Rear dropout conversion - new wheel?

[suffolksky]

Hi there,
I'm converting the rear dropout on my dawes galaxy from 120mm to 130mm to support a tiagra groupset with a 9 speed cassette. I think I need a new wheel to do this, but i'm not quite sure what I should be looking for on eBay. Any advice on the specifications? (also if anyone has any general advice about this conversion e.g. cold setting, that would be a welcome bonus!)

 

[cromoman]

Re:

There are plenty of resources out there telling you how to do the cold setting (bending!).

Search Youtube for RJ The Bike Guy. He demonstrates how to do it with a threaded rod, and in another video shows you how to make your own dropout alignment tools, which are essential for this job.

https://www.youtube.com/watch?v=YdibmxBuMy0

https://www.youtube.com/watch?v=PsU8IkkFaok

Sheldon Brown explains how to do the plank of wood method https://www.sheldonbrown.com/frame-spacing.html, and also how to check the alignment of the frame afterwards.

The big problem that you might encounter when doing this is on a 120mm 5-speed setup there is a big gap between the smallest cog and the dropout. With 9-speed there isn't. You may find that on a re-spaced frame, the chain fouls the bottom of the seat stay when in the smallest sprocket, or when changing out of the smallest sprocket into the second smallest. You can counter this to an extent by moving the wheel forwards in the dropouts, or by selecting a cassette with an 11 tooth sprocket, but you might end up not getting the ratios you want.

That said, it might just work perfectly!

 

[pigman]

Re:

any rear wheel with a shimano/sram 8/9/10 speed freehub will do you.
if its a 10 speed hub, you may need to buy a spacer

edit : if they are built with MTB hubs, they are 135mm wide, so stick with road

 

[suffolksky]

Re: Re:

There are plenty of resources out there telling you how to do the cold setting (bending!).

Search Youtube for RJ The Bike Guy. He demonstrates how to do it with a threaded rod, and in another video shows you how to make your own dropout alignment tools, which are essential for this job.

https://www.youtube.com/watch?v=YdibmxBuMy0

https://www.youtube.com/watch?v=PsU8IkkFaok

Sheldon Brown explains how to do the plank of wood method https://www.sheldonbrown.com/frame-spacing.html, and also how to check the alignment of the frame afterwards.

The big problem that you might encounter when doing this is on a 120mm 5-speed setup there is a big gap between the smallest cog and the dropout. With 9-speed there isn't. You may find that on a re-spaced frame, the chain fouls the bottom of the seat stay when in the smallest sprocket, or when changing out of the smallest sprocket into the second smallest. You can counter this to an extent by moving the wheel forwards in the dropouts, or by selecting a cassette with an 11 tooth sprocket, but you might end up not getting the ratios you want.

That said, it might just work perfectly!

Thanks! The RJ videos are fantastic.
That's interesting about the cog spacing. Any idea if there would be the same problem if i converted to 3x8 speed instead?

 

[suffolksky]

Re: Re:

any rear wheel with a shimano/sram 8/9/10 speed freehub will do you.
if its a 10 speed hub, you may need to buy a spacer

edit : if they are built with MTB hubs, they are 135mm wide, so stick with road

very helpful, thanks!

 

[suffolksky]

I'm also unsure about the crank/bottom bracket conversion. I've found a tiagra gear set that i'm happy with and it comes with a matching bottom bracket. Will the bottom bracket fit my frame? If they're not universal, how can i tell which will?

 

[mattr]

If its a dawes galaxy it'll almost certainly be a standard 68mm british threaded. Which the standard tiagra bottom bracket will fit.

 

[suffolksky]

Re:

Okay that's good. But lastly, is there any mechanical reason to change the crank set? I think i want a new one, but I'm guessing the rest of the conversion would actually work without changing it?
Thanks for all your help again

 

[mdvineng]

Why not go for 126mm rear and a 7 x 3 setup, much less bother and danger of mishap with plenty of ratio's

 

[ScillySuffolk]

Re: Re:

Search Youtube for RJ The Bike Guy. He demonstrates how to do it with a threaded rod

I've always advised against using the threaded rod method, so I was interested to see him get it right, first time.

My reasoning being that one side is being braced against the other and the inevitable small differences in materials and construction, mean one side will be stiffer/stronger than the other.

So as you expand the rear triangle, one side will move more than the other (if at all) and you'll screw the alignment up.