Transmission database - for all your crank / bb / bottom bracket questions

I have a feeling it’s ISO. I think on the SR 80s cranks, 130 bcd was JIS, and 144 was ISO. Will give it a try on my SR bb which is ISO, first.

I'm just going on what I found on Velobase (which isn't infallible):
"To confuse issues SR Decided to make these cranks compatible to Shimano Dura Ace or Campy, with differing Crank Tapers to match and possibly differing BCD measurements. To further confuse things, the model type was not stamped on the crank arms - so compatibility will be a matter of trial and error."

From that, you may be on to something BCD/taper-wise...

Thanks so much for the resources, much appreciated!

To complicate matters, I took a look at the bb30 frame today. The token bottom bracket in it that came from the factory looks to basically be a reducer made of aluminium that is pressed into the frame, that then holds smaller bearing that allow the use of Shimano cranks. I've attached a photo of the bottom bracket with crank removed.

Should I a) punch the bearings out of the reducer and replace them with the same bearing type, or b) remove the whole unit and replace with a larger bb30 bearing kit like this and then a adapter like this?

Or does it not really matter? Neither seems like a great solution tbh

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Is this the Winter bike with the creaky BB you mentioned in your first post?

The creaking is likely from the interface between the adaptor and the BB30 bearings, rather than the adaptor bearings being shot.

Regardless of which I doubt the adaptor's bearings are replaceable, ie you would replace the whole adaptor.

If you are using 24mm cranks, you'd be better off with a Praxis Works convertor BB: it's a much better design as a) the two parts are threaded together so will be aligned and b) it replaces the BB30 bearings so there is no interface to creak, hence why they call it a "convertor" rather than an "adaptor".

In order to remove the BB30 bearings, you'll first want to remove the adaptor: fingers crossed it wasn't bonded in by a previous owner, in an attempt to solve the creaking...

Yeah it's the same bike. I've seen the praxis works converter, and love the concept, I just don't love the price. Their website seems to hint that you shouldn't really attempt to replace the bearings in the converter, you should just replace the whole converter unit. Do you know of that's true, or once I've bought the converter can I just replace the bearings as they wear out?

It is "nice but pricey", I suppose it depends how much you value a silent BB?

I'd be inclined to take their word for it regarding bearing replacement, but BB aren't something you replace frequently: two/three years?

Knocking an adaptor out won't do your BB30 bearings any good, so you'd be advised to replace them at the same time and every time you change them the tolerance of the shell will deteriorate.

So you need to add up the cost of BB30 bearings + adaptor + time & trouble vs. a convertor and make a judgement based on that.

my bb knowledge isnt great but asking a seller on ebay if the campag bb for sale is english threaded (?) his reply is 'it is in fact 1.370" x 24 TPi not 1.375" x 24 TPi which is English thread'. will 1.370" x 24 TPi still work?

This should answer your question?

https://www.sheldonbrown.com/cribsheet-bottombrackets.html

Quick question for the technically minded among us. Running 1x10 on a surly pacer, 68mm bsa, ring on outer of a road double with q factor of 156mm, I have a un55 in the shed, axle is 113mm, too long?

Tifosi toss. Just had one of these jammed in a frame. The cups are so soft. Don't think I've damaged the bb threads, but the sealed brackets toast. Chewed the splines too. I had to use a cone spanner to push the removal tool in held through the bb with a qr skewer to get it out. The alloy is mush. Utter crap. Cleaned the threads inside the shell again, and the new tifosi is just as bad. Campagnolo from now on. Anyone else had experience of this brand. Seems omnipresent, God knows why...

Bought iso version, didn't even bother to install when I just put cranks on spindle to see. Not iso one fucking bit.

I'll get a miche primato evo if nothing turns up here. Must admit, didn't like how if fitted the taper either.

The length of the BB is dependent on the cranks: two different cranks can achieve the same chainline, with different length BB.

You need to break out the internet to find what size BB is recommended as OE.

You'll then want to bring the cranks in a little to sit the chain in the middle of the cassette (assuming you use the outer ring position).

Thank you. Thought so, but wanted to check for sure.

Found it, 110mm recommended with double, so 107mm to bring the line in a bit?

Assuming your cranks are Shimano standard, then the chainline measured between the two rings is 43.5mm and 46mm for the outer ring.

So in an ideal world you'd want a 105mm BB, but 107mm is probably as close as you'll get and will certainly be an improvement.

Ta. Will get one ordered.

so.
double shimano 130bcd, 73mm bb, square taper jis, chainring on outer position.
for 50mm chainline would need a 118mm bb? (46mm chainline - 110mm bb -> 50mm chainline 110+4+4mm = 118mm)
not sure though if the 130mm bcd crank will clear the wide mtb chainstays (genesis io) but ideally I want to be able to use my choice of 130mm chainrings (42/43/44) with a 16t rear. (might also go bolt on cog).
many thanks.

Yes, looks good to me.

The spider and rings should clear the chainstays: MTB triple chainline (measured to middle ring) is 47.5mm.

If the cranks are long, you might have a problem at the pedal end though.

I have a genesis day one frame I was going to run fixed for some commuting and light off-road duties.

I have a philwood sprocket and I was going to run a Miche advanced crankset up front.

The day one has a 68mm BB shell, 135mm rear dropout spacing and a 47.5mm chainline (so I've been told) and the Miche chainline is 42mm with a 107mm BB (so I gather...).

So... with a difference of 5.5 on the chainline I need a BB 11mm bigger, a UN55 118mm in other words?

Is this correct in theory? I've never had to do this before.

so I've been told... so I gather...

Measure them: a quick Duckle finds different versions of the Day One.

Otherwise your theory is sound.

Makes sense, cheers.

Hi all. I’m new hear but have found LFGSS invaluable over the years. I’ve been lurking!

I’m on my new project which will be built around a Burls custom frame. It will be singlespeed with (I hope) a custom Phil Works rear hub (still working this out with PW).

I would like to use the white industries crank with external BB. Cos it looks good, innit. WI say I can use a TSR chainring (which is made for 11 or 12 speed) with a 3/32 chain. I’m dubious and wonder if anyone here has any practical experience.

Alternatively, is there another company that makes white industries compatible chainrings? Can’t for the life of me find one. I’m aware of the XX1 adaptor but same issue re 11 / 12 speed.

Thank you

Anyone shed any light on this, just got a beater lugged frame, tried a bb in only to find it just pushed straight in, did older frames have a slightly larger bb?

Italian?