Sticky bottom bracket/cranks or...??

Discussion in 'Road Cycling' started by old911guy, May 16, 2010.

  1. old911guy

    old911guy New Member

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    I started training on the velodrome recently with, obviously, a fixed gear track bike. After a couple of days in a row, I got on my road bike to do a training ride over some local mountains. While spinning downhill after just starting out, I noticed what felt like a stickiness in the pedal stroke. Like I was getting mechanical resistance from inside the bottom bracket. I pulled over and tested it on the side of the road but didn't nontice anything. I'm wondering if this is due to the transition from fixed gear to freewheel again? Or if there is something really wrong with my bike. Next step is to take it in to be looked at. It only seemed noticeable when spinning at a high RPM.
     
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  2. tafi

    tafi Member

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    Track bikes have a habit of making legs lazy through the deader parts of the pedaling action. Momentum can carry your legs through the dead spot on a track bike whilst the freewheel on the roadie prevents this from happening. You don't say what part of the cycle this feeling occurs in but that would be my first guess.

    I can't see how a mechanical issue could be causing problems only at high rpm. If it were bearings you should also be able to feel it when crankng slowly and by hand.
     
  3. serra

    serra New Member

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    I agree with tafi. At rmps beyond what I can pedal smoothly, even being used to a freewheel, the pedal stroke feels "dead" at the bottom. If you can't find anything wrong with it, and it works, I can't think of anything else it could be.
     
  4. old911guy

    old911guy New Member

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    Thanks for a thoughtful response to what I'm sure looks like a nutty question. The reason I notice it at high RPM is because there is no "expected" load for me to feel, so I notice what feels like a weird "stickiness". I've been trying to get comfortable with spinning at 90+ RPM, which isn't natural for me. I tend to be more of a Jan Ulrich than a Lance Armstrong... ( I wish, ha ha....but I think you get the idea )Funny thing is that I thought that riding the fixie would encourage better pedaling technique that would transfer to a more efficient stroke on the road. This bottom bracket is near the end of its life, so I will have it taken apart to look at the bearings and possibly replace it. If that doesn't "fix" it, then I know it's that my pedal technique really is that bad!

     
  5. serra

    serra New Member

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    Haha, sounds like a good plan :)
    I'm trying to get my rpm up a bit too, after ~80 I start to feel my form going. I wish it would stop raining so I could ride, I just overhauled both wheels and my bracket, it's too soon to risk them getting gunked up again!
     
  6. tafi

    tafi Member

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    It's a common misconception that a track bike or fixie would improve one's pedalling "efficiency" (whatever that is). Track racing can be good at improving your strength (you need it to get a big gear moving) and can force you to pedal at high cadence (you need it to keep up - no gear changing allowed).

    This doesn't translate into the ability to pedal "full circles" becasue your legs are carried through the dead spot by your own momentum. In this respect the legs actually get lazier.

    I would exercise caution and not bother spending money taking the BB apart unless it really is seizing up (you'll surely know when it does - you won't be able to spin it at all). Rather take a bit of time on rollers or trainer (if you have them) and see if the problem gradually abates as you get used to the roadie again.

    Whether you spin or grind makes no difference to your power output. Spinning can be beneficial as it allows one to respond faster to changes in pace or gradient. This is probably a good thing over long race distances.
     
  7. old911guy

    old911guy New Member

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    Thanks for such a thoughtful response. I started to suspect this on the road ride today, that I had gotten used to the pedal kicking up based on the track bike's momentum and that "maybe" the trailing leg had gotten lazy. But I didn't want to believe that. If it me "lifting" a dead/lazy trailing leg, it sure isn't what I would have expected it to feel like. On the RPM thing, my coach is big on high RPM's in that I should not be using my fast twitch muscles all of the time, but only when I need them, otherwise I will crack at the wrong time. I'm training on the track with 78 gear inches, which feels feathery light. I want more inches because I can push them! I spin around doing 200 meter drills and feel like I'm spinning crazy RPM's, but in reality I'm not. It's a process and I'm learning a lot.

     
  8. alfeng

    alfeng Well-Known Member

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    Just out of curiosity, is that an ISIS bottom bracket ... or, something else?
     
  9. old911guy

    old911guy New Member

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    Is a Shimano Ultegra BB considered an ISIS BB?

     
  10. swampy1970

    swampy1970 Well-Known Member

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    Take the chain off the chainrings and turn the cranks. Do you feel any resistance? If you spin them do they turn for quite a few revolutions? If so they there no restriction. While you're at it grab the crank and test for BB play by trying to move the cranks in and out (towards and away from the bottom bracket) if that is fine too then you have no worries whatsoever with the bottom bracket.

    It's a simple test that takes less than a minute...
     
  11. alfeng

    alfeng Well-Known Member

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    No, the Shimano 6500-or-6503 BB is an OCTALINK.
     
  12. alfeng

    alfeng Well-Known Member

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    This is a very good suggestion ... but, it should be noted that the BB bearings may respond differently when under load, so the test may not be conclusive.
     
  13. old911guy

    old911guy New Member

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    A late reply, but I wanted to update you guys on the solution. I had the bike examined closely at my LBS. It turns out that the chain had a pretty big kink in one of the links, and it was worn out. I changed that out, but it wasn't the problem. It really was from riding the fixie on the velodrome. My trailing leg got lazy. I can't believe that I couldn't tell that this had happened, and that I was doing this. It certainly didn't feel like it was coming from my own trailing leg. It felt so....mechanical. Very very weird. It just goes to show how quickly (a few track sessions) can cause a change in pedal technique.
     
  14. swampy1970

    swampy1970 Well-Known Member

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    More tests straight from NASA:

    Take the chain off and press down hard on both pedals... Do you feel a 'clunk'.

    Seriously though - how long does a thread need to get over a bottom bracket? Just tell the poster to take some "joint juice" and go out and do some training :p
     
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