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Short answer: no. If you're lucky the axle is simply installed the wrong way round so rather than swapping the cups, swap the axle round and see if that fixes the problem. The two cups have opposite threads, one left hand thread and one right hand thread. If you swap them and force them in you will cross thread the frame, and that's ugly to fix. ...


2

Based on your photos, take the other crank arm off, pull the whole bottom axle unit out attached to the welded side. and fit a new cartridge bottom bracket. Cost is not small but its not huge either - certainly cheaper than cranks. Cup and cone bottom brackets are old tech, and cartridges are far superior. If you're lucky, you can now work on unmounting ...


3

This frame either uses a BB386 Evo "standard" or a Pressfit 30 "standard". You can determine which by measuring the width of the frame at the BB shell. If 86.5mm it is BB386Evo. If 68mm it is Pressfit 30. If it is a Pressfit 30(68mm shell) this BB is a direct fit for the Shimano crank without extra spacers. this is the PF30 version of the BB30 bottom ...


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The core problem is that you need the thread on the bottom bracket axle to attach the new crank, and that will have probably been damaged by your welding. If you can get the bolt out after unwelding, it might be possible to keep the current BB. If your BB is this style, you might be able to cut the crank off, leaving enough of the bolt to weld on a small ...


1

From what I can see the various "MegaExo" BB labels refer to the spindle size and crank fixing, rather than the size of the shell in your frame. There will be subtleties with frame clearance, but that's something for Giant rather than the BB or crankset people. From that website I got this screenshot: You will need a HollowTech II BB, or some that's ...


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You can determine the bottom bracket size by measuring the width of the bottom of the shell.


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I found this diagram online which I hope will allow me to determine the size of the bottom bracket by measuring the width of the shell. I found out that the bike is an old Centurion. I was not able to find any series number engraved on it anywhere so I haven't been able to determine the exact model or how old it is but just in case anyone wants to ...


2

A loose crank arm can damage both the bottom bracket and the crank arms. In your case, since you've run the crank arm til it fell off the bike, it is likely you ruined the bottom bracket. If your crank arm is loose, immediately stop and tighten it. You will need to likely get a new bottom bracket and possibly yet another new crank arm. Replacing a bottom ...


3

Based on that its probably a cup-and-cone bottom axle in English threadding 68mm. That's a very common size. However the fact this loverly old road bike has a single-speed conversion and bullhorn hack/chopped handlebars, it could be a double or a triple bottom axle that has packers, or it could have been replaced with the correct length for the ...


1

The only measurement for a bottom bracket you can do with the bottom bracket still on the bike is to do the shell width, which is the width of the frame where the bottom bracket installs. In order to measure the spindle length, you need to remove the cranks and then measure the spindle length. There is no guarantee that the spindle is symmetric or the width ...



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