Bottom bracket

[jim55]

I'm rebuilding a road bike and im replacing the square taper bb and rubbish generic crankset with a nice tiagra compact crank ,only thing is it's hollowtech and iv no idea what bb to get,.
It's standard size(69 mm width) and it's a trek alpha1.1 frame and I'm pretty sure it's original factory stuff,are a hollowtech bn the same , (69 mm ones) IL build it as far as I can however there's things IL get the lbs to do( it needs a headset and I don't even know what to buy or how to fit ,so IL b getting it done by a pro,but I can do bb and pretty much everything else,only thing I'm not sure of is headset ( as said) and IL prob get them to index gears as well..so any advice re BB😆iv got a wee list to buy so onto ebay

 

[si_c]

I'm rebuilding a road bike and im replacing the square taper bb and rubbish generic crankset with a nice tiagra compact crank ,only thing is it's hollowtech and iv no idea what bb to get,.
It's standard size(69 mm width) and it's a trek alpha1.1 frame and I'm pretty sure it's original factory stuff,are a hollowtech bn the same , (69 mm ones) IL build it as far as I can however there's things IL get the lbs to do( it needs a headset and I don't even know what to buy or how to fit ,so IL b getting it done by a pro,but I can do bb and pretty much everything else,only thing I'm not sure of is headset ( as said) and IL prob get them to index gears as well..so any advice re BB😆iv got a wee list to buy so onto ebay

If it is a threaded bottom bracket (I'm assuming so if it's square taper) then you need something like the BB-RS500 or BB-R9100 which are functionally the same. There isn't much difference between them really and the price difference is minimal

You do need a set of tools to properly fit, and they differ from the Square Taper tools, so if you're not sure you have them then i'd suggest getting the LBS to fit. It's not difficult, but there are issues around which tool you need for which BB and you may need adapters

 

[Cycleops]

If you’re buying a Shimano Hollowtech chainset it comes supplied with the appropriate screw-in BB bearings (may not be all models now so check) There is only one length spindle so you get three plastic spacers which you add or omit.
Easy peasy to fit you just need the Hollowtech BB spanner and a little plastic tool for crank preload ( can’t remember if you get one supplied, the BB spanner has one on the end with some), plus of course a 5mm (I think) Allen key for the LH crank.

Good luck.

 

[si_c]

If you’re buying a Shimano Hollowtech chainset it comes supplied with the appropriate screw-in BB bearings (may not be all models now so check) There is only one length spindle so you get three plastic spacers which you add or omit.
Easy peasy to fit you just need the Hollowtech BB spanner and a little plastic tool for crank preload ( can’t remember if you get one supplied, the BB spanner has one on the end with some), plus of course a 5mm (I think) Allen key for the LH crank.

Good luck.

There are two sizes of HT2 cups so you need an adapter for the smaller one, which tends to be most road variants. It sometimes comes in the box but not always.

 

[Ajax Bay]

68

 

[fair weather cyclist]

have you removed cranks and square taper bb already? If not, you need a specific tool for it as well

 

[Cycleops]

Good point FWC. Might I suggest the fifty quid Decathlon tool kit which has tools for both plus a quite few other useful bits, including the one needed to remove your existing ST BB.

 

[Ajax Bay]

it's a trek alpha1.1 frame and I'm pretty sure it's original factory stuff

Take care that you assess how much all this investment in a working Trek will be and that it's worth it, if you're going to get an LBS to do some of the work. As soon as you can't put in the labour as '0' it'll add up (eg headset and installation). The original spec with non Claris parts eg chainset, BB and cassette were put together for a reason.
lots of fun if you're doing it. Surprised the headset needs replacing but depends on how the bike's been stored.

 

[Dogtrousers]

Take care that you assess how much all this investment in a working Trek will be and that it's worth it, if you're going to get an LBS to do some of the work. As soon as you can't put in the labour as '0' it'll add up (eg headset and installation). The original spec with non Claris parts eg chainset, BB and cassette were put together for a reason.
lots of fun if you're doing it. Surprised the headset needs replacing but depends on how the bike's been stored.

For some values of "fun"

 

[PpPete]

There are two sizes of HT2 cups so you need an adapter for the smaller one, which tends to be most road variants. It sometimes comes in the box but not always.

actually 3
I suggest to stick with the original "tiagra level" one. That takes the regular HT2 tool
This tool for example will do the regular size and the 9000 series - but not the BB-R60 which is supposedly Ultegra level (although actually a POS)