![]() |
verktyg Good to know, thanks for the reply! :)
I'm still trying to figure out spindle length I need to get.
Originally Posted by dddd
(Post 22293257)
Note that a threaded-together bottom bracket intended for 68mm will end up offset 1mm to the right in a 70mm shell. So you'll want to order a 2mm-shorter bottom bracket spindle length than what the crank is spec'd for.
|
Your only real concern is not getting one too short, so the inner ring interferes witrh the chainstay. A mm or two long will make no real difference.
|
Originally Posted by lagers
(Post 22293831)
verktyg Good to know, thanks for the reply! :)
I'm still trying to figure out spindle length I need to get. I'm still trying to wrap my head around this. If I understand correctly, for my FC-1050 crank (spec'd at 68x113 or 70x115), I'll need to order a 68x113 bottom bracket, instead of a 68x115 (or 116 since 115 is not available on eBay), due to the spindle being offset 1mm to the right? On a small number of frames, the left arm might possibly interfere with the left chainstay, but I've had that problem just once out of over 100 builds where I was trying for the shortest chainline (for the usual reasons of reduced chain angle and lowest Q-factor). The chainline issue would be less of a consideration for a rider who prefers to use primarily the small chainring, riding at in-town speeds. |
Alright, thanks for the explanation!
I'll order a 68x113 and see where it goes, I'll keep the thread updated. Thank you to everyone that has commented so far, it's been such a help! edit: I'll also post pictures when it's done, I'm looking forward to it |
That amazed me! Holy smokes, didn’t realize press fit went so far back!
https://cimg1.ibsrv.net/gimg/bikefor...13cf435d40.png |
A Silly Little Millimeter Longer
dddd et al....
Reference my post above: https://www.bikeforums.net/newreply....ply&p=22293819 1960's Cancer Stick Ads for 100mm and 101mm long carcinogenic devices: Somethings to consider... 3mm is less than 1/8"... Measure 3mm or 1/8" and then hold your fingers apart that much and look through the gap! I threw this Flickr Album together one night 10 years ago when I was building a SS wet weather beater. I was looking for a BB combo using parts that I had on hand. Read my notes below the photos. https://www.flickr.com/photos/282672...57627678462359 Bottom line: IF IT FITS - IT WORKS! When crank arms are removed and reinstalled or when they are re-torqued, the aluminum deforms and the arms move further up the BB spindle/axle each time. When installing used arms, there's no telling what their history is. Before mounting them, I slip them onto the spindle to see how far they go on or if they will work at all. https://cimg4.ibsrv.net/gimg/bikefor...ecb63f1f0f.jpg Next I thread in a fixed cup and using caged 1/4" ball bearings I put the spindle into the BB and then slide the drive side crankarm on till it stops. That will give me an idea of how close the inner chainring comes to the chain stay. Bear in mind that when tightened the crankarm will fit on 2mm to 3mm closer. One of the caveats about buying used cranksets is what condition are the squares in. :foo: If they have been wallowed out from running loose or have stretched too far from frequent re-tightening you have a problem. A simple fix that sometimes works when the cranks fit too far on the spindle is to put a second washer under the crank bolt to take up some space. File or grind the opening of the washer so that it will pass over the end of the spindle. NEXT: Chain Line.... Precise Chain Line was/is an obsessional British affectation when using stiff 1/8" chains on Fixed, Single Speed or Internal Gear Hubs. With the advent of flexible 3/32" chains in the late 70's chainline is not that much of in issue if it's close enough - if you can easily shift on and off of all of the rear sprockets. One concern is when the chain is on the small chain ring, making sure that it doesn't rub or drag on the inside of the big ring when you are using the smallest rear sprockets. It's more of an issue with triples. Common sense and tradition says don't use Big-Big and Small-Small chainring - rear sprocket combos. Consider 9,10,11 and 12 tooth cassettes and how much a chain has to deflect to cover the full width. BTW, how wide are the 10, 11 and 12 speed cassettes. After 15 minutes of searching was how wide the chains were??? verktyg :50: |
Originally Posted by Yelbom15
(Post 22295033)
That amazed me! Holy smokes, didn’t realize press fit went so far back!
https://cimg1.ibsrv.net/gimg/bikefor...13cf435d40.png |
I should have mentioned that I am quite fussy with regard to chainline.
I live in the foothills, and prefer to be able to smoothly use the full range of rear cogs while staying on the big ring as much as possible, so my bias is always for a shortest-possible chainline! The issue became more of an issue when compact cranks (with their 16t gearing gap) arrived, and the issue is also more of an issue when using DT shift levers. As I said though, for more of an in-town ride, a longer chainline is less of an issue since the rider will be dropping to the small ring often or may stay there. Also, some gruppos designed around possible oversized seat tubes and/or triple cranks really have on over-generous chainline, because the component group was firstly designed to work with all the worst-case situations of achieving a robust shift to the small ring. But for bikes with 26.8mm standard steel seat tubes, the chainline usually tends to be greater than it should and needs to be for robust (front) downshifting and smoothest chain movement. |
Originally Posted by lagers
(Post 22292476)
I recently purchased a second-hand 'new' Panasonic frame to replace my current one. It's a steel Panasonic 'livespot' frame. To my surprise, it didn't have any threads in the BB shell. I went to 3 local bike shops and they all told me they couldn't cut any threads so I'm not sure what my options are.
Depending on the inside diameter measurement, it may be possible for it to be threaded, or perhaps even install a threaded sleeve: https://www.framebuilding.com/NEWPAR...MAGES/bb30.jpg https://www.framebuilding.com/NEWPAR...B%20shells.htm |
| All times are GMT -6. The time now is 11:34 PM. |
Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.