Problem with my mountain bike...can anyone lend some advice?
05-19-07, 03:00 AM
#1
Newbie
Thread Starter
Join Date: May 2007
Posts: 3
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Problem with my mountain bike...can anyone lend some advice?
Hi,
I am a fairly green mountain biker, I am primarily a BMXer in my early days and progressed to a basic GT mountain bike to keep myself in shape now I'm older.
I have a small problem with my GT mountain bike - when I cycle OUT of the saddle e.g.up hills or for speed on flats.....the pedal slams violently from 12 o'clock position to 6 o'clock position occasionally. I had this same problem on a hire-bike also once.
I am unsure wether it is a crank or rear sprocket etc.
I went to my 2 mountain bike shops to ask (without the bike) - one of them said 'ooooo, that could be the crank, you might need a new crank'. The other said it could be rear sprocket - but both gave that impression that they would rack up lots of hours of labour....I am concerned I'm going to be ripped off here as the fault is intermittent and not obvious unless you went for a 15-20 minute bike run pedalling out of the saddle.
Can anyone lend some advice?
I am a fairly green mountain biker, I am primarily a BMXer in my early days and progressed to a basic GT mountain bike to keep myself in shape now I'm older.
I have a small problem with my GT mountain bike - when I cycle OUT of the saddle e.g.up hills or for speed on flats.....the pedal slams violently from 12 o'clock position to 6 o'clock position occasionally. I had this same problem on a hire-bike also once.
I am unsure wether it is a crank or rear sprocket etc.
I went to my 2 mountain bike shops to ask (without the bike) - one of them said 'ooooo, that could be the crank, you might need a new crank'. The other said it could be rear sprocket - but both gave that impression that they would rack up lots of hours of labour....I am concerned I'm going to be ripped off here as the fault is intermittent and not obvious unless you went for a 15-20 minute bike run pedalling out of the saddle.
Can anyone lend some advice?
05-19-07, 03:57 AM
#2
Non Tribuo Anus Rodentum and off to the next adventure (RIP)
Join Date: Dec 2002
Posts: 9,161
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 2 Times
in
2 Posts
I'd put my money on the rear sprockets & chain. Maybe an hour job if the wrench dogs it. Parts can be reasonable to pricey depending on what you get.
__________________
05-19-07, 04:56 AM
#3
Senior Member
Join Date: Apr 2007
Posts: 175
Bikes: 90' Trek 1000, Trek 700 cyclocross conversion, Legnano, 54 Indian Scout, 1980 Trek 412, Zeus Professional?, Raleigh Team USA, Raleigh Technium, Scott Spark 60,...
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Likes: 0
Liked 2 Times
in
2 Posts
Possibly the chain is temporarily slipping partly off the front or rear sprocket, just for a single stroke? Or something in the freewheel is broken? I don't think it would be hard to fix.
I would start off by re-adjusting the indexed shifting (it might be very slightly off). If that doesn't fix it, maybe swap out the freewheel...
I would start off by re-adjusting the indexed shifting (it might be very slightly off). If that doesn't fix it, maybe swap out the freewheel...
05-19-07, 05:48 AM
#4
Senior Member
Join Date: Feb 2004
Location: St Peters, Missouri
Posts: 30,225
Bikes: Catrike 559 I own some others but they don't get ridden very much.
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 1572 Post(s)
Liked 643 Times
in
364 Posts
Originally Posted by Stacey
I'd put my money on the rear sprockets & chain.
90% rear derailleur adjustment. Maybe a little higher.
9% worn chain and/or cassette.
<1% crank. Maybe a little lower.
05-19-07, 08:22 AM
#5
Newbie
Thread Starter
Join Date: May 2007
Posts: 3
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Thank you very much everyone for fast replies.
I am relieved to hear my crank is OK probably!
It should be noted the bike has maybe 60-70 miles in total on it, not a great deal. So I am wondering if the derail-adjustment would be more likely as a worn sprocket or chain would warrant more miles?
How would I adjust the derail thing?
I am relieved to hear my crank is OK probably!
It should be noted the bike has maybe 60-70 miles in total on it, not a great deal. So I am wondering if the derail-adjustment would be more likely as a worn sprocket or chain would warrant more miles?
How would I adjust the derail thing?
05-19-07, 09:24 AM
#7
Non Tribuo Anus Rodentum and off to the next adventure (RIP)
Join Date: Dec 2002
Posts: 9,161
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 2 Times
in
2 Posts
www.parktools.com ~ All you need to know and then some. 
__________________
05-19-07, 10:05 AM
#8
Senior Member
Join Date: Feb 2004
Location: St Peters, Missouri
Posts: 30,225
Bikes: Catrike 559 I own some others but they don't get ridden very much.
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 1572 Post(s)
Liked 643 Times
in
364 Posts
Originally Posted by yoshi123
It should be noted the bike has maybe 60-70 miles in total on it,
Rear derailleur adjustment is now at 99+%.
