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Old 04-24-11, 04:23 AM   #1
jet16lg
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Crank replacement question-bolt removal?

I'm a amature bike mechanic-basically, I''m fairly new to biking and I have a 80's Centruion LaMans that I ride. I've been using this bike as my learning pad for repairs as things break or I decide that I want to upgrade them. Most things have been pretty easy so far (rear derailure, handlebars, Etc).

The current crank set is a biopace double with a fairly high tooth count so I've bought a new compact crank to try out, it's square taper also. I did some reading on crank removal and things went pretty well. I took off the dust caps, there was a Nut that I removed, then I used my crank removal tool to get the crank arms off. All that went pretty easily.

Then I put on my new crank arms however I then noticed that the new crank arms had self extracting bolts to install. The bottom bracket still has the bolts attached from the previous crank removal making it impossible to use the new self extracting bolts.

So, did I do the crank removal properly? Where the bolts that were on there previously supposed to come off during my crank removal?

If they were not supposed to come off, is there a easy way to get them off so I can use the self extracting bolts that came with my new crank?

Just to see how the cranks would look, I put the new cranks on and used the old nut to secure them in place. The cranks seem nicely secured and ridable. However, it does not look "nice" with the exposed nut/treads. I could find some dust caps and leave it as is but I just wanted to check with more experiencd mechanics to see if I was doing things correctly.

Thank you for your time and help!
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Old 04-24-11, 04:48 AM   #2
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You have a nutted bottom bracket there so the only choice is to use the nuts that came with. Make sure you get 'em tight.

You'd need a different bottom bracket if you want to attach cranks with bolts.

Nutted BBs are typically considered inferior, but I rode on them for several years without much trouble.
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Old 04-24-11, 06:43 AM   #3
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Sorry to steal the thread, but I'd thought I'd ask in here rather than start a new thread as it is sort of related?

Anywho, I also just replaced my crankset on my bottom bracket which is of the square-taper, nutted variety. The drive side went on normally, however the non-drive crank didn't seem to go on too far, maybe a thread or two shy of fully engaging all of the threads on the crank-nut. It is cranked on there reasonably tight (but not overly), so should I be worried about this or should it be fine?

It is an old 80's fuji with an uneven spindle length and a new, generic/no name japanese crankset.

(however with the nondrive side a bit further out, it actually creates a nice symmetry between the cranks, whereas they were lopsided previously [drive side sticking out further])
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Old 04-24-11, 10:50 AM   #4
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I would remove the self extracting bolts ring, It takes a tiny pin spanner to unscrew.
May be a tool to buy , or turn the job over to someone who does have one..
Then you can test fit the crank on your BB spindle.
I expect the design of the crank is such that you need a different length of a BB.

but that is not something that can be prescribed over text based .. this place.
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Old 04-24-11, 02:02 PM   #5
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Originally Posted by hoyc View Post
Sorry to steal the thread, but I'd thought I'd ask in here rather than start a new thread as it is sort of related?

Anywho, I also just replaced my crankset on my bottom bracket which is of the square-taper, nutted variety. The drive side went on normally, however the non-drive crank didn't seem to go on too far, maybe a thread or two shy of fully engaging all of the threads on the crank-nut. It is cranked on there reasonably tight (but not overly), so should I be worried about this or should it be fine?

It is an old 80's fuji with an uneven spindle length and a new, generic/no name japanese crankset.

(however with the nondrive side a bit further out, it actually creates a nice symmetry between the cranks, whereas they were lopsided previously [drive side sticking out further])
It might be worth pulling both crank arms, rotating the spindle 1/4 or 1/2 turn, and then reinstall the arms. There may be something about the current orientation of the arm-spindle interface preventing it from seating properly which could be resolved by doing this. It will also give you another chance to fully inspect the parts before reinstalling. You will want to mark the spindle before removing the arms, though, so you have a reference.
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Old 04-24-11, 04:31 PM   #6
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I told my dad about it and he also made a good point of saying that it is possible they could be a mismatched set, thus may have a different sized hole? These were afterall a generic set that the local bike co-op ordered for me from their part supplier.

Maybe I will try and remove just the non drive, and rotate 90'deg? And if that helps any, do the same with the drive-side.
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Old 04-24-11, 05:28 PM   #7
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Maybe I will try and remove just the non drive, and rotate 90'deg?
Are you sure about rotating just the NDS?
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Old 04-25-11, 12:55 AM   #8
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Thank you Lester for the response. That makes sense that the bottom bracket is setup this way-it being a nutted bottom bracket. I might end up buying a new bottom bracket since the cranks i bought were ISO and the bottom bracker is JIS. From what I've read on Sheldon Brown, you can sorta interchange them. So, I just wated to do a few rides and see if I liked the compact crank. If so, I'll buy the proper bottom bracket to install.

Thank you again for you help!
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