What size Bottom Bracket do I need.

[jay clock]

I have a Trek 2.1 like this. http://www.evanscycles.com/products/trek/21-compact-2011-road-bike-ec023946

I know it is Hollowtech II and presumably English thread. I ordered one of these but it is too small http://www.chainreactioncycles.com/shimano-ultegra-6800-bottom-bracket/rp-prod108701

Presumably I need a 73mm? Can anyone point me to what I need? Most retailers just say English vs Italian and quite a lot are listed as 68/73mm as if one size fits all....

Many thanks

 

[ayceejay]

If you have a triple chainset the double will be too short.

 

[jay clock]

Being Hollowtech II there is no difference, you just get a cup that screws in each side. The axle forms part of the chainset......

 

[User6179]

Standard HT2 68mm bottom bracket , The one you have linked seems to be the one you need but going by the comments the standard HT2 tool wont fit it .

 

[jay clock]

The on I have is too small in diameter. I have the tool that fits the one on the bike and the tool is too bag for the replacement one I bought. Will post pic in a mo

 

[jay clock]

bb

• jay clock
• 13 Dec 2015

That shows my tool (that fits the BB on the bike) around the one I bought here http://www.chainreactioncycles.com/shimano-ultegra-6800-bottom-bracket/rp-prod108701

I know it looks like the tool is hovering above, but it is not. So the equivalent of using a 15mm ring spanner on a 12mm bolt....

 

[jay clock]

I hav realised the 68/73mm relates to the width and mine does appear to be 68mm. hard to measure exactly. It is the cups on the one I bought (described as 68mm English) that are too small for the shell

 

[Sea of vapours]

Have you removed the old bottom bracket, and do the new cups not fit the thread in the frame? I'm only asking since if it's just the outer diameter of the end section, where the tool fits on to tighten the cups in place in the frame, which you're saying is too small, then that's because there's an adaptor which comes with the tool - or maybe with a groupset - to make it fit. (Looks that way from the photo you've just posted.)

So if a) the cups will screw into the frame, but b) the tool you have won't fit on the cups to tighten them up, then I think what you're missing is the plastic adaptor (which my BB tool has). If the cups themselves won't screw in / don't fit then ignore all the preceding though...

 

[jay clock]

Cups won't fit in. I stripped the whole thing down a couple of months back and it was an "oops" moment as the cups were too small

I am puzzled as the bike is pretty standard mainstream bike.....

 

[jowwy]

You need to post a picture of the new cups not fitting the shell so we can see.

6800 bottom bracket will fit a standard 68mm english bb shell......but it comes with a extra connector which fits onto the tool so you can screw the cups in.......either that or you got shimano push fit cups that go into a bb30 bottom bracket, which means the 6800 would be way too small and the wrong bottom bracket

 

[jay clock]

OK if i have done this right there should be three pics. Most important is the old cup vs the new cup side by side.

new cup vs old cup

• jay clock
• 13 Dec 2015

Old cup is approx 41mm outside diameter and new one (purchased from CRC and described as 68mm English) is about 37mm. The new wrong size is on the left and is back, right hand of the pic is the current one and is silver

Also pics of the new whole BB

new Bb wrong size

• jay clock
• 13 Dec 2015

old bb with tool

• jay clock
• 13 Dec 2015

plus the current left hand cup (non drive side) in situ with the tool in place. (Tool is too big for the new cup)

Comments very welcome !

 

[Erudin]

You can buy an adapter (search for: TL-FC25) for your old bracket-tool.

Look at the Q&A's in the link below for more info:

http://www.wiggle.co.uk/shimano-bb-r60-ultegra-6800105-5800-hollowtech-ii/

 

[Sea of vapours]

Can you post a photo like the top one, only with the two pieces turned 90 degrees such that the inner, threaded parts face each other and are side by side and visible?

 

[jay clock]

You can buy an adapter (search for: TL-FC25) for your old bracket-tool.

Look at the Q&A's in the link below for more info:

http://www.wiggle.co.uk/shimano-bb-r60-ultegra-6800105-5800-hollowtech-ii/

The adapter was provided with the new (too small in diameter) BB and allows me to use the tool with those cups. But the cups are too small for the shell.

 

[jay clock]

Can you post a photo like the top one, only with the two pieces turned 90 degrees such that the inner, threaded parts face each other and are side by side and visible?

will try and do shortly