Single-speed Conversion - Issue with alignment
05-19-20, 09:06 PM
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Single-speed Conversion - Issue with alignment
This is my first post on this forum so I apologize if I'm not giving enough detail or I'm posting in the wrong place. I've been tinkering with my commuter bike over the last few years but overall my technical knowledge is still fairly limited.
I've run into an issue after replacing a broken crank on my commuter bike where the chainring and cassette are not aligned, putting the chain under stress when peddling. I converted my commuter to single-speed a year or so ago by just removing the derailleurs and shortening the chain to a good gear ratio. I was lucky that things lined up nicely, but when my crank snapped I figured it was a good time to set the bike up as proper single-speed with a new crankset. I just installed a new 44T Retrospec Mantra Fixed-Gear/Single-Speed Crankset and as you can see from the attached pictures (had to attach them via PDF, the pictures wouldn't upload) they don't line up very well.
Worth noting is I bought a replacement used rear wheel recently from a local co-op for cheap as the old one was pretty rusted out. The axle barely fits in the frame so I'm not opposed to replacing it with a better suited wheel if that is the simplest approach. I tried the old wheel which I still have laying around and the gap is even bigger with it.
Any advice on how I could remedy this and get back to riding would be appreciated.
Cheers,
Chris
I've run into an issue after replacing a broken crank on my commuter bike where the chainring and cassette are not aligned, putting the chain under stress when peddling. I converted my commuter to single-speed a year or so ago by just removing the derailleurs and shortening the chain to a good gear ratio. I was lucky that things lined up nicely, but when my crank snapped I figured it was a good time to set the bike up as proper single-speed with a new crankset. I just installed a new 44T Retrospec Mantra Fixed-Gear/Single-Speed Crankset and as you can see from the attached pictures (had to attach them via PDF, the pictures wouldn't upload) they don't line up very well.
Worth noting is I bought a replacement used rear wheel recently from a local co-op for cheap as the old one was pretty rusted out. The axle barely fits in the frame so I'm not opposed to replacing it with a better suited wheel if that is the simplest approach. I tried the old wheel which I still have laying around and the gap is even bigger with it.
Any advice on how I could remedy this and get back to riding would be appreciated.
Cheers,
Chris
05-19-20, 09:33 PM
#2
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Did you change the bottom bracket? It probably requires a shorter spindle bb than you original had. I tried to find out what it should be, but retrospec doesn't list any specs. https://www.sheldonbrown.com/chainline.html is a good guide to chainline and should help you figure out how much shorter the bb spindle should be.
05-19-20, 09:50 PM
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Rear hub spacing is waaaaaay off.
https://www.mrrabbit.net/docs/freewhe...OLD_sizing.pdf
Has been posted here before....
Get the distance from the drive side locknut to end of hub freewheel threading down to 21 to 21.5mm.
=8-|
https://www.mrrabbit.net/docs/freewhe...OLD_sizing.pdf
Has been posted here before....
Get the distance from the drive side locknut to end of hub freewheel threading down to 21 to 21.5mm.
=8-|
__________________
5000+ wheels built since 1984...
Disclaimer:
1. I do not claim to be an expert in bicycle mechanics despite my experience.
2. I like anyone will comment in other areas.
3. I do not own the preexisting concepts of DISH and ERD.
4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
5. My all time favorite book is:
Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life
5000+ wheels built since 1984...
Disclaimer:
1. I do not claim to be an expert in bicycle mechanics despite my experience.
2. I like anyone will comment in other areas.
3. I do not own the preexisting concepts of DISH and ERD.
4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
5. My all time favorite book is:
Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life
05-19-20, 10:19 PM
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If you have a cassette on the rear wheel you should be able to move the cog you decided to use and the spacers to get a better chainline.
Cheers
Cheers
