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1991 (I think) Trek 850 MTB bottom bracket replacement. Maybe similar to 830?

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I have a Trek 850 MTB that needs the bottom bracket replaced. Is there a standard size to order? If I take off the bike will there be a number that will help me order a new one or do I measure somehow? Thank you.

bottom-bracket

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edited 3 hours ago

Argenti Apparatus

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2

I have a Trek 850 MTB that needs the bottom bracket replaced. Is there a standard size to order? If I take off the bike will there be a number that will help me order a new one or do I measure somehow? Thank you.

bottom-bracket

share|improve this question

edited 3 hours ago

Argenti Apparatus

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asked 8 hours ago

Mark HMark H

1111 bronze badge

New contributor

Mark H is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

add a comment | 

I have a Trek 850 MTB that needs the bottom bracket replaced. Is there a standard size to order? If I take off the bike will there be a number that will help me order a new one or do I measure somehow? Thank you.

bottom-bracket

share|improve this question

edited 3 hours ago

Argenti Apparatus

42.2k33 gold badges4545 silver badges104104 bronze badges

asked 8 hours ago

Mark HMark H

1111 bronze badge

New contributor

Mark H is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this question

edited 3 hours ago

Argenti Apparatus

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asked 8 hours ago

Mark HMark H

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Mark H is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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share|improve this question

edited 3 hours ago

Argenti Apparatus

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Mark HMark H

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edited 3 hours ago

Argenti Apparatus

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edited 3 hours ago

Argenti Apparatus

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asked 8 hours ago

Mark HMark H

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asked 8 hours ago

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1 Answer
1

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4

Bicycle blue book says the 850 came with a BB-Lp26 bottom bracket, which was 68mm wide, 110mm spindle length, square taper. There are some new (old stock) on ebay, but I don't see why a newer BB-UN26 couldn't also be used (or any other standard ISO bottom bracket made for a 68mm wide shell, with a 110mm spindle).

I'd measure the BB shell and spindle width, just to make sure. Shell width is self-explanatory. You'll need to pull cranks to accurately measure the spindle width, and a caliper would be best. If you pull the BB, this info might be legible somewhere on the BB. I'd try pulling it before ordering a new one. Remember that the drive side has reverse thread, so clockwise to take it off. If it's from 1991, it may be seized pretty well. You may need to clamp a BB tool into a vise and use the entire bike frame as leverage to get it loose. I've had to do this in the past.

share|improve this answer

answered 8 hours ago

WPNoviceCoderWPNoviceCoder

45211 silver badge99 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thank you, will try and take it apart and see. Have tried some other rigid fork bikes and keep coming back to this one.
  
  – Mark H
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Shimano cartridge bearing bottom brackets---and the handful of other company's copy-cats I've seen--have the model number, shell width and spindle length printed on a sticker in the middle of the cartridge.
  
  – Jeff
  2 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Also note the offset of the spindle can vary, so the same length spindle may move the chainline a few mm.One option is buy a BB from a LBS that allows you to return it for an different length spindle (or get a shop to do it). A few mm chain line change will make no difference, if anything go a bit longer rather than shorted spindle to ensure the chain clears the frame.
  
  – mattnz
  2 hours ago
  

  
  
  
  

add a comment | 

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4

Bicycle blue book says the 850 came with a BB-Lp26 bottom bracket, which was 68mm wide, 110mm spindle length, square taper. There are some new (old stock) on ebay, but I don't see why a newer BB-UN26 couldn't also be used (or any other standard ISO bottom bracket made for a 68mm wide shell, with a 110mm spindle).

I'd measure the BB shell and spindle width, just to make sure. Shell width is self-explanatory. You'll need to pull cranks to accurately measure the spindle width, and a caliper would be best. If you pull the BB, this info might be legible somewhere on the BB. I'd try pulling it before ordering a new one. Remember that the drive side has reverse thread, so clockwise to take it off. If it's from 1991, it may be seized pretty well. You may need to clamp a BB tool into a vise and use the entire bike frame as leverage to get it loose. I've had to do this in the past.

share|improve this answer

answered 8 hours ago

WPNoviceCoderWPNoviceCoder

45211 silver badge99 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thank you, will try and take it apart and see. Have tried some other rigid fork bikes and keep coming back to this one.
  
  – Mark H
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Shimano cartridge bearing bottom brackets---and the handful of other company's copy-cats I've seen--have the model number, shell width and spindle length printed on a sticker in the middle of the cartridge.
  
  – Jeff
  2 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Also note the offset of the spindle can vary, so the same length spindle may move the chainline a few mm.One option is buy a BB from a LBS that allows you to return it for an different length spindle (or get a shop to do it). A few mm chain line change will make no difference, if anything go a bit longer rather than shorted spindle to ensure the chain clears the frame.
  
  – mattnz
  2 hours ago
  

  
  
  
  

add a comment | 

4

Bicycle blue book says the 850 came with a BB-Lp26 bottom bracket, which was 68mm wide, 110mm spindle length, square taper. There are some new (old stock) on ebay, but I don't see why a newer BB-UN26 couldn't also be used (or any other standard ISO bottom bracket made for a 68mm wide shell, with a 110mm spindle).

I'd measure the BB shell and spindle width, just to make sure. Shell width is self-explanatory. You'll need to pull cranks to accurately measure the spindle width, and a caliper would be best. If you pull the BB, this info might be legible somewhere on the BB. I'd try pulling it before ordering a new one. Remember that the drive side has reverse thread, so clockwise to take it off. If it's from 1991, it may be seized pretty well. You may need to clamp a BB tool into a vise and use the entire bike frame as leverage to get it loose. I've had to do this in the past.

share|improve this answer

answered 8 hours ago

WPNoviceCoderWPNoviceCoder

45211 silver badge99 bronze badges

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thank you, will try and take it apart and see. Have tried some other rigid fork bikes and keep coming back to this one.
  
  – Mark H
  6 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Shimano cartridge bearing bottom brackets---and the handful of other company's copy-cats I've seen--have the model number, shell width and spindle length printed on a sticker in the middle of the cartridge.
  
  – Jeff
  2 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Also note the offset of the spindle can vary, so the same length spindle may move the chainline a few mm.One option is buy a BB from a LBS that allows you to return it for an different length spindle (or get a shop to do it). A few mm chain line change will make no difference, if anything go a bit longer rather than shorted spindle to ensure the chain clears the frame.
  
  – mattnz
  2 hours ago
  

  
  
  
  

add a comment | 

Bicycle blue book says the 850 came with a BB-Lp26 bottom bracket, which was 68mm wide, 110mm spindle length, square taper. There are some new (old stock) on ebay, but I don't see why a newer BB-UN26 couldn't also be used (or any other standard ISO bottom bracket made for a 68mm wide shell, with a 110mm spindle).

I'd measure the BB shell and spindle width, just to make sure. Shell width is self-explanatory. You'll need to pull cranks to accurately measure the spindle width, and a caliper would be best. If you pull the BB, this info might be legible somewhere on the BB. I'd try pulling it before ordering a new one. Remember that the drive side has reverse thread, so clockwise to take it off. If it's from 1991, it may be seized pretty well. You may need to clamp a BB tool into a vise and use the entire bike frame as leverage to get it loose. I've had to do this in the past.

share|improve this answer

answered 8 hours ago

WPNoviceCoderWPNoviceCoder

45211 silver badge99 bronze badges

share|improve this answer

answered 8 hours ago

WPNoviceCoderWPNoviceCoder

45211 silver badge99 bronze badges

answered 8 hours ago

WPNoviceCoderWPNoviceCoder

45211 silver badge99 bronze badges

answered 8 hours ago

WPNoviceCoderWPNoviceCoder

45211 silver badge99 bronze badges