Bottom Bracket

[Kano]

I have a new one.

When we took our bikes to get pedals, bike guy said, this bike's bottom bracket is loose. I could fix it for $10.

I chose to take it to LBS where I bought it and get free service all year -- $10 to spend on something else, yes?

So, when I took my bike for new tires, and to ask "why do my elbows feel like old lady elbows when I ride" (that was pre-pedals) and we ordered a new seat post (your seat post is too high lady! No, it needs to be there, or I hurt. Okay, then it's too short, so we need to order you a longer one. Well, that came in on Friday, so Tuesday I went to pick it up. Brought bike along -- remember, pedal-bike-guy said the bottom bracket was loose, so I wanted that checked out.

Bike guy put new seat post on seat and into bike, and that was good -- then checked out the "clunk" I told him was there, and gave bike to service guys. They looked at it and said, we wanna keep it and replace that bracket.

SO

Today I rode for the first time -- ride is hugely different. SO, besides being the thing that the pedals and gears are attached to, what IS this bracket, and what did it do for me to have a new one? Or is it just in my head and it's ME that rode hugely different today?

Karen in Boise

[DebW]

I have a new one.

When we took our bikes to get pedals, bike guy said, this bike's bottom bracket is loose.

Bike guy put new seat post on seat and into bike, and that was good -- then checked out the "clunk" I told him was there, and gave bike to service guys. They looked at it and said, we wanna keep it and replace that bracket.

SO

Today I rode for the first time -- ride is hugely different. SO, besides being the thing that the pedals and gears are attached to, what IS this bracket, and what did it do for me to have a new one? Or is it just in my head and it's ME that rode hugely different today?

Karen in Boise

It's that short round tube mounted horizontally at the bike's low point. Threaded on both sides to take bearing cups. The right side has a "fixed cup", the left an "adjusting cup", both right-hand threaded on the majority of bikes. The crank spindle goes through it. Bottom brackets typically take 11 1/4 inch bearings on each side. If your bottom bracket was loose, the spindle and both crank arms could wiggle back and forth, resulting in clunking and chain wobble and poor shifting and other dastardly things.

To test a bottom bracket, grab a crank arm and try to move it in and out relative to the frame. Do this with both arms at several different position. Any movement at all means that the bottom bracket is loose and needs to be adjusted.

[DebW]

Something went flaky before I finished the previous post. Continued...

Remove the chain from the chainrings (drop it to the inside) and spin the crank. It should spin very freely. Any binding at all means it is not adjusted properly and probably needs to be repacked with grease. You can actually feel the BB far better if you remove both crank arms first. This requires a special crank-pulling tool and a fair bit of muscle. Unless you have a seal cartridge bottom bracket, the bottom bracket should be opened, cleaned, and repacked with grease periodically (probably once per year is enough for most people, twice for high mileage riders). Opening the BB takes a lockring tool and pin spanner to open the adjustable cup. The fixed cup should never be removed unless it is being replaced or has come loose. Fixed cups can occasionally rarely come loose.

Did I cover everything?

[Kano]

Thanks, Deb!

I'm glad I have an LBS who could fix that for me! It sounds beyond my current skill level, though maybe some day!

So, this repair I had done really DID make the ride smoother than ever?
I came very close to stopping in the shop on the way home to tell them THANK YOU -- cuz they did such a good thing to my bike!

Cool!

Karen in Boise

[DebW]

Thanks, Deb!

I'm glad I have an LBS who could fix that for me! It sounds beyond my current skill level, though maybe some day!

So, this repair I had done really DID make the ride smoother than ever?
I came very close to stopping in the shop on the way home to tell them THANK YOU -- cuz they did such a good thing to my bike!

How long had you been riding with it loose? Must have been awhile if it needed to be replaced - probably munged the spindle and chewed up the cups. The big worry there is that the threads in the bottom bracket could have been damaged. If they were, it's either retap them and hope or replace the whole frame. You really should be checking this new bottom bracket for tightness periodically now. Take it in immediately if it gets loose. If it loosens up more than once in the next several months, I'd be very suspicious of the threads and ask your LBS to check them and maybe retap.

[Kano]

How long had you been riding with it loose? Must have been awhile if it needed to be replaced

I've had the bike since the end of April. I remember having them look at it because I thought there was something going on down there at some point a while back, but whoever looked didn't find anything. The bike had 580+ miles on it when they replaced the bracket this week. The 60+ mile ride yesterday was incredibly smooth -- might have been the best it's ever been! (this could be any of a few things -- the bracket, the new, longer seat post, or the lack of DH, so I was riding at MY pace all day -- or all of those things!)

Thanks Deb! I'll keep an eye on this bracket!

the P.S. -- could it be that since the bike is under warranty, they chose to replace the part rather than leave a slightly damaged one in there?

Karen in Boise

[DebW]

the P.S. -- could it be that since the bike is under warranty, they chose to replace the part rather than leave a slightly damaged one in there?

Karen in Boise

Depending on the quality of the BB they installed, I'd guess the labor cost more and the shop won't recover that cost. I'd also doubt that the manufacturer would cover the BB after you rode with it loose (doesn't count as a manufacturing defect). So you should give those shop guys a big hug for doing this free under their own warranty. The old one could have been too damaged to work properly, or was at least damaged enough that it would never operate smoothly again.

[Geonz]

COokies work well, too...