free to fixed....

Mr. Freeman

I recently had a mishap involving a bent and broken rear derailler, and possible spoke damage. The derailler is beyond repair. I'm thinking that this may be a good time to modify my bike into something a little simpler.

It's a Trek 7100 Hybrid bike with 7 cogs and a triple crankset. I'm think drop handlebars, brakes and levers for the drops, and a fixie setup in the back. sounds easy, but I know almost nothing about SS drivetrains.

So what do I need to know, and what would I have to do, to modify my freewheel into a singlespeed? is it even possible? is it even a good idea (I live in a relatively hilly coastal area. hills and wind, ugh )?

please, any and all input would be appreciated.

thanks in advance,

Mr. Freeman

__________________
"Winners forget during a race; They just love to run." ~Simon Weilder, Played by actor Joe Pesci, from "With Honors"

alfeng

Because you live in a hilly area, the first thing you have to decide is which of the three chainrings you were using the most.

If it was the middle, then I would arbitrarily attach the chain to the cog on your cassette/freewheel that as close to being in line with it (the middle chainring) -- this is just a starting point to find a gearing that suits you.

REMOVE THE EXTRA LINKS IN THE CHAIN (but, save them) ... if the chain runs through the derailleur, smoothly-enough, then you can leave it in place for the time being as you manually select (using the stops) the cog the chain runs on OR "borrow" another derailleur for the testing period.

Take your bike for a ride, and see how that gear combination works for you. Don't worry about the slightly slack chain ... as long as the chain is on the aligned cog & chainring, it shouldn't come off.

After a ride, or two, you will probably know if you want a higher or lower gear.

If a lower gear, try the chain on the granny & the cog which is aligned with it. Too easy OR just right?

When you think you've narrowed the options down to ONE, then you can go and buy a BMX freewheel OR ...

If it is a cassette, then you simply remove the unwanted cogs, and stack a couple of extra spacers on the freehub to take up the slack AFTER you have aligned the selected cog with your chainwheel.

If your rear wheel has a freewheel, then get a BMX freewheel which most closely approximates the tooth count you want. At some point, you want to re-dish the wheel so that the BMX cog is aligned with the chainring ... or, figure out how to get the chainring aligned with the cog (e.g., shorter spindle OR a larger chainring that fits on the inner BCD mounts)

While a FIXIE & a single-speed are related, the former uses a TRACK cog ... and, requires either a TRACK hub or a flip-flop hub (one side accepts a freewheel, and the other side can accept a drum brake OR a track cog + lockring).

FIXIEs don't let you coast ... so, they are better suited for flatlander riding.

BMX-or-platform pedals are probably better ... at first.

Just a reminder that there's an entire forum you can scan & query.

tinydr

Sorry to hear about the derailleur-hanger mishap...

I haven't seen the 7100... does it have vertical rear drop-outs
or fairly conventional forward facing (long) rear dropouts? Having
horizontal dropouts really makes life easier.

As to whether a fixed-gear is good for hilly coastal areas... I'd have to say
a flip-flop hub (fixed on one side, single on the other) would be ideal if you'll be running brakes anyway. Geared well, you can really climb on a fixed... but you do give up overall speed. But then, you could go with a smaller singlespeed cog and a slightly larger fixed cog... the best of both worlds.

I'm also not clear on the geometry of the 7100 and how it would mesh with a fixed... I'll have to take a look-see.

Tim