30. How to Overhaul A Bottom Bracket
How to disassemble, re-grease, reassemble and adjust a cup and cone bottom bracket.
Today we’ll learn how to overhaul and re-grease an adjustable bottom bracket. To remove the cranks you’ll need a crank puller, a 17mm open end wrench and a large adjustable wrench. To overhaul the bottom bracket you’ll need a bottom bracket wrench or a pin spanner, a hooked lock ring wrench, and a 36mm wrench. For re-greasing the bearings you’ll need some cleaning solvent and waterproof grease, a rag, a toothbrush and a small container to clean the bearing cages.
Begin by removing the cranks. Watch the cotterless crank removal tutorial for a more detailed procedure. Once the cranks are removed, loosen and remove the lock ring on the non-drive or left side of the bike by turning counter-clockwise. Once the lockring is removed you should be able to easily loosen and un-thread the bearing race using either a pin spanner or a bottom bracket wrench.
Now pull the spindle and both bearing cages out of the frame. It’s important to remember which way the spindle came out, as they are directional. The drive side usually has a longer distance from the bearing race to the end of the threads. Wipe off the bearing cages, drop them into the solvent, and let them soak while you use your rag to clean the spindle and both outer bearing races.
Tighten the drive-side bearing race by turning it counter-clockwise with your 36mm wrench. Unless you are replacing the bottom bracket, there is no need to remove it.
Shine a flashlight into your bottom bracket shell to inspect the bearing race for pitting and wear. Inspect your other bearing race and then carefully inspect the spindle. Most wear occurs on the spindle’s bearing races. If you see pitting here you should take it to your local bike shop for a replacement.
Now clean both bearing cages with a toothbrush and solvent, and then set them aside to air-dry. These should also be replaced if they are worn or have bent cages.
Apply a layer of grease on both bearing races and cages. A grease gun makes it easy to squirt grease inside the gaps between the bearings. Then place the bearing cages into both races. The rounded side of the cage should be facing down into the bearing race. Seal them in with another layer of grease.
Now insert the spindle the same way you removed it. Wipe off any excess grease that comes out on the spindle. Grease the threads inside the bottom bracket shell, and then slide the outer race and bearing cage onto the spindle. Thread it on all the way clockwise but don’t tighten it. Again you’ll need to wipe off excess grease.
Thread on the lock ring finger-tight. Before adjusting the bottom bracket, first install the drive-side crank arm and tighten it as shown in the crank installation tutorial. This will help us make a proper adjustment. Now hold the inner race firmly with your wrench or spanner and tighten the lock ring. When properly adjusted the spindle should spin smoothly. If it doesn’t, you’ll have to loosen the lock ring, back off the inner race a little bit, and then tighten it again.
Check for play by placing the crank arm close the frame and pushing and pulling it against the frame. There should be no movement. If it feels loose, you’ll have to loosen the lock ring, tighten the inner race a little bit, and then tighten the lock ring again. When the adjustment is correct, install and tighten the left crank arm and you’re done!
I've had a Raleigh Silver Jubilee since it was new in 1977. The chainset needs replacing. I have not been able to find a replacement that gives anything like the correct chain line. Can anyone help?
The alternative would be a shorter spindle. The original was a 126mm 5s. I can't find anything shorter to fit the 70mm frame. It probably needs to be about 116 mm. Help?
If a shorter spindle is not available I could replace the existing bearings with a cartridge but I can't find anything 26tpi for a 70mm shell. What would you suggest?... Read more >>
Looking to rebuild the entire drive train on an old frame. To start, I'm looking at the Shimano Tourney A070 double crank set. But I can't make head or tails of the spec sheet I've found for a compatible BB? Shimano's recommendation is the BB-UN26, for which there are at least 5 different lengths (from what I can tell from some ... Read more >>
Hey folks! First post. I'm working on a salvage project, re-building a road bike from an old frame. I want to put a cartridge BB in it, but I need some help figuring out sizing, etc. Disclaimer: I'm terrible with brands, but good with the mechanical side of things; you may have to hold my hand a little through this one.
I've looked at some of the stuff from Sheldon Brown, but it's really going over my head. Or maybe my mind is just saturated... I've been doing a lot of reading...
Anyway, the old spindle was a 3T, which I believe means I'd be best suited picking up a 1... Read more >>
I've got an old bike that I've decided to finally give some TLC - can't bear to part with it. It's a year 2000 Giant ATX 830 mountain bike.
Not my bike, but this is what it looks like:
Giant ATX 830
It sports a 68mm, English thread BB, and a 3x8 Diamond taper crankset. I've measured my chainline to be approximately 49mm - 50mm, from the centre of the frame to the centre of the middle cog on my crankset.
... Read more >>
Replaced my bottom bracket a couple month's ago from a english style to a sealed cartridge. My problem is that it keeps loosening up. The inside tightening nut, next to the chainrings, is the one that is coming loose. I have tightened the mess out of it at least 3 times now and it has loosened up again. Makes a sqeak on the down stroke. My bike has the front derailleur that is held by the inside tightening nut of the bottom bracket.
I followed the directions and put grease on the threads of the bottom bracket and assembled it and tightened, but still it come... Read more >>
I'm new here, but thought I would share my recent experience trying to repair a crack in my Merlin Taiga frame. The crack originated in the weld between the BB and the seat tube during a cycle tour in southern Chile. Two attempts at welding were unsuccessful and it was suggested by several shops that I junk the frame. Having $800+ invested in S&S couplers plus many thousands of miles of love and companionship, I couldn't do it, so I set out to find a repair on my own. My dad is a machinist and we contemplated a mechanical fix - some sort of brace or clamp, bu... Read more >>
I have a 1994 GT that I have added many upgrades to. I would like to get rid of the old FC-TY21 crank set. I really like the hollow tech parts like Deore or DLX. Can I swap this stuff in? Spindle length on the original parts is supposed to be 122.5 mm per http://www.shimano.com/publish/content/global_cycle/en/us/index/tech_support/tech_tips.download.-Par50rparsys-0... Read more >>
I am custom building my own bike, basically I am building a bike from scratch. I've got the frame and I have measured the shell width which is 68mm. I have bought a single speed 44 Tooth chainset/crankset. Now how do I know which size bottom bracket would fit the crankset? Would I have to buy 3 or 4 different size bottom brackets and try each one out to get the right bottom bracket? Somebody please help.
Ibs... Read more >>
i believe i need to change my BB, when i pedal on a hill or pedal with power i hear a creaking sound. ive checked my handle bars, pedals as recomended in another thread.
does any one know a suitable replacement BB?
i also want to replace 1 ring( the biggest one) on the chain ring.. should i ? or should i just replace the whole crank set?
i would like to have a bigger gear when i put the fD to "3"
would i need to replace my chain as well?
can any one tell me about this bike. i havent found much about it ... Read more >>
Hi Guys, first post here. I've been using the site to help me maintain my bikes for a few years now.
I'm visiting the US for a bit and picked up a bike on craigslist (a huffy road bike early 80s I think), only cheap but on a short test cycle it felt solid. I did notice the crank had a bit of a wobble. Anyway I bought it and figured I'd put it into the LBS to overhaul the BB, new bearings and grease, etc.
Picked the bike up from LBS and had a ride, the crank is solid now (no play), but I think maybe they over tightened it or messed up the bearings as I'm now getting t... Read more >>
[attachment=4264]Hi this is my first post, but I have been lurking for a while and have searched but not found any similar posts. I have been using my 1992 Nishiki Backroads MTB as a daily commuter. I noticed some grinding from the bottom bracket and figured I could make it to the weekend to address it. As I was riding the crank bearing failed. I took it to an LBS and they had it two weeks, the shop owner stating he has not been able to get the bearing race from the bottom bracket on the ring gear side. I brought it home as I need to get back on the road. Any suggestions?
Thanks.... Read more >>
About 2 weeks ago I overhauled the bottom bracket on my 1970s era Schwinn Traveler III. It obviously has a cup and cone bracket and takes 1/4 inch herrings. The bike rides smooth as silk, but when I was sweeping my floor yesterday I found a bearing and realized that I must have only 10 bearings on one side of the bottom bracket, and 11 on the other. Since the bike is riding so well, do I still need to overhaul it again and add in the missing bearing? I'm not all that stoked about getting grease all over my hands if I can help it.
Nik... Read more >>
So I had a fall the other week, and my bottom bracket isn't properly orientated any more (See picture), I was thinking that the force of the impact caused the issue and maybe it just requires another short sharp shock to orientate i again, I have given it a firm push to try and correct it, but I really want a second opinion before I start deliberately bashing my bike.
Any help would be greatly appreciated.
[attachment=4215]... Read more >>
Hi, After about 5 months my first bottom bracket packed in, it was a shimano one (cant remember the model). I replaced it with a wheels manufacturing BB which lasted about a year. I then had a bike shop replace that one in about march. It honestly lasted about 3 weeks. So I replaced it with a Shimano 7900 Dura-Ace towards the end of April and now its about to go (the usual noise from a bb thats on its last legt). I can get rid of the noise temporarily with cleaning and some grease but it will come back within a few miles. My question is, is there anything that would cause the BB to pack in so ... Read more >>
It's probably been asked before but is there a replacement bottom bracket to update this spindle to one with a JIS taper? The bike appears to be of French manufacture... Peugot? I'm thinking of the Shimano UN-55 / UN-26 BB but need one that will fit the French treads. The goal is to replace the crankset.... Read more >>