Eccentric BB newbie

DannyJames

Just building up my singlespeed into my new frame which uses an eccentric bottom bracket held by 2 allen key bolts never used one before so anything i need to know? My concerns are,

Does any of it need greasing?
Is there a preferred position for the cranks when tensioned to the front or rear of the bb etc?
How tight do i need to go on the bolts to hold it in place?
How much chain tension?

Anything else?

Cheers in advance

nicklouse

not really.
as tight as needed
1/2" vertical movement in the centre of one chain run.

bikaholic

1. Yes, I lightly grease all mating surfaces. You will understand the importance of this if your bike goes through a lot of water (ie mud and "salts" from dirty water and calcium carbonate from clean tap water).

2. Put the cranks in whatever position is needed in order to insert the tool to rotate the EBB offset shell. I rotate the shell in the direction which tightens the BB threads as if it was held stationary (ie anti clockwise when facing the NDS).

3. Tighten the two pinch bolts like you would do on a Shimano HT2 NDS crank arm: a bit at a time on each bolt in order to maintain a even clamping force. Then mark the position of the EBB shell relative to the frame with a permanent marker - if the marks don't line up after some usage then you'll know that it wasn't done up tight enough the first time around.

4. Chain tension: as tight as possible without binding. To gauge this point, fit the chain and spin the cranks.

If you are extremely lucky then the rear cog and the chainring will be perfectly circular giving you an even tension for a 360 spin of the crank. Most of the time it's not, so try and find the point inbetween the 360 spin where it is at the tightest and then adjust the EBB shell to that point.

In my book, if you can grab the chain and squeeze it for more than half an inch then it's too loose.

DannyJames

Cheers for the reply's

Some good advice there will have ago when i get chance as this is now the last part of my new build

Monty Dog

Lay-off the chain tension - it only needs to be tight enough to prevent the chain coming off - too tight and you'll wear out the chain, sprocket and bearings more quickly as well as being noisy. 1cm vertical play mid-way along the chain is enough.

nicklouse

DannyJames wrote:

Cheers for the reply's

Some good advice there will have ago when i get chance as this is now the last part of my new build

be aware that there are many different ways of clamping (holding) the sleeve in place.

so for any specific answers you will need to ID it or post pics.