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New Shimno 105 BB a little tight, is this normal?


Soggy
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Just wanted to know if this is normal?

 

I recently converted my cartridge bottom bracket on my Merida to a cupped Bottom Bracket so my new FSA crank will work on it. I purchased a Shimano 105 BSA Bottom Bracket kit for it and it fits great. I noticed that the bearings themselves are a little tight in the bearing cups. Is this normal for new bearings and do they need to work themselves in and do I expect them to loosen up a little later after a few rides?

 

This kinda defeats the purpose of my carbon crank as them being a little tight now is adding more peddling resistance to my cycle.

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New bearings do have more resistance than most people think they should have. A new bearing has lots of grease inside and tight seals. As the bearing progresses through its life, the grease gradually works itself out under the seal. This is designed to be like that otherwise the seal will just burn off in a few revolutions. The grease is thus a consumable. As the grease is depleated, it eventually cannot seep out and the seal thus runs dry and rapidly burns its feathery edge away until it makes no contact anymore. Then the bearing is at its loosest, but also at the end of its life.

 

The little bit of resistance you feel with your finger is miniscule compared to wind resistance even at low speed.

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JB, if you wouldn't mind answering another related question I would be grateful; How do you know when its time to replace the bearings? The BB in my road bike is rather stiff - if the chain is off and I spin the cranks they only turn about 1 revolution before they stop. Does this mean the bearings are new or old? (2nd hand bike so no idea of mileage)

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JB, if you wouldn't mind answering another related question I would be grateful; How do you know when its time to replace the bearings? The BB in my road bike is rather stiff - if the chain is off and I spin the cranks they only turn about 1 revolution before they stop. Does this mean the bearings are new or old? (2nd hand bike so no idea of mileage)

 

Your avatar hurts my eyes.

 

To judge the condition of a BB do the following:

 

1)Remove the chain (you should have a master link on there so it won't be a hassle).

 

2) Put your ear on the top tube and make sure your jaw is out of the crank and pedal's reach.

 

3) Spin the crank.

 

A good BB will say shhhhhhhhh.

 

A bad BB will say rrrrrreplace me.

 

The rumble is unmistakeable.

 

 

 

Dont try and do this with the chain in place, it will confuse the matter. Don't turn the crank on the pedal, this introduces a secondary bearing into the sound.

 

It has nothing to do with how many revolutions the crank turns.

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Your avatar hurts my eyes.

 

To judge the condition of a BB do the following:

 

1)Remove the chain (you should have a master link on there so it won't be a hassle).

 

2) Put your ear on the top tube and make sure your jaw is out of the crank and pedal's reach.

 

3) Spin the crank.

 

A good BB will say shhhhhhhhh.

 

A bad BB will say rrrrrreplace me.

 

The rumble is unmistakeable.

 

 

 

Dont try and do this with the chain in place, it will confuse the matter. Don't turn the crank on the pedal, this introduces a secondary bearing into the sound.

 

It has nothing to do with how many revolutions the crank turns.

 

My crank also turns for the most, two revolutions, but there is no feedback. The bearings are smooth as silk and no sound comes from them. It does feel like there is thick grease in the bearings. I just didnt expect to hold back like it does as my old bearings have a very slight shhhh sound but have no play in them. Guess I must just work these new ones in then.

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Installed new Truvativ GXP BB on my MTB. My first time trying to do this. Followed instructions, right torque, grease where required. After installation the crank felt very stiff. I removed one spacer, no improvement (Old GXP BB had two spacer, no problem). Decided to leave as is and see if there is an improvement after cycling for about 200 km. No luck. Also thought that I over greased it, if that is possible.

 

 

 

Remove crank and BB. Found out that drive side bearing does not rotate freely in the external cup (could not turn by hand). Remove bearing, bearing rotating freely when remove from cup. Realised that the cup could be faulty (not right size). Decide to use the old cup with the new bearing. Problem solved. Crank spin like a dream.

 

 

 

So it seems internal diameter of cup to small and is �squeezing� the bearing, preventing it from tuning freely.

 

 

 

Glad I could solve the problem

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