Bicycle Mechanics - Threads on crank shredded, is there a solution?? PLEASE HELP !!
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05-02-06, 04:08 AM
I bought an old bike, basically for the frame (Reynolds 453). And after completing at least a months restoration, the bike was put back together, whilst riding the crank bracket came loose and I tried to put it back on without success. I took it to the local bike shop and was informed that the bolts were put on incorrectly, i.e left hand thread put on right hand so and vice-versa. He said that the threads might be knackered on the frame now, and if that is the case then the frame is scrap............:mad:
Now you can imagine after putting in all that effort, I'm not best pleased, more so, as the crank was put back together by someone else (trying to help).
My question is this : If the threads are done, is there a way of securing the crank, but NOT screwing into the frame ?
The frame was probably made in the 70's, and is on an old Falcon Team Equipe bike.
Your help would be appreciated.
05-02-06, 04:45 AM
I think this is what you need
05-02-06, 05:32 AM
Wow, what an interesting BB! Hope I will never need to go there. But I am also amazed that someone managed to thread anything onto anything else that is reverse threaded. It must have taken some serious effort. Any chance that the shop were mistaken and it was actually an italian dutch or some other set up where the threading causes the BB sheels to unscrew? Just being hopefull.....
...i.e left hand thread put on right hand so and vice-versa. ...
I don't think it's possible to to install left hand threads onto right hand threads.
The threads could be messed-up for other reasons. Can you "chase" or re-cut the threads in the shell?
05-02-06, 12:22 PM
While working at a bike shop, a friend of mine installed pedals on the wrong sides. When he got to the second one, it wouldn't thread in all the way, and asked for my help. I could not belive what he had done, it was a rental bike so we threaded the stuck one in all the way and did a few bunny hops and they still held. So it is quite possible to thread a right hand thread into a left had and vice versa.
Oh and by the way we didn't rent the bike we ordered new cranks.
05-02-06, 08:31 PM
I think this is what you need
IF you use this BB, you will need an LBS or machine shop to face the BB shell so the taper will center in the shell.
05-03-06, 11:45 PM
Is it possible to use a helicoil on them?
05-03-06, 11:58 PM
wait, what is going on now? Maybe it's late, but I have no idea what is stipped.
The thread title says cranks are stripped, later you say the "crank bracket" worked itself out which I assume is the bottom bracket, but that uses cups not bolts to secure itself into the threads of the frame.
Asssuming again that it's your BB threads that got buggered, we need more info about your frame.
If it has an english threaded bottom bracket, then the threads CAN be re-threaded, but they will be rethreaded to italian sizing/handedness, and you will have to use an Italian sized bottom bracket.
If it was already an italian cupped frame, then the specialty BB linked to above is a viable option.
If it was a French frame that is screwed up, then you may be SOL>
05-04-06, 01:04 AM
Both cups of a French bottom bracket are right-hand thread. You would have to put both of them in backwards to arrive at this point.
Now Swiss on the other hand.....
My guess is that a cartridge bottom bracket was installed, because the lockring would be on the drive side if it was a cup and cone bottom bracket.
05-07-06, 09:03 PM
Hi all, thanks for your replies........were a bit further down the line.
The original bike shop who looked at it, just removed the lock ring and the other bolt and tried to tighten them up around the bottom bracket. So I picked up the bike and went on my way, on my ride home, sfter 2 miles, the bolt shelled out again......:mad:
Called him up and called him every name under the sun, went back to work and picked up my MTB and rode that home, but on the way I came across a small, well lived in bike shop. As the door was open I popped my head in and asked the question, he immediately informed me that a Threadless BB would be the only saviour for this frame. So the next day, he set about fixing this T-BB to the bike, and I gotta say, I'm more than happy with it.
Bike is up and running now, and I'm commuting into work now. Hope I can keep it up.
I'll post some pics of the bike now.......it's not much, but I put a lot of effort into it, and am really happy with the results.
Anyone have any information on the Reynolds 453 frame, I cant seem to find any info on the net.
05-07-06, 11:02 PM
The original bike shop who looked at it, just removed the lock ring and the other bolt and tried to tighten them up around the bottom bracket. So I picked up the bike and went on my way, on my ride home, sfter 2 miles, the bolt shelled out again......:mad: This is still confusing... the only bolts down there holds the crankarm onto the bottom-bracket spindle. The thing that goes into the bottom-bracket shell on the frame are cups. Which part is giving you trouble? If the crankarm bolts are backing out, you may need new crankarms as well.
05-08-06, 01:23 AM
Sorry not up to date on all the terms, but sounds like its the cups that were the problem, and the thread that they go into the frame was knackered.
The threadless BB is holding now, and I am happily using the bike.
I'm sure if I carry on cycling as I am, I will invest in a new bike. But have learned a lot during the rebuild anyway.
Thanks again all.
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