2006 Trek 4900 & E-Type Bottom Bracket Question
#1
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2006 Trek 4900 & E-Type Bottom Bracket Question
So I'v had this little 13" 2006 Trek 4900 sitting around my garage for a few years and I felt like putting it back together. The only issue is I somehow misplaced my bottom bracket.
I believe it was a 73x110 E-Type Square taper (as the bike can only use an E-Type front derailleur).
I can't find one of these for sale...
Can I use a regular old cheap bottom bracket such as the Shimano UN53? Obviously it'll fit the frame, but will I run into any issue with chain line? I'm worried about having the chainrings too far from the BB shell.
Trek 4900
Shimano UN53
I believe it was a 73x110 E-Type Square taper (as the bike can only use an E-Type front derailleur).
I can't find one of these for sale...
Can I use a regular old cheap bottom bracket such as the Shimano UN53? Obviously it'll fit the frame, but will I run into any issue with chain line? I'm worried about having the chainrings too far from the BB shell.
Trek 4900
Shimano UN53
#2
Senior Member
Based on what I've read, there are special square taper bottom brackets that offer the correct chainline when used with E-type deraillers. I can't seem to find any for sale either though. It may be simpler in the end to buy an integrated spindle, external bearing crankset, all of which as far as I know can accommodate an E-type derailler (you simply don't install one spacer).
Here's an option for under $100 inlcuding BB: https://www.universalcycles.com/shopp...5&category=380
Here's an option for under $100 inlcuding BB: https://www.universalcycles.com/shopp...5&category=380
#3
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Ugh not what I wanted to hear. I guess il have to search my garage some more.
#4
Senior Member
This has me really curious. Unfortunately, my curiosity has not paid off with any more of a lead than this: https://www.bikeforums.net/showthread...ottom-Brackets
Seems to be an active member and maybe he still has some. Worth a shot. I may buy one too just to have since they are apparently quite rare these days!
Seems to be an active member and maybe he still has some. Worth a shot. I may buy one too just to have since they are apparently quite rare these days!