I live in the US (NJ). I’ve been using Zwift for several years with a CompuTrainer platform and a ‘vintage’ Puch road bike with 2x6 gears. The setup works fine and I spend about half my time in ERG mode.
The new Zwift Hub One looks like a nice upgrade for me, e.g. no more reaching down to manually switch gears, more gears, no more worrying about tire pressure, and no calibration period (6-7 minutes).
I’m not very knowledgeable about bicycle mechanics, but from what I can tell, I can’t use my 6-speed because the rear fork isn’t wide enough, thus if I want to use the Hub One, I need to also upgrade my bike.
I’m looking for suggestions on either modifying my current bike (if possible), buying a new/used bike or even building something from parts. I don’t ride outside so this bike only needs to work with the Hub One. Since I’d be spending $449 for the Hub One, ($599-$150 subscription), price on the upgrade is definitely a consideration.
Similar question was recently asked. In your case a 6 speed frame is probably only 4mm narrower than the Zwift Hub’s axle spacing so you may be able to just jam the bike on the trainer with a bit of effort flexing the chainstays apart. You could also ask a bike shop to respace the frame properly. You could probably get a price for that over the phone.
Thank you for responding Paul. So all I need to do is to widen the frame/chainstay where it would attach to the trainer? The current chainrings and derailleur would work fine?
With the Hub One, you should not need to worry about the derailleur or chainrings. If I were doing what you are planning, I would clean them and put a new chain on it. If you care about the frame and it’s steel then I would bend the chainstays and align the rear dropouts. Even if you don’t do that last step then it will probably still work OK if you apply some force to get it on the trainer. You might need an extra pair of hands to get it on.
4mm isn’t a lot, but if you aren’t sure how to bend the frame, take it to a shop. No shame in letting the pros do it Some things to consider:
-If it’s aluminum (or aluminium if you’re British), bending can go badly. Steel should be able to accommodate easily. Alu not so much–you could damage the frame.
-Just pulling it apart and jamming it into place could damage the trainer’s hub. You’ll be putting extra strain on the bearings that’s not normally there. Again, 4mm isn’t a lot, but the bearings and hub weren’t designed to take those forces pressing in/at an angle.
-If it’s steel, you can ‘cold set’ the frame…basically permanently bending/widening the rear triangle. That will avoid those stresses on the hub.
-If you’ve never done that before…I would take it to a shop. Not only do you need to get the frame bent far enough, but as Paul mentions, you need to make sure the dropouts are aligned. (The slots that the skewer and axle fit into.) If those aren’t pointing straight towards each other, your bike will be crooked on the trainer. A shop will be able not only to cold set the frame, but they’ll have specific tools for aligning the dropouts.
This is stuff that can be done at home if you’re handy enough. But can also go poorly if you’re not But it’s doable stuff (with a steel bike).
Oh yeah, that’s some good stuff! The nice thing about it is if you’re going that incremental sort of route, it’s hard to mess it up to the point that your LBS can’t fix it again if you go too far, because you’re not cranking on it super hard. That Sheldon Brown link uses a 2x4. That can work, but you gotta know your own strength, lol.
Some things to consider:
some good stuff! 
The nice thing about it is if you’re going that incremental sort of route, it’s hard to mess it up to the point that your LBS can’t fix it again if you go too far, because you’re not cranking on it super hard. That Sheldon Brown link uses a 2x4. That can work, but you gotta know your own strength, lol.