Bike Crank Removal

Serraph

Serraph

Serraph

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Joined
6 Jan 2009
Posts
216
Location
Norwich - UK
OK, so I was thinking about replacing my old 11 year crank on my bike, and have seen a few videos on how to do this, however they all seem to be for newer bikes. How would I do this for my older bike? Here are a few pics.






Is it just a case of undoing and removing the bolt on you can see on the second image? Or is there another way to do it? If it helps it is an old Apollo Radiant from Halfords.

Thanks.
 
Yep, it's like the BMX one-piece cranks. Take the pedals off, and undo the bottom bracket cups that you pictured and it should wriggle out. The only issue I can foresee is if your bottom bracket isn't threaded inside. You won't be able to replace with a standard cartridge type bottom bracket bearing. I'm not sure what's compatible with that setup.
 
Ah right, a one-piece, so that would be like THIS then? Any idea what size wrench I would need? As the adjustable one I have is not big enough.

So I would need new bottom bracket if I were to replace it with a newer crank? Because I was thinking of replacing it with this, nice and cheap, but says for use with square taper bottom brackets, so I would also need to get something like this?

Would that work?

Cheers.
 
Yes, you will need the bottom bracket as well.
You can see on the picture of the one you linked that it is threaded on either end. Check that you have a thread on the inside of your frame for it to fit into, otherwise you might need something like this
 
Oh ok, I haven't taken it off yet, so I don't know for sure, but is it safe to say that as it was built for a one-piece it would not be threaded? Or is there a chance it could be? Suppose I'll just have to take it off and see :p
 
Im not too sure, its a bit before my time :P
Its possible that they sold the same frame with better components on it at a higher price so it might be ready for a newer style bottom bracket.
Only 1 way to find out really :)
 
it 100% wont be threaded , it is also a larger diameter than any threaded BBs

for the price of convertor cups and new cranks (might even be difficult to get correct chain line with those) you could probably buy a full second hand bike that would do you better than the old one...

what's the reason your swapping cranks ? if its because they arent spinning well then you can just service them with fresh grease or new bearings
 
Ah right, I might see if I can take it off tomorrow and have a look.

Basically I have had this bike for 11/12 years, not using it too frequently to start with, maybe just round the block a few Sundays in summer, then I left it for a few years, then used it quite heavily these last 3 years at uni. It has been subject to harsh weather conditions and has not been lubricated as often as it should have. I took it in for a new inner tube on Sat and they said that the whole chain section was beyond just 'rusted' and they replaced the chain and freewheel. The whole thing is just in really bad condition and I was thinking of just replacing the whole lot, so I'm also looking at front and rear derailleurs. Changing gears is not so great so I think they do need replacing. The service cost of the shop down the road was ridiculous so I thought I would have a go at doing it myself.

I'll see if I can get it off tomorrow, if I have time. I did a quick measure earlier, the length of it looks to be about 73mm, thats going along the top, one peddle side to the other, and the width looked to be about 50mm ish, but it was hard to tell as the crank arm/peddle arm bit is in the way.
 
OK, so I managed to get the crank off and have a look, and it was exactly like that video I saw, so it was pretty straight forward to take off, however it did reveal that it is threadless.





So I would need a threadless bottom bracket with some sort of cups then correct?

I am a little confused about what size I would need though. as it seems to me that it is about 73mm long and about 55mm wide. This doesn't seem to conform to any measurements I am seeing. Is this right?

 
This is probably the closest you'll get to it but you'll need to use ye olde cottered cranks.

http://cgi.ebay.co.uk/thompson-old-style-cottered-bike-bottom-bracket-cups-/270762787377

My opinion is go buy a tub of grease, clean all that old stuff out with a rag and repack the bearings with fresh grease. Tighten back up and it'll be good to go. If it's having trouble changing gear it probably just needs oiling and adjusting everywhere.

If you want to change the bearings then these should be the same:

http://cgi.ebay.co.uk/BOTTOM-BRACKET-CRANK-AXLE-CYCLE-BIKE-BEARINGS-1-4-STD-/220670805376
 
no, as said now by at least 2 ppl, get new bearings, pack them in with fresh grease and thats as good as that bikes ever going to go....
 
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