Singlespeeding an MTB

[TheSandwichMonster]

So I've got an old MTB that I want to convert to SS for commuting and general pootling about on. I'm happy to do the work myself, but I just want to clarify what I actually need in terms of both parts and jobs to achieve this.

The bike is currently full XT (21 speed), circa 1996, complete with short cage rear derailleur. As far as I understand it, I need to select my gear ratio (any suggestions for a newbie about where to start?), remove all but one of the sprockets from the rear cassette, use some form of spacer arrangement to position it on the freewheel to give a decent chainline (any suggestions for what to use for spacers?), then disassemble the front chainrings and reassemble with just the single ring that I require. Finally I need to use some form of device or halflinks to maintain chain tension

Does that sound about right, or am I missing something fundamental?

 

[simon.r]

As far as I understand it, I need to select my gear ratio (any suggestions for a newbie about where to start?

'Normal' gear ratio for off-road is 2:1 (e.g. 32 tooth chainring / 16 tooth sprocket), for road (700c wheels) is 2.75:1 (e.g. 44 / 16). I'd suggest you start somewhere within that range and then adjust up or down depending on how you get on.

remove all but one of the sprockets from the rear cassette, use some form of spacer arrangement to position it on the freewheel to give a decent chainline (any suggestions for what to use for spacers?)

The easiest and quickest way to sort the back wheel is to buy an off the shelf kit that includes a sprocket and a number of spacers so you can adjust the chainline - something like this: http://www.jejamescycles.co.uk/onza-single-speed-item124146.html I'd go for a kit that includes several thin spacers rather than just two wide ones, so you can fine-tune the chainline.

then disassemble the front chainrings and reassemble with just the single ring that I require.

Yes - you may need a selection of shims (aka washers) to fine-tune the position of the ring and to compensate for the fact that outer chainring bolts are generally designed to hold two rings in place.

Finally I need to use some form of device or halflinks to maintain chain tension

Yes - either a purpose made tensioner, or use your old derailleur by adjusting the high and low limit screws and tension it using a short length of cable. I've no experience of half-links so can't comment on that method.

Does that sound about right, or am I missing something fundamental?

Yes, you're missing the fact that you'll get hooked and need to buy a ss specific frame, wheel, freewheel and chainset

 

[GrumpyGregry]

charliethebikemonger will tell you and sell you all you need.

velosolo will sell similar.

welcome to a world of fettling.

 

[TheSandwichMonster]

Thanks folks.

I'm already keeping my eye out for a track frame so I can also have a fixed!

 

[simon.r]

Thanks folks.

I'm already keeping my eye out for a track frame so I can also have a fixed!

Absolutely nothing wrong with having another bike, but a flip-flop hub - http://www.edinburghbicycle.com/products/budgetr-rear-fixed-wheel-700c-flip-flop-hub (as an example, loads of other brands available) will enable you to swap between fixed and freewheel on the same frame. It's generally considered that you shouldn't use chain tensioners on a fixed wheel tho' - the late great Sheldon Brown explains why towards the bottom of this page - http://sheldonbrown.com/singlespeed.html

Another option that looks interesting is an eccentric hub - http://www.whiteind.com/rearhubs/singlespeedhubs.html This would do away with the need for a chain tensioner altogether.

 

[TheSandwichMonster]

Thanks Simon.

I'd looked into going fixed with this bike, but the lack of horizontal dropouts and the relative expense of eccentric hubs or bottom brackets made it seem like a proper faff to be honest. I'd rather just single speed this one, and then look to get another later on down the line for fixed.