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Date: 06 Nov 2006 13:12:07
From: brink
Subject: So is this crank toast or what?
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OK, a year ago I bought a new Trek Navigator 100 hybrid bike... actually
one for me, and a matching female version for my wife... yeah, I bought a
couple of cheapy bikes... so sue me... ;-) In all honesty, I wanted a
bike I could beat up a bit and also not be paranoid about being stolen when
I locked it up in public places...
I've actually been quite happy with it... biked in 20 different states,
lots of highways, roads, MUPs, the beach, the mountains, desert, trails,
dirt, rocks, whatever... replaced a few things like the rear gears and the
pedals, and course a few tires and tubes...
The latest problem is a bit trickier though... the chain keeps falling off
the front gear when I'm on the highest ring -- the outside ring of course...
the pants guard came off several months back and I think that it might have
been preventing this from happening in the past...
It tends to come off when I really push it -- standing up in teh pedals for
instance -- the high torque just seems to pull it right off the gear. Not
good of course, especially when in traffic...
My LBS looked at it and they can't figure out why it's doing it... except
to tell me "yeah, this is the bottom-of-the-line parts, they aren't very
good..." Yeah, thanks for telling me that you sell junk. They tried some
adjustment that seems to have had zero effect. The only other thing they
can imagine doing is replaceing the entire crank since the gears are
apparently attached directly onto the crank itself... all of it needs to be
replaced if they want to replace the gears they say...
Thoughts? Any help is appreciated.
brink
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Date: 06 Nov 2006 19:21:55
From: David L. Johnson
Subject: Re: So is this crank toast or what?
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On Mon, 06 Nov 2006 13:12:07 -0800, brink wrote:
> The latest problem is a bit trickier though... the chain keeps falling off
> the front gear when I'm on the highest ring -- the outside ring of course...
> the pants guard came off several months back and I think that it might have
> been preventing this from happening in the past...
>
> It tends to come off when I really push it -- standing up in teh pedals for
> instance -- the high torque just seems to pull it right off the gear. Not
> good of course, especially when in traffic...
>
> My LBS looked at it and they can't figure out why it's doing it...
Huh? Your problem is either an adjustment problem, or a wear problem.
Let's check out a few things:
Is the chain new? Did the problem appear when the chain was replaced? If
so, probably the chainring(s) is/are worn. Replace them, and it should be
OK.
If the chain is not new, then probably the derailleur is out of
adjustment. Adjust it.
If this shop checked on both of these, I'd be surprised.
Why did the pants guard come off? Those tend to be attached on either the
chainring bolts, or maybe welded. There may be an answer in that.
> except to tell me "yeah, this is the bottom-of-the-line parts, they
> aren't very good..." Yeah, thanks for telling me that you sell junk.
Well, not only are they fessing up to that, they want you to buy another
one.
Look, even cheap bikes these days are pretty good. Don't apologize for
staying within your budget. It should work reliably for many miles before
something bad happens. You do need to check these things out, though.
> They tried some adjustment that seems to have had zero effect. The
only
> other thing they can imagine doing is replaceing the entire crank since
> the gears are apparently attached directly onto the crank itself... all
> of it needs to be replaced if they want to replace the gears they say...
Well, there are many cranks that are set up that way, none of them being
very expensive. You could spend a little more and get replaceable
chainrings, but that is up to you.
--
David L. Johnson
__o
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Date: 06 Nov 2006 15:43:21
From: Downhill-Rider
Subject: Re: So is this crank toast or what?
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I hope this isn't too late but I work in a shop in Toronto Canada and
your local LBS is full of crap. Do a self test on your bike...first
flip it over and slowly spin your crank to see if your actual
chainrings (3 sprocket things in the front) are bent. You said that
your pant guard fell off the only reason this should have happened was
if you hit your chainrings off something and in doing so you might have
bent it and therefore under high torque on that specific location the
chain doesn't sink all the way down to the bottom of the chainring
tooth and therefore it skips.
The second test you need to do is to look straight down your front
derailleur and make sure it's two outer cages are parallel to your
chainrings. If not this is a problem. Things do loosen with time and it
should only mean straighting it to fix the problem. If you here a
rubbing while riding then this is definetly a problem.
The third test is to make sure your cranks ain't rounded and the
easiest way to do this is to first make sure your cranks ain't loose
and if they ain't flip the bike upside down again stand over it and
using your hands pedal it slowly while placing all your weight on the
cranks. If the cranks are stripped you will feel a sudden shift as you
follow through with a complete revolution. (If this is the case u need
new cranks or you can get just that crank arm replaced). This will also
only be a problem if the crank that's stripped is the drive-side crank.
If it's problem #2 and it keeps happening just keep giving your local
LBS a hard time till they figure it out...it's a little time consuming
if it's completly off and some derailleurs are really finiky and
therefore it takes alot of effort to find the magical spot.
Give them a hard time. If you feel your getting ripped off go to a
second shop for a second opinion.
Best of Luck.
Peace
-GO BIG OR GO HOME!-
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