Here's the difference between road hubs and mountain hubs.
As I related in my updates on my LHT page, I wanted to convert a road hub to mountain bike hub spacing. So what follows are a few notes about the process.
First; My reason for needing to perform this modification is purely aesthetic.Today's mountain hubs are chunky, black ugly things. Unfortunately, road hubs are starting to look that way too. I wanted to use the older style 105 hubs, but they aren't available and the current model looks fat, like a Mountain hub. At least it's not black. But since I had to go with that look anyway, I decided to go one level down and get a Tiagra hub for about half the cost. For the axle and spacer, I cannibalized the parts from a broken lower-end Shimano MTB hub.
First; My reason for needing to perform this modification is purely aesthetic.Today's mountain hubs are chunky, black ugly things. Unfortunately, road hubs are starting to look that way too. I wanted to use the older style 105 hubs, but they aren't available and the current model looks fat, like a Mountain hub. At least it's not black. But since I had to go with that look anyway, I decided to go one level down and get a Tiagra hub for about half the cost. For the axle and spacer, I cannibalized the parts from a broken lower-end Shimano MTB hub.
Tiagra hub is below the old mountain hub.
Converting the Tiagra Road hub simply entails expanding the locknut-to-locknut spacing from 130mm to 135mm. You need a longer axle and 5mm of spacers. Fortunately, the old MTB hub's axle was in fine condition. It was straight and the threads were in good shape. So I figured I could use that. It also had a spacer which would work out fine for my purposes.
So, first step is to remove the axle from the old and the new hubs.No problems here, just loosen the locknut off the left (non-drive side) then pull it out of the hub. Be careful not to drop any of the loose bearings. The cups and locknuts of the Tiagra fit the old hub's axle fine. (I naturally wanted to use these as they were virtually pristine.) Below is a shot of the two axles:
The original axle and the longer MTB axle.
Now it's simply a matter of assembling the Tiagra's cones and spacers on the old axle, then inserting them into the Tiagra hub. But remember you have to add 5mm of additional spacer on the non-drive,(left) side in order to properly center the flanges and take full advantage of the wider spacing.
Putting the pieces back together.
This is a good time to glop some extra grease onto the bearings as well, although I am happy to report that the Tiagra's bearings were well lubed from the factory, but you can never have enough grease on those guys!
That's
pretty much it. I then laced us the hubs to some polished Sun CR-18's
and installed them on my LHT. These are so much more quiet than the
Nashbar hub.
Now that I have removed the axle from the mtn hub, I decided to strip off anything else that might be useful. Well, there's not much actually, but I might have need of the cassette body someday so I took that off. This is the first time I've removed one of these from a Shimano hub. Turns out to be quite easy: With the axle removed, take an 8mm Allen wrench and tug hard. The threads are conventional; righty tighty, lefty loosey.
Removing the Freehub mechanism.
You're unscrewing this large hollow bolt which holds the cassette body in place. After you've loosened it, (it'll be on pretty tight), you just pull it out:
With the bolt removed, the cassette pulls off easily.
Off it comes!
I'll hold onto this, it's a steel body which is supposed to be a little sturdier than alloy bodies, albeit somewhat heavier.
