Help with bottom bracket replacement

[The Hofff]

I've got a Dawes Discovery 201 - had it a 8+ years now and bought it second hand even then
Modern one here: https://dawescycles.com/product/discovery-201/

I thought the front gear set was bent, but upon inspection the bottom bracket bearings were worn and so gave it a bit of pedal wobble which would catch the chain on the selector.

I've managed to remove it from the frame but was after a sanity check on what I need to go back in there.

The pedals stalks are the tapered type. The width of the frame section where it will go it 68mm (which seems a common size) and the link above tells me its a 123mm, so my guess is that I need something like the link below in a 122.5m x 68mm options - although these dont come with new bolts

https://www.chainreactioncycles.com/shimano-un26-s...
https://www.tweekscycles.com/shimano-un26-square-t...

I assumed the 68mm is just the frame section width? If I add on part of the old bottom bracket it makes it more like 70mm

Edited by The Hofff on Wednesday 10th June 20:15

[take-good-care-of-the-forest-dewey]

Pedal stalks...

Thank you... That's made my evening.

The size should be on the old bottom bracket. That should confirm the size you need.

However, given the measurements you've taken, it should be as you suggest.

68 x 122.5.

68mm is the width of the bottom bracket shell...i.e. The width of the frame where the bb fits.

122.5mm is the width of the square bit that spins (spindle) with the pedal stalks on (aka Crank arms).

Edited by take-good-care-of-the-forest-dewey on Wednesday 10th June 20:25

[defblade]

Have a look at SJS - they generally have good stock levels and a bit more choice than the "big" on-line sellers:
https://www.sjscycles.co.uk/square-tapered-shimano...
https://www.sjscycles.co.uk/square-tapered-other/

I've just fitted the cheapest IRD type after reading a lot of comments that Shimano BBs "ain't wot they used t'be" especially in terms of longevity, and many more comments that the bearings in the IRDs are very nice. It went in like a dream and is smooth as a smooth thing (tbf, the cracky-creaky Shimano that came out was 20 years and many 1000s of miles old... made like they used to be 20 years ago ).

[The Hofff]

Thanks both for your feedback and assistance.

I've ordered a replacement 68 x 112.5 which should be here tomorrow, I can then set too duck taping my pedal stalk and the round spikey turny thing back to the middle spinny bit... or cranks arms back on the spindle as you put it - You'd never have guessed that this is my first rodeo...

[defblade]

Have you got a crank puller? And the correct socket/driver for the BB cups??
Just asking, as otherwise you'll be stuck very shortly after starting this job...

[Barchettaman]

Hangabout - the width of the current BB spindle is 122,5mm but you´ve ordered 112,5mm?

Or was that a typo?

[Justin S]

defblade said:

Have you got a crank puller? And the correct socket/driver for the BB cups??
Just asking, as otherwise you'll be stuck very shortly after starting this job...

You will need a 10mm allen key or a 13mm thin wall socket to remove the bolt on the end of the crank. Also a 'square taper' crank arm extractor as there is 2 versions . The other is octolink or hollowtech, can't remember. All old stuff , although I have them both in my tool kit. You will also need a bottom bracket removal tool , as said above , which fits into the bottom bracket and usually use a lever arm from a socket set to unscrew.
When you use the crank extractor, make sure you screw it in and tighten with a spanner , then when you wind in the pin, to give it a tap with a hammer as you wind in and the shock should help free it off the taper of the axle.

[gazza285]

defblade said:

Have you got a crank puller? And the correct socket/driver for the BB cups??
Just asking, as otherwise you'll be stuck very shortly after starting this job...

Do you think he got the old BB out of the frame with the cranks still attached?

[Barchettaman]

gazza285 said:

defblade said:

Have you got a crank puller? And the correct socket/driver for the BB cups??
Just asking, as otherwise you'll be stuck very shortly after starting this job...

Do you think he got the old BB out of the frame with the cranks still attached?

It´s not clear from his posts whether the OP removed the BB/cups or just the crank arms from the BB spindle.

[gazza285]

Barchettaman said:

Its not clear from his posts whether the OP removed the BB/cups or just the crank arms from the BB spindle.

The Hofff said:

I've managed to remove it from the frame...

Looks clear to me.

[V1nce Fox]

I may be being a little old fashioned here, but I don't half prefer an independent spindle and cups to a cartridge.

[defblade]

gazza285 said:

Barchettaman said:

Its not clear from his posts whether the OP removed the BB/cups or just the crank arms from the BB spindle.

The Hofff said:

I've managed to remove it from the frame...

Looks clear to me.

Whoops, missed that. Guess he's got the tools then. As you were.

[Barchettaman]

gazza285 said:

Barchettaman said:

Its not clear from his posts whether the OP removed the BB/cups or just the crank arms from the BB spindle.

The Hofff said:

I've managed to remove it from the frame...

Looks clear to me.

Yeah, I agree, but without wishing to disappear up my own arse, they way I understood it was there could be a slight ambiguity about whether ‘it’ was just the crank arm.

Anyway, as you were.

[CharlieAlphaMike]

The Hofff said:

Thanks both for your feedback and assistance.

I've ordered a replacement 68 x 112.5 which should be here tomorrow, I can then set too duck taping my pedal stalk and the round spikey turny thing back to the middle spinny bit... or cranks arms back on the spindle as you put it - You'd never have guessed that this is my first rodeo...

Duct Tape is a very good option. Maybe a plasticy tie thingy would work too but I'd suggest putting some gluey sticky stuff (I think the professional people call it Threadlock or something) on the screwy things that hold the pedal stalks on the spikey turny thing.

[The Hofff]

Update: all done.

It was a typo, I did indeed order a 122.5 x 68 which arrived last Friday morning (Should have read the follow up comments from Thursday before going starting)

I didnt have a crank puller or the BB cup tooling - I really should read up more about these things before going for it. I've always managed to wiggle off the crank arms with some persuasion before so wasnt aware that was something that would have made my life a lot easier.

The non geared crank arm came off with some mechanical leverage from behind and a bit of persuasion.
Made my own tool to remove the BB cups, removed the now armless side and had a look - lots of rust and runny brown aged grease inside.
I managed to undo the BB cup from the geared crank arm side (with arm still attached) and slide out the arm and spindle together, rested in a vice an persuaded the spindle to remove itself.

All went back together fairly easily and feels a lot better, I didnt Loctite the spindle bolts so might whip these out again and apply some for good measure.