3

I'm trying to restore vintage bicycle I happen to own. I came to the stage of pulling cranks off and it apperas that I can't find the appriopriate tool to do that. Could anyone advice me on this? I attached some photos of the thread in the crank.

enter image description here enter image description here enter image description here enter image description here

EDIT

As some pointed out in comments there is separate thread in the bottom bracket axle. It's a square taper bottom bracket and the crank is bolted onto it just like with modern square taper BBs. In other words there is a thread in the axle and a separate, bigger one in the crank. The problem is a thread gauge. I thought I could find appriopriate puller online but I failed.

EDIT 2

I've taken a picture of bicycle itself, and also I managed to scrape black paint from a little plate riveted to the headtube uncovering name of the bicycle manufacturer. Apart from that, and the facts Pashley is a British company, I don't know anything about bicycle's origin.

enter image description here enter image description here

Improve this question
7
  • Aside - can you simply avoid removing the cranks ? Is there a compelling reason to do so?
    – Criggie ♦
    Aug 20, 2022 at 13:05
  • 2
    Do you have other information about the bike, like how old it is, country of origin or brand? What style of bolt was in that threaded hole? Did you unscrew anything else? I’ve never seen crank like this but those details may help someone.
    – ojs
    Aug 20, 2022 at 16:24
  • 1
    @Criggie yes, they're rusty and I also want a belt drivetrain.
    – Daniel
    Aug 20, 2022 at 20:56
  • Is asking a LBS out of the question? When I was restoring my bike I wasn't sure which way to unthread the BB, but I knew the make and year of the frame. Hopped in the LBS, asked, and got confirmation it's just good old BSA. If the bike is common in your area like mine is where I live then it's likely the shop could disassemble it blindfolded.
    – jayded-bee
    Aug 21, 2022 at 0:05
  • @Daniel: you cannot do a belt drive on any bicycle, they require a special detachable stay so you can feed the belt thru the rear triangle. It's not an option here.
    – whatsisname
    Aug 22, 2022 at 4:41

2 Answers 2

Reset to default
3

It appears the extraction threads are 10mm. That wouldn't leave room for a tool to be hollow and have something running through them to push against the spindle, which is hollow.

I'm not totally sure what the intention here is but it's probably something along the lines of just using any bolt that's the same thread as the extraction threads, screwing it in and letting the tip ram against the spindle.

If you wanted to be gentler on the spindle, at least for the sake of testing the theory, you could get a grub bolt the same size as the crank bolt and let the extraction bolt ram against that instead.

Make sure the threads on the crank are actually integral with them and not some kind of cap.

A slide hammer or pickle fork could also do it, but the former can damage the bearings and the latter the crank, BB, and in some cases the frame/paint.

Improve this answer
6
  • 1
    I was thinking the same, even tried with M10 bolt, unsuccessfully. The thread in the crank is really thick and I couldn't find apprioriate bolts online. Hence the request for help.
    – Daniel
    Aug 20, 2022 at 20:58
  • @daniel The source and age of the bike is important - its unlikely to be metric unless its french based on the apparent age. You may have to resort to heat-and-beat with leverage, or carefully carving the whole thing off destructively. Suggest this is a last-last resort, because you might not find a crank to suit this square taper (they're not all interchangeable) and have to refit this one.
    – Criggie ♦
    Aug 20, 2022 at 22:40
  • 1
    @Daniel it could be m10x1.5. that part you can use a thread pitch gauge to unravel.
    – Nathan Knutson
    Aug 20, 2022 at 22:45
  • 1
    @jayded-bee I believe we can see the axle has internal threads in the second picture. If it doesn't work like this then I have no idea what's going on, but it all makes sense to me that it would.
    – Nathan Knutson
    Aug 21, 2022 at 2:06
  • 1
    @jayded-bee there is square taper axle with it's own thread, as Nathan pointed out. It looks like it works the same way as with modern square taper bottom brackets, you screw puller into the crank and turn the inner bolt to push it against axle. The only problem is my standard puller doesn't work here and I think I need a special one, meant for this type of crank.
    – Daniel
    Aug 21, 2022 at 8:40
0

First option is to ask your usual LBS if they have a tool for the job. Most older bike shops have weird tools that get used once a decade.

Avoid bike shops that sell running shoes - you want an old shop that does touring bikes and has been around for decades. Ideally it should be packed full, no wide-open aisles.

If you're a regular customer, they might not even charge. Even if you got 1/4 hour labour, its still cheaper than buying a once-off tool.

Are you confident there's a normal thread cut inside the frame? One for which you can buy a modern cartridge BB?

If so, I'd go destructive.

  1. Heat the crank arm with hot air for 5 minutes, then squirt liquid oil into the middle. You're aiming to heat the outside and cool the inside axle. Use two levers to push the crankset off the frame (two big screwdrivers or crowfoot or small crowbars)

  2. Cut the whole thing off with an angle grinder while taking care not to ding the frame. I'd do a plunge cut straight across the axle with a cut-off disk, and keep cutting down till the chainring has a cut in it. Then use a thin wedge like an old screwdriver in the slot to widen it and lever the crank off the bike.

You'll probably never use this special crank-puller again, and there's an excellent chance the square taper is not-quite normal so you'd need a replacement BB axle anyway.

Downside of this is that reverting to stock will be impossible, so you need to ensure all the new belt-drive parts will fit before committing.

Improve this answer
1
  • 1
    I'll go and ask at the shop, if I find one first, apart from Evans Cycles (I'm in the UK). I'd rather not go too crazy with it, as you said, in case I want to keep original bottom bracket, but as a last resort I have my angle grinder ready. The thing is I don't know anything beyond the fact the crank sits on top of square taper axle, I can see it after removing crank bolt.
    – Daniel
    Aug 21, 2022 at 19:46

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.