Bicycle Mechanics - '70s Bridgstone Crankset Removal: Can't!

So, I understand modern crankset removal. Awesome. Trying to update my super old Bridgestone crankset due to it being bent and causing huge problems in a crunch. The biggest problem is I can't figure the thing out. it's nothing like modern cranksets. There's one screw. "Start with undoing that." Nothing. The scre itself seems to be welded ot part of an interior piece that doesn't move. Poke, prod, pull. Nothing. There's no endcap covering anything (where it would be normally is solid metal). I searched the forums and found one post with my same bike, but the OP never responded. You tube is a no go as well. Ideas folks??

My bike is a 1971 Bridgestone. There is no name as far as I know. But I guess that was the C. Itho & Kabuki era. Pictures for bike & crankset below.

OK you have cottered steel cranks. The pin is a tapered wedge that engages a flat area milled into the spindle. Removing cotters is sort of a lost art but there are a few tutorials available here (https://www.google.com/search?q=removing+cottered+cranks&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a) on removing them.

The key is you have to remove or back off the nut, then drive the pin out either with a press or a hammer. If you go the hammer route it's important that you support the crank arm both to protect the bearings, and to concentrate the hammer's energy. Then use enough force to drive the pin out in one shot. Otherwise you'll be mushrooming the bolt rather than driving the pin.

If you've already mushroomed the nut, saw it off flush then use a punch to drive it out (after properly supporting the crank arm).

Your bike has a cottered crank and the best way to disassemble it is to remove the nut and use a cotter press to push the cotter pin out... it only feels like it is welded in place and they can be very resistant to removal.

Alternatively, you can use a hammer and a punch... the crank arm needs to be braced from below or most of the force from the hammer will be wasted and in cases where you want to re-use the parts, prevents one from bending the spindle.

If you use a hammer you want to be firm and take out the pin in a single shot as tapping away will only mess up the pin.

Your Bridgestone also appears to use Aluminium lugs which is a feature that is rather unique to Bridgestones of this era.

I LOVE THIS FORUM. You two are amazing. Thank you. It will be a bit more work than I thought then. No big, at least I know it. I guess this means I have to change all of the innards of the BB if I want to use a modern crankset. Is this a terrible idea?? Not that I'm sure this bike is worth much, but would that hurt it's value? I mean I adore the thing and wouldn't sell it anyways. Just kind of peace of mind thing.

Sixty Fiver: Is that bad or good?? And I knew it was lugged, but how did you know it was alum?

I LOVE THIS FORUM. You two are amazing. Thank you. It will be a bit more work than I thought then. No big, at least I know it. I guess this means I have to change all of the innards of the BB if I want to use a modern crankset. Is this a terrible idea?? Not that I'm sure this bike is worth much, but would that hurt it's value? I mean I adore the thing and wouldn't sell it anyways. Just kind of peace of mind thing.

Sixty Fiver: Is that bad or good?? And I knew it was lugged, but how did you know it was alum?

I have come across a good number of Bridgestone bicycles with these aluminium lugs and you can check this with a simple magnet... because the steel frame tubes run into the lug there will be a slight pull but will be a major difference between that and the main tubes.

Can't quite see the seat post well enough in the picture and if there is no real clamp you will find that the seat post is a quill type with the nut located at the top of the seat post beneath the saddle... because the aluminium castings do not flex like steel this quill post design is a requirement.

Upgrading the crank to a modern one is a good idea... esiest method would be to install a cartridge bottom bracket and square taper crank set and am sure that if you keep your eyes posted in the sales forum something suitable will present itself and people always seem to have spares stashed away.

Just checked, and yes you're right. Nice trick with the magnet. And yes, the seat post is most definitely a quill one. That's one of the first things I found out. Pretty neat I must say. Thanks for the advice about the BB. I was trying to figure out what to look into next, I guess that is applicable and suitable to me needs. Hell of a learning curve bikes are. Thanks again.


I have come across a good number of Bridgestone bicycles with these aluminium lugs and you can check this with a simple magnet... because the steel frame tubes run into the lug there will be a slight pull but will be a major difference between that and the main tubes.

Can't quite see the seat post well enough in the picture and if there is no real clamp you will find that the seat post is a quill type with the nut located at the top of the seat post beneath the saddle... because the aluminium castings do not flex like steel this quill post design is a requirement.

Upgrading the crank to a modern one is a good idea... esiest method would be to install a cartridge bottom bracket and square taper crank set and am sure that if you keep your eyes posted in the sales forum something suitable will present itself and people always seem to have spares stashed away.

OK you have cottered steel cranks. The pin is a tapered wedge that engages a flat area milled into the spindle.

Yep. Here's a couple more tips from the late guru of all things bicycle: http://sheldonbrown.com/cotters.html

I've removed cotter pins with a hammer by loosening the nut until the end of the pin and nut are flush. Then tap with the hammer, so that it's hitting the nut and pin at the same time, spreading the load to the end of the pin & the threads at the same time. If the BB is getting tossed out, you won't care about what happens to the bearings. The shock might even help loosen the cups a bit if you're lucky.
This isn't the perfect method, but it usually works.

Thank goodness cottered cranks are a thing of the past.
I remember when my brother and I tried to remove one when we were about
10 years old. We tried and tried and tried but couldn't do it, so we took it to a LBS
to do it for us. The "mechanic" took it to the back, put it in stand and started
wailing on it with a hammer. You could hear pieces of metal hitting the floor of what
I assume were parts of the pin. I love hollowtech :)

I had a bike like that once, all you have to do is remove the nut, spray some WD-40 or some other lube in the pin, and hammer the wedge out.

I had a bike like that once, all you have to do is remove the nut, spray some WD-40 or some other lube in the pin, and hammer the wedge out.

Once...

If you are lucky all you need to do it hit it once and the pin will come out but this is not always the case... pins can corrode / shift and get jammed so badly you might think they were part of the spindle.

In some cases where I was not going to be re-using the cottered crank I have removed them with a cut off wheel.

http://www.youtube.com/watch?v=mybfNsm1XwM