Rear Wheel Switch - Freehub to Cassette?

[Berti]

I have an old Fuji Absolute road bike that I wish to convert to single speed. The rear wheel (27in) has a freewheel hub. I know that attempting to just screw on a single speed freewheel on to the hub after the gears are removed can lead to chain-line issues, and that single speed conversions on old wheels with cassette hubs can often be done successfully with cassette spacers and and an appropriate cog... If I just find an old 27 inch road bike wheel with a cassette style hub would there be any issues just doing a conversion on that wheel and using it on my bike? What problems might I run in to?
p.s.
...site is so helpful, I am very grateful to not have to deal with pretentious Chicago hipster bike mechanics to do things that really are simple with some effort...thanks. =)

[AlanK]

Maybe you could upgrade to a 700 size rim, there could be enough room for adjustments on the brakes. It really does depend on what the actual size of the rim is on the bike now. I had a bike mechanic show me that a rim I had on an old Bianchi was capable of taking a 700 sized tire. But he understood tire sizes better then I did so he knew it would fit, I didn't
Read this article and perhaps measure what you have to see if a new rim is compatible with your bike.
http://sheldonbrown.com/rim-sizing.html

[AlanK]

Hey wait a second look at this one
http://sheldonbrown.com/harris/singlespeed.html#sprockets

[Alex Ramon]

If you find a cassette hub it should work ok. Just make sure the rear sprocket is centered on the <a href="http://bikeride.com/freehub-body/">freehub body</a>, using spacers on either side until it sits in the middle. That should give you a good chainline. Here are some single speed kits that might help.

[ironbirdexplorer]

Being a relatively new guy to mountain biking (I've always ridden mountain bikes the way yuppies drive SUV's!) and having done a fair bit of cross country and riding in the bush away from civilization (and repair shops) this past summer, I have a question that sort of relates to this topic.
This summer (on my second last day of holidays so there wasn't much worry...), I took a fairly big stick through my back wheel and rear derailleur. It bent my rear derailleur (a Shimano ACERA) such that it interfered with my spokes when I shifted below 3rd gear. Not being very mechanically inclined, I figured just bending it back into position would suffice. It did...until the next day when I went to use it again...the rear derailleur snapped off.
I was at camp, and not way out in the bush, so no worries, but here's my question. If I were out in the bush and this happened, would I have been able to remove the derailleur, shorten the chain, and turn the bike into a 3 speed or even 1 speed (using the front three chainrings) in order to limp home?
Thanks
Ironbirdexplorer

[DaveM]

You would be able to make it a 1 speed. You couldn't get three because you still would need the chain tensioning of the rear derailleur to be able to shift at the front.
The trikiest part of this is finding a combination of front and rear gears that will give you decent tension on the chain. Without the derailleur, then chain needs to be fairly tight to keep from popping off from any small bump. Most moutain bikes do not have drop out (where the rear wheel bolts into the frame) that allow you to adjust the wheel forward and back to adjust tension. But on most bikes, you can find a gear combination that will allow for a reasonably useful gear and adequate chain tension.
FYI, this is also the quick & easy what to convert your bike to a single speed if you want to try that out.

[ironbirdexplorer]

Thanks for the response Dave. My next question would be, if I was in that same scenario, which one of the front three chainrings would I aim to shorten and match the chain to? My guess, since this would constitute the end of the ride (at least for me) and a beeline for the car / home / basecamp, etc, try and keep it in the lowest possible gear? Or would I keep it on the middle chainring / middle sprocket?
Thanks
Ironbirdexplorer

[DaveM]

Middle chainring is usually your best all around gear unless you know you have some real steep uphills or downhills coming up

[twowheels4ever]

As DaveM said, you could do this, but there is one slight problem (which I've seen). DO NOT shift up! The tension on the chain, rear hub, and derailleur will put a strain on the cassette and may stop the rear from moving at all... and/or make your scenario even worse. be cautious when shortening your chain, and straightening your hanger...