Bolt-on cog/hub + flip/flop?

Hello all.

I have a GT 29er SS that I sees a moderate amount of off-road use, but I'd like to use as a fixed beater/pub-bike as well. It has disc brakes front + back and an eccentric BB with vertical dropouts.

The front wheel needs replacing (taco'd the rim when I was last oout on the trail), so I thought I would plump for a whole new wheelset - and thought that a Velosolo-converted Shimano M756 would probably be the ticket - run it fixed on the road, then remove the cog and replace with a disc rotor ( and possibly 1-2 spacers in order to line-up the rotor properly) and stick a cog on the freewheel in order to run offroad SS?

Has anyone ever done or seen anything like this? As far as I can see, the main problem will be in dishing/chainline/disc-rotor-alignment, but I guess that there's scope to space out either disc-rotor or fixed cog, if necessary. Is this a ridonkulous idea, or feasible?

Interesting idea. Better to have two frames though. It'll be annoying having to set them up otherwise.

or two wheels.

Sounds like a real ball ache to change, and if you want to do it frequently may drive you up the wall.
Why not just ride freewheel on the road with two discs?

thinking about it surely tyres are going to be the biggest problem. What you want on road and what you want off road don't usually match up, same with gear ratio as well.

^+1

I use the same tyres and gearing on road and off but have to admit it is compromised!

I run a 62 GI with 35c Ribmo's. The gearing is okay on road by can be hard work on off road climbs or technical terrain. The tyres are fine as long as there is low mud count, which there is where I live.

35c on a 29er is very thin isn't it?
a 2" 29er tyre is around 51c, and most 29er tyres I have seen are 2.2s. So thats about 58c (ish). Thats really way big for on road if that is what the dude is going to be using.

But I do conceed on 35s its not the end of the world :)

But I am running 35c on a 700c road rim rather than a 700c 29er rim and the tyres are pushing the limit width wise.
I find narrow tyres off road to be fine and are very fast, clearly more cyclocrss than 29er.

You need to keep on your toes going round fast corners though...

Realistically, my bike (and I) only really make it out on to the trail every other month. I can't justify having a fourth bike (in addition to fixed commuter, geared racer and the 29er). I guess a wheelset for pub use (with appropriate tyres - just placed an order for Schwalbe Big Apple 2.35" tyres). I'm going to give the Velosolo-converted Shimano hub a go and still keep the mediocre stock machine-built wheel that came with the bike. I'll have a go at flip-flop - as far as I can see the main problem is going to be replacing the cog with a disc rotor and changing the tyres before going on the trail, which is probably about 20-30 mins work. If I get bored of 40-60 mins (convert to trail and back to road) work every time I want to flip between fixed and SS, then I'll settle for having separate wheelsets for on- and off- road use.

Will post pics and progress as and when ...

Sounds like a nice set-up. Bit of work to get the bike trail ready. Because of were I ride, I like 165mm cranks for fixed road riding (spinning down long hills), and 175mm cranks for singlespeed off roading (for leverage up hills). So would'nt work for me. Lots of people like to run the same cranklength regardless of use though.

V-brake on the back?

• something like this
  http://www.chainreactioncycles.com/Models.aspx?PartnerID=79&ModelID=33699