket and double compact chainset - the solution to it from a few months ago was to slightly move the chainrings away from each other.
    Graham
  • bing gordonbing gordon Posts: 662
    edited November 2009
    wow ! , im glad i read this thread as im at my wit's end with a bike i recently purchased 2nd hand.
    i recently bought a specialized roubaix pro 08 and its the 1st proper bike i've ever owned and it suffers from chain rub on the inside of the large chain ring.
    the bike has a compact 50/34 (not the racing pro chainset) but no matter how much adjustment to the front/rear mech that when im on the smaller ring the chain rubs/catches the inside of the large ring.

    it doesnt just rub but when im on smallest ring its sometimes that bad it snags onto the inside of the large ring and lifts up off the small ring and skips a beat so to speak.

    the bike it virtually unrideable as it rubs and catches onto the larger ring all the time.
    when i looked at the distance between the large ring and the frame the large ring seems awful close to the bike but i wouldnt know what distance its meant ot be anyway.
    and when i read the specs on the bike
    http://www.specialized.com/us/en/bc/SBC ... spid=33602

    BOTTOM BRACKET - Specialized, oversized integrated
    CRANKSET - Specialized FACT carbon crankset, integrated oversize design
    CHAINRINGS - 50x34T
    what does "oversized" mean ?.
    now after reading this thread it got me thinking , is the bottom btacket too small ? the bike originally would have a racing chainset not a compact.
    i did add mavic krysium wheels as soon as i got the bike the wierd thing is , i didnt think i would need a mavic spacer for the rear cassette with it been a 10spd cassette but the cassette cogs were loose without it.
    when i added the spacer the cassette ran flush to the top of the hub and tightened up fine.
    im lost now as its all getting a bit too too techy for me ,would anyone have any advise as im not riding at the mo and im awful short on money after spending a fortune on the bike.

    i thought of trying some very thing 1mm -1.5mm chainring spacers to put over the ring nuts so there's a bit more clearance for the chain , would this work ?.
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