Mick F wrote:….It's a fairly recent development to standardise BB shells and threads in general. When I was a kid, I knew that "bicycle threads" were very different to normal ones. Even normal spanners wouldn't fit a bike, but they do now.
'Normal spanners?' Recent standardisation? Not sure I agree with any of that.
British cycle threads have been standardised (BSC) for about a century. The reason your 'normal spanners' didn't fit bicycle parts is because there is no such thing as a 'normal spanner'. Spanners in BSW/BSF sizes (not AF
, not metric ) also fit BSC threaded parts when they are made to standard. The standard covers axles, pedal threads, seat binder bolts etc as well as BB and headset threads. Most of this standard is no longer used, we are left with pedal, BB and headset threading, along with quill stem sizing and main tube sizes.
Raleigh's use of 26tpi bottom bracket and headset threading is viewed as a proprietary standard but it was arguably more in spirit with the rest of the BSC standard, in which 26tpi was the norm, not 24tpi. But 24tpi won the day for headsets and BBs (in BSC) and this is now the ISO thread pitch for bottom brackets and headset threading (unless it is 1-1/8" threaded in which case it is 26tpi again....
Arguably Raleigh abandoned the use of their own BB and headset threading in response to pressures of manufacturing cost. Faced with the choice of manufacturing their own parts (which were of excellent quality for a very long time) or buying commoditised (BSC, JIS etc) partsmanufactured in low wage economies they eventually chose the latter route. Interestingly they tried for a while to make 26tpi parts more cheaply, using a plasma nitriding process to make hard bearing surfaces. This was entirely inappropriate technology to use in highly loaded bearings because the bearing surfaces would quickly suffer subsurface fatigue.
Today every other 'designer' seems to fancy a go at a new BB or headset type, which they often have the brass neck to refer to as a 'standard'. Most of them are rubbish. Metric is the new 'normal' so most bike parts are made with metric sized hexagons etc on them, but this isn't necessarily part of any standard, whereas BITD those 'funny-sized spanners' were
To fit a HT-II BB to a narrow BB shell, I recommend that you use a MTB type BB assy (which has longer cup threads and comes with spacers) and space those cups to suit the (road?) crankset you intend to use. NB you will probably have to do something with the centre sleeve to make it fit.