Bottom Bracket Upgrade
02-06-23, 01:04 PM
#1
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Bottom Bracket Upgrade
I am restoring a 1984 Trek 560. The bottom bracket is standard English threaded, 68x119. The ends of spindle a have "male" threads protruding from the square taper. The whole bottom bracket is old and worn and I was hoping to replace it with a more modern cartridge style. However, the cartridge style BBs that I have found all have threads recessed into the end of the square taper. Would I be able to use one of these new cartridge style BBs and just find new hardware (I assume a small bolt) to mount my crankset? Or am I better of just keeping the old bottom bracket?
If I purchased a 73 mm would the spindle length be the same as the one that is currently on the bike? (119 mm)
If I purchased a 73 mm would the spindle length be the same as the one that is currently on the bike? (119 mm)
Last edited by Dominae; 02-07-23 at 10:49 AM.
02-06-23, 01:36 PM
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-----
the bottom bracket spindles with the male threads on the ends are known in the trade as "Type II" and also sometimes as "Maxy Type"
yes, you can mount your existing cranks on a spindle with recessed ends, not a problem
advantages of cartridges is that they are sealed, maintenance free and permit the fine tuning of chainline
at their introduction in the 1970's they were quite costly but have become a very good buy in today's market
-----
the bottom bracket spindles with the male threads on the ends are known in the trade as "Type II" and also sometimes as "Maxy Type"
yes, you can mount your existing cranks on a spindle with recessed ends, not a problem
advantages of cartridges is that they are sealed, maintenance free and permit the fine tuning of chainline
at their introduction in the 1970's they were quite costly but have become a very good buy in today's market
-----
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02-06-23, 01:48 PM
#3
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If going to a cartridge BB, check that the current spindle is asymmetrical or not. It could be longer on one side, usually the drive side. Most cartridge BB are symmetrical or really close to it. This may mean that you may need a longer spindle size in the cartridge BB to get the same position of the right crank. The left will then be out further.
02-06-23, 09:36 PM
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As @juvela notes above, using your present crank on a modern bolt-type bottom bracket is possible, in principle. You may need to carefully measure ale offset to match with a new bottom bracket, and be prepared to tweak or replace parts as needed to achieve proper chainline and mounting.
02-06-23, 10:56 PM
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If going to a cartridge BB, check that the current spindle is asymmetrical or not. It could be longer on one side, usually the drive side. Most cartridge BB are symmetrical or really close to it. This may mean that you may need a longer spindle size in the cartridge BB to get the same position of the right crank. The left will then be out further.
I also recommend you look for the UN-55 cartridge units. They were recently discontinued but a lot of bike shops still have stock of them. They're quite a lot better than the tourney level UN300 which replaced them, or generic chinese ones, at practically the same price.
And don't be too obsessive about getting exactly the same size spindle. Generally narrower is better until it won't work.
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02-07-23, 10:46 AM
#6
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The spindle on my bottom bracket is, in fact, asymmetrical. I didn't notice that when I removed it. Does the longer part of the spindle go on the drive side? I have seen the UN-55 cartridge bottom brackets for sale on line. Can you provide a little more detail how I would use a 73 mm instead of a (68 mm)? The spacers come standard with the bottom bracket?
If I purchased a 73 mm would the spindle length be the same as the one that is currently on the bike? (119 mm)
If I purchased a 73 mm would the spindle length be the same as the one that is currently on the bike? (119 mm)
Last edited by Dominae; 02-07-23 at 10:50 AM.
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02-07-23, 12:07 PM
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The spindle on my bottom bracket is, in fact, asymmetrical. I didn't notice that when I removed it. Does the longer part of the spindle go on the drive side? I have seen the UN-55 cartridge bottom brackets for sale on line. Can you provide a little more detail how I would use a 73 mm instead of a (68 mm)? The spacers come standard with the bottom bracket?
If I purchased a 73 mm would the spindle length be the same as the one that is currently on the bike? (119 mm)
If I purchased a 73 mm would the spindle length be the same as the one that is currently on the bike? (119 mm)
02-07-23, 03:53 PM
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To add to this, if your crank does require an asymmetric spindle, you can get a 73mm bottom bracket. Then you have 5mm of spacers to mimic that asymmetry.
I also recommend you look for the UN-55 cartridge units. They were recently discontinued but a lot of bike shops still have stock of them. They're quite a lot better than the tourney level UN300 which replaced them, or generic chinese ones, at practically the same price.
And don't be too obsessive about getting exactly the same size spindle. Generally narrower is better until it won't work.
I also recommend you look for the UN-55 cartridge units. They were recently discontinued but a lot of bike shops still have stock of them. They're quite a lot better than the tourney level UN300 which replaced them, or generic chinese ones, at practically the same price.
And don't be too obsessive about getting exactly the same size spindle. Generally narrower is better until it won't work.
Soody makes a good point that a slightly shorter spindle (as in one with no offset) usually works better in terms of pedal stance and chain line.
Until it doesn't that is.
Look for how much clearance exists between the current mounted chainring and the frame's chainstay. Only 2-3mm is needed there, but it's really needed.
If a chosen length of bottom bracket doesn't give sufficient chainring clearance, a "fixed cup spacer" can boost the spindle outward on the driveside unless the left side cup has a flange that bottoms out (though such a flange can be filed off if needed).
And be aware that front derailers only pull in so far, even with the lo-limit screw backed out. Too short of a spindle on the drive side just might cause hesitant shifting down to the small chainring.
I often take chances with this, just to get the shortest possible spindle to work. I have a pile of them (cartridge bottom brackets) to test with however, so most people might be a little more conservative than myself in terms of what they will want to order.
A 73mm bottom bracket sticks out by 2.5mm on each side, so allows one to position the bottom bracket laterally 2.5mm in either direction to adjust chainline. Spacers may or may not be needed, usually it's best to add a spacer on the driveside for the "cup" flange to bottom on, thus stabilizing the cup and allowing bottoming torque to keep it tight.
Most bottom brackets come with the necessary bolts, Shimano supplies nice 8mm socket head bolts with theirs.
Last edited by dddd; 02-07-23 at 04:35 PM.
02-07-23, 04:07 PM
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Measure from the cup to the taper end when installed. That is basically about what you need in clearance to make the chain line roughly the same. Problem is that you will have a bit more on the NDS. That’s where the suggestion for the LBS comes in handy. They might let you see some BBs and measure that.
My guess is you can probably get away with close to the same length as others have said unless the crank arm clearance on both sides is tight.
Be sure you know if it is JIS or ISO tapered.
My guess is you can probably get away with close to the same length as others have said unless the crank arm clearance on both sides is tight.
Be sure you know if it is JIS or ISO tapered.
Last edited by jdawginsc; 02-07-23 at 04:11 PM.
02-07-23, 05:01 PM
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Measure from the cup to the taper end when installed. That is basically about what you need in clearance to make the chain line roughly the same. Problem is that you will have a bit more on the NDS. That’s where the suggestion for the LBS comes in handy. They might let you see some BBs and measure that.
My guess is you can probably get away with close to the same length as others have said unless the crank arm clearance on both sides is tight.
Be sure you know if it is JIS or ISO tapered.
My guess is you can probably get away with close to the same length as others have said unless the crank arm clearance on both sides is tight.
Be sure you know if it is JIS or ISO tapered.
Measurement of the original cup/cone bottom bracket's driveside spindle extension will need to be done with bearings in place, and with the cup held squarely perpendicular to the spindle axis without any rocking of the cup.
02-07-23, 05:55 PM
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The only thing I have to add to all this is that when measuring and comparing the driveside spindle extensions of two different bottom brackets, the point of measurement should begin at the back or "inner" side of the driveside cup flange (where the flange will contact the frame's bottom bracket shell).
Measurement of the original cup/cone bottom bracket's driveside spindle extension will need to be done with bearings in place, and with the cup held squarely perpendicular to the spindle axis without any rocking of the cup.
Measurement of the original cup/cone bottom bracket's driveside spindle extension will need to be done with bearings in place, and with the cup held squarely perpendicular to the spindle axis without any rocking of the cup.
The bigger problem would then be the tapers which can funky it up.
As said above, more often than not the same length in cartridge brackets usually works fine since there is a bit of room for error and likely the difference in a mm for actual purposes.
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02-16-23, 07:11 AM
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https://www.bikeforums.net/newreply....ply&p=22792916
I was recently trying to replace a 1980 fuji touring bottom bracket with sealed cartridge and got a Shimano that had like measurements - 68 / 122.5 (my original spindle came at 122mm). It came with two chainrings by default. After disassembly I found the spindle indeed to be asymmetrical, and the chainline (didn't even know this phrase before this, first time ever doing this) to be visibly shifted leftward on the new, symmetrical Shimano. Besides this, left hand crank side fastening cup of the Shimano cartridge BB would not thread in no matter how delicately I tried to engage it with my BB, so I returned it. It stopped at about 1cm in and just would not take.
The spindle, quite nastily pitted (I think? silver, palpable damage and holes; grinds when play is removed) had 3SS stamped on it; looks like this
https://www.amazon.com/Sunlite-Botto.../dp/B000BMT32S
and the cups1.37"x24t as seen identically here https://www.bikeforums.net/classic-v...m-bracket.html - also seem to be sunline replacements for these on amazon, any opinion on these (sunline parts)?
per your suggestion, would this + a spacer work? Shimano Sealed Cartridge Square Taper Bottom Bracket BB BB-UN55 68 x 122 https://www.ebay.com/itm/385311447332
and any idea why the left fastening cup of the shimano cartrdige BB would not? The drive side went in OK and I couldn't see damage in my frame's BB threads; old cup goes in fine.
Sorry if this is hijacking your thread, I will remove if so. I was going to post about this with pics included but it seems answered here
To add to this, if your crank does require an asymmetric spindle, you can get a 73mm bottom bracket. Then you have 5mm of spacers to mimic that asymmetry.
I also recommend you look for the UN-55 cartridge units. They were recently discontinued but a lot of bike shops still have stock of them. They're quite a lot better than the tourney level UN300 which replaced them, or generic chinese ones, at practically the same price.
And don't be too obsessive about getting exactly the same size spindle. Generally narrower is better until it won't work.
I also recommend you look for the UN-55 cartridge units. They were recently discontinued but a lot of bike shops still have stock of them. They're quite a lot better than the tourney level UN300 which replaced them, or generic chinese ones, at practically the same price.
And don't be too obsessive about getting exactly the same size spindle. Generally narrower is better until it won't work.
The spindle, quite nastily pitted (I think? silver, palpable damage and holes; grinds when play is removed) had 3SS stamped on it; looks like this
https://www.amazon.com/Sunlite-Botto.../dp/B000BMT32S
and the cups1.37"x24t as seen identically here https://www.bikeforums.net/classic-v...m-bracket.html - also seem to be sunline replacements for these on amazon, any opinion on these (sunline parts)?
per your suggestion, would this + a spacer work? Shimano Sealed Cartridge Square Taper Bottom Bracket BB BB-UN55 68 x 122 https://www.ebay.com/itm/385311447332
and any idea why the left fastening cup of the shimano cartrdige BB would not? The drive side went in OK and I couldn't see damage in my frame's BB threads; old cup goes in fine.
Sorry if this is hijacking your thread, I will remove if so. I was going to post about this with pics included but it seems answered here
02-16-23, 07:15 AM
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https://www.bikeforums.net/newreply....ply&p=22792916
I was recently trying to replace a 1980 fuji touring bottom bracket with sealed cartridge and got a Shimano that had like measurements - 68 / 122.5 (my original spindle came at 122mm). The bike/spindle came with two chainrings by default. After disassembly I found the spindle indeed to be asymmetrical, and the chainline (didn't even know this phrase before this, first time ever doing this) to be visibly shifted leftward on the new, symmetrical Shimano. Besides this, left hand crank side fastening cup of the Shimano cartridge BB would not thread in no matter how delicately I tried to engage it with my BB, so I returned it. It stopped at about 1cm in and just would not take.
The spindle, quite nastily pitted (I think? silver, palpable damage and holes; grinds when play is removed) had 3SS stamped on it; looks like this
https://www.amazon.com/Sunlite-Botto.../dp/B000BMT32S
and the cups1.37"x24t as seen identically here https://www.bikeforums.net/classic-v...m-bracket.html - also seem to be sunline replacements for these on amazon, any opinion on these (sunline parts)?
per your suggestion, would this + a spacer work? Shimano Sealed Cartridge Square Taper Bottom Bracket BB BB-UN55 68 x 122 https://www.ebay.com/itm/385311447332
and any idea why the left fastening cup of the shimano cartrdige BB would not? The drive side went in OK and I couldn't see damage in my frame's BB threads; old cup goes in fine.
Sorry if this is hijacking your thread, I will remove if so. I was going to post about this with pics included but it seems answered here
To add to this, if your crank does require an asymmetric spindle, you can get a 73mm bottom bracket. Then you have 5mm of spacers to mimic that asymmetry.
I also recommend you look for the UN-55 cartridge units. They were recently discontinued but a lot of bike shops still have stock of them. They're quite a lot better than the tourney level UN300 which replaced them, or generic chinese ones, at practically the same price.
And don't be too obsessive about getting exactly the same size spindle. Generally narrower is better until it won't work.
I also recommend you look for the UN-55 cartridge units. They were recently discontinued but a lot of bike shops still have stock of them. They're quite a lot better than the tourney level UN300 which replaced them, or generic chinese ones, at practically the same price.
And don't be too obsessive about getting exactly the same size spindle. Generally narrower is better until it won't work.
The spindle, quite nastily pitted (I think? silver, palpable damage and holes; grinds when play is removed) had 3SS stamped on it; looks like this
https://www.amazon.com/Sunlite-Botto.../dp/B000BMT32S
and the cups1.37"x24t as seen identically here https://www.bikeforums.net/classic-v...m-bracket.html - also seem to be sunline replacements for these on amazon, any opinion on these (sunline parts)?
per your suggestion, would this + a spacer work? Shimano Sealed Cartridge Square Taper Bottom Bracket BB BB-UN55 68 x 122 https://www.ebay.com/itm/385311447332
and any idea why the left fastening cup of the shimano cartrdige BB would not? The drive side went in OK and I couldn't see damage in my frame's BB threads; old cup goes in fine.
Sorry if this is hijacking your thread, I will remove if so. I was going to post about this with pics included but it seems answered here
02-16-23, 08:14 AM
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left hand crank side fastening cup of the Shimano cartridge BB would not thread in no matter how delicately I tried to engage it with my BB, so I returned it. It stopped at about 1cm in and just would not take.
[…]
and any idea why the left fastening cup of the shimano cartrdige BB would not? The drive side went in OK and I couldn't see damage in my frame's BB threads; old cup goes in fine.
[…]
and any idea why the left fastening cup of the shimano cartrdige BB would not? The drive side went in OK and I couldn't see damage in my frame's BB threads; old cup goes in fine.
02-16-23, 06:21 PM
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Besides this, left hand crank side fastening cup of the Shimano cartridge BB would not thread in no matter how delicately I tried to engage it with my BB, so I returned it. It stopped at about 1cm in and just would not take.
any idea why the left fastening cup of the shimano cartrdige BB would not? The drive side went in OK and I couldn't see damage in my frame's BB threads; old cup goes in fine.
After disassembly I found the spindle indeed to be asymmetrical, and the chainline (didn't even know this phrase before this, first time ever doing this) to be visibly shifted leftward on the new, symmetrical Shimano.
per your suggestion, would this + a spacer work? Shimano Sealed Cartridge Square Taper Bottom Bracket BB BB-UN55 68 x 122 https://www.ebay.com/itm/385311447332
any idea why the left fastening cup of the shimano cartrdige BB would not? The drive side went in OK and I couldn't see damage in my frame's BB threads; old cup goes in fine.
After disassembly I found the spindle indeed to be asymmetrical, and the chainline (didn't even know this phrase before this, first time ever doing this) to be visibly shifted leftward on the new, symmetrical Shimano.
per your suggestion, would this + a spacer work? Shimano Sealed Cartridge Square Taper Bottom Bracket BB BB-UN55 68 x 122 https://www.ebay.com/itm/385311447332
You could make some chasing tools:
sun-etc parts are usually fine but it's just cheap chinese stuff and it's never gonna be smooth. I usually only bother with loose ball bbs with high end vintage ones in good condition, esoteric standards, or for bikes worth nothing.
The cartridge unit is better. That one is not what you want though. You want a 73mm one if you're gonna space it. That is a good idea imo.
