The bottom bracket has come loose on the chain side of my old Raleigh Team 501 / Cadet.

I can't get the crank off on the non-chain side, so am unable to get my big adjustable spanner in to tighten up the fitting on the chain side.

Does anyone know what size spanner I'd need? And is there a particular, thin one available that bike mechanics would use for this type of job?

Thanks in advance!

I assume your bike is older style cup and cone BB, with the drive side cup unthreaded. Yes, there is a thin spanner wrench that is used. Believe the size is 36mm. If you can get the drive side crank arm off, then you can use Park Tool Model HCW-4. I believe you can find thin open box style wrench, but don't know who makes them. As an alternative you might be better off taking it to your LBS and have them tighten it. Yes you will pay labor but that will be offset by not having to buy a tool,

Karl

Hiya Karl,

Thanks for your reply.

No, I think it's threaded on both sides. The part on the drive side has a couple of flat sides, and I'm pretty sure it is for tightening. Do you think it will still be 36mm?

Cheers,
Jim

This is a typical 36mm BB wrench for the right (drive) side BB. This one won’t quite work for you since it’s a box design and you’ll need an opened end version. I assume you can find one with an open end.

https://www.parktool.com/product/cra...ttom%20Bracket

Park does offer an open ended 36mm wrench for headsets. I assume this could work if you just need to tighten the BB cup. It may not be strong enough to loosen a stubborn BB Cup.

https://www.parktool.com/product/hea...tegory=Headset

also note, the threads in the right side are often reverse threaded

You might want to measure the width across the flats to ensure 36mm dimension.

I am not sure what kind of BB you have, but there is a chance that the flats on the chain-side are to just install/remove that side of the BB, while the all adjustment might happen at the other, non-chain end.

On a typical cup and cone BB the DS (drive side [chain side]) is a fixed cup installed and left alone. The NDS is the adjustable cup with a lock ring to hold the adjustment.
There are a number of less common C & C BB with adjustable cups on both sides like Phil Wood to allow tuning the chainline.

Most drive side bottom bracket cups with two flats are 36mm across the flats. Be aware that the drive side is a left-hand thread, so counter-clockwise to tighten. It's best to remove the crank arms to do this: drive side off to give access to the cup with a closed-end spanner (you may be able to access it with a 36mm open-end headset spanner, but it can be difficult to get the cup tight enough). Non-drive side off so you can adjust the bearings. If you've been riding it loose, it would be prudent to open up the whole thing and inspect for wear or damage, and then re-pack with fresh balls and grease. That would also let you (or, more likely, your bike shop) set the drive side cup good and tight with a professional grade tool, so it doesn't loosen again.

The “fixed” drive-side cup is very likely “left-hand threaded”. Even a cheap-a$$ plastic vernier caliper will be able to determine the wrench size required. Some of the Park BB tools have a cutout allowing tightening the drive-side without removing the drive-side crank arm and chainwheels. If the crank can be removed, a large crescent wrench will do the job. Most often, bearing adjustment is done on the non-drive side and may (probably) require two wrenches.

this is going to be a total pain and exercise in frustration if you don't remove the cranks first........