Change of BB for upgrade

[Jimmy Welch]

Hi All I'm thinking of upgrading my drive chain to 105 11 speed I currently have Claris 8 speed with a square taper bb BBS 15 68 x103 if I go to 105 what bb will I need , also if there's an option for a threaded bb rather than a push fit just for ease of fitting that would be preferable

 

[Cycleops]

The 105 11 speed chainset is a two piece Hollowtech (spindle is attached to the drive side crank) and comes with screw in outboard bearings, at least my chainset did. Don’t know if there’s an option for PF so check with the seller. Presume you have a threaded BB.
Heres a run down of the process of changing it over from RJ:

View: https://youtu.be/TcyaSEAhI5k

Just be aware the Hollowtech bearings will have nowhere near the longevity of the old ST BB.

 

[Jimmy Welch]

The 105 11 speed chainset is a two piece Hollowtech (spindle is attached to the drive side crank) and comes with screw in outboard bearings, at least my chainset did. Don’t know if there’s an option for PF so check with the seller. Presume you have a threaded BB.
Heres a run down of the process of changing it over from RJ:

View: https://youtu.be/TcyaSEAhI5k

Just be aware the Hollowtech bearings will have nowhere near the longevity of the old ST BB.

Cheers for this , my pal runs 105 on his carbon frame and I'm sure he has push fit bb , as a second point , maybe a daft one if the bb bearings are external do the cranks hang slightly further away from the bike , and if so is the bikes set up changed

 

[T4tomo]

The type of BB (as in screw fit or press fit) depend on your frame, if you have a BB shell with threads in it get, then clearly you need a screw in BB and vice versa. You select the specific BB as to what will then fit with your chosen crankset. if you look at the spec for the crankset - it will / should show you compatible BBs to use.

maybe a daft one if the bb bearings are external do the cranks hang slightly further away from the bike , and if so is the bikes set up changed

as the bearings are external you can attach them to your rear rack

it should all be fine as Hollowtech II BBs have a standard chain-line measure and your old ST BB would have been mimicking this. there isnt an axle length measure to worry about as there is in the world of ST

 

[T4tomo]

https://bike.shimano.com/en-EU/product/component/shimano105-r7000/FC-R7000.html

scroll down the product specs and you get to

its not that difficult to remove old and fit new, especially threaded. just need the correct tools and be very careful not to cross- thread it. Watch some relevant park tool videos so you know which direction thread each side has. Pop a bit of lithium grease on the threads as it goes in, makes getting the bugger out again easier....