Cheap Singlespeeds. SS $100 bike, $200 bike. Walmart thruster. 6KU fixie. Bikesdirect Dawes Streetfighter SST

Singlespeed bikes.  The simplest type of bike.  If you live somewhere flat, hate maintenance, and like to pedal hard on hills, these are for you.

DON'T get a $129 walmart Thruster!!!

It's a pile.

The cheapest, decent quality singlespeed  is the $200 6KU.

The frame and fork are high tensile steel, which is a bit heavy, but is quite durable.  The wheels are nice, with super strong deep V rims, and good hubs.  The fork is threadless.  It fits fatter tires and fenders.  The cranks are pretty nice.  This is a good bike for $200.

There are even are a ton of frame and wheel color combinations to choose from, too.

http://www.citygrounds.com/fixed-gear-single-speed-bikes#brand=6ku

The main crappy things on this bike, things to upgrade to make it a more durable commuter.  Are the freewheel, it has junky chinese one that will fail.  The freewheel is the gear on the back wheel, that coasts and makes the clickity noise.  Good quality  ACS, Shimano, or GT ones are $15-25 dollars.

And the tires.  Good quality, flat resistant tires are key to a bike you ride everyday.  Continental gatorskins, Schwalbe Marathons, and Panaracer Paselas are all good tires, between $30-40.

At $230, you get the Bikesdirect Dawes Streetfighter.

This bike has a cromoly steel frame and fork, which is lighter and stronger, better quality.  Realistically, most people won't bend the hi-ten 6ku frame, and it is maybe 2 pound difference.  But the streetfighter is definitely the better frame. 

The tires and freewheel still need urgent replacement.  The seat, seatpost, bars are a bit junkier than the 6ku.  Not a huge deal, as these are parts many bike riders will replace anyways to make their bike fit better and more comfortably.

The $230 Dawes SST is similar bike, except with drop bars

Mongoose Stat 29" disc, $219

http://www.walmart.com/ip/29-Mongoose-Stat-Men-s-Mountain-Bike/21191093

Mongoose Stat
-Aluminum frame, size 18"
-29" wheels, fast rolling, comfortable, good selection of tires
-disc brakes.  More consistent in wet weather.  The brakes don't wear out your rims, like rim brakes do.  Brake pads and rims last longer with disc brakes.

Is the stat a decent bike?  It sells for $220, and has been on sale for as low as $160.

The aluminum frame is pretty good quality, and has some nice details, especially for the price.  It has a common 1 1/8" headtube, 68mm euro bb shell, 27.2mm seatpost.  It comes in one size, 18".  Good for 5'8"-5'11" riders.

The fork is a very heavy, cheap, steel suspension forks.  This is one of the worst parts of the bike.  The good news is that it is 1 1/8" threadless steerer tube, the most common size.

A chromoly steel rigid fork would be a good replacement.  This is simpler, lighter, no maintenance, easier to fit fenders.  You don't want shocks on a commuter bike.
This $50 Nashbar fork is a good choice.  Axle to crown: 453mm.

The Stat uses 1 1/8" stem, with 25.4mm handlebar.  These are the most common sizes.  Easy to swap out different styles of handlebars, or different length stems.
Stems are <$20
Bars are $15-35 depending on style.

The wheels use Quando aluminum quick release hubs, F&R.  It uses a freewheel in the rear.  Double wall 29" aluminum rims.  These are pretty nice wheels.
The tires are cheap, knobby tires.  They roll slow, and get flats easily.  Faster rolling, more flat resistant commuter tires are the best change you can make to this bike.  Continental, Michelin, Vittoria, Rubena make nice 29x2.0" fatty city tires for around $20-30 per wheel

29" rims and 700c rims are the same diameter, and their tires are usually interchangeable.  Both 29" and 700c rims have the same 622mm ERTO diameter.  29" rims tend to be wider to work with fatter tires.  700c tend to be narrower to work with skinnier tires.
29" tires are measured width in inches, for example 2.0".
700c is by "c", bacially mm's.  23c= 23mm very skinny.  You can fit fatter 35c and up tires on 29" rims.

These Schwalbe 700 X 40c tires are a bit narrower and faster rolling.  40mm is about 1.6" wide, so they still have some cush.
$25 for the pair is a great deal.

Fenders are another thing to think about when choosing tires.  There are not that many fenders available for fatty 29X2+" tires.  The Planet Bike Cascadia fenders are an excellent choice, but pricey at $45.

More common sizes are 700X45mm fenders, $23.  These only fit smaller width 700c tires, 44c or lower.
Going this route, you are under $50 for good tires and fenders.

The Promax cable disc brake calipers are not terrible.  One bad thing is their brake pads are not commonly stocked at bike shops.

Replacement Cheap brake pads on ebay

Better brake calipers, that take commonly stocked brake pads would be a good upgrade for this bike.
Avid BB-5., $33  These are good brakes and brake pads are readily available for them.  The are better constructed, and easier to adjust.  The promax's are not bad, though.

The brake levers have a plastic body, with an aluminum lever blade.  They work, but they are flexier than levers with an aluminum lever body.  The cables and housing on the bike are poor quality.  Better levers and cables would really improve this bike.
Shimano Acera levers, including cables & housing, $14

The 3 X 7 speed SRAM grip shifters are good.  The shift cables & housing on the bike are poor quality.  Shimano, SRAM, Jagwire make good shift cables & housings.

Shimano Tourney derailleur.
7 speed freewheel & chain.  Drivetrains usually last about 3000 miles.  The replacement parts for this bike are very inexpensive.  The chain and freewheel on the bike are cheap chinese.
The 7 speed freewheel costs $12 to replace with good quality shimano one.
Better quality SRAM chain is $8.
This bike has one of the most affordable drivetrains to replace.

The cranks are chinese, aluminum arms, with stamped steel rings.  They are not light, but they are durable.  The bottom bracket is euro threaded adjustable loose ball.  Replacement shimano cranks are around $40, and bottom brackets around $20.  Though I would expect the cranks to last awhile.

The pedals are pretty nice aluminum BMX pedals.  Most walmart bikes have janky plastic pedals, these ones are good.

The seat and post.  The quality of the seat is not terrible, but it is heavy and has a really tacky cover.  It is one of the cheapest looking things on the bike.

The seatpost is a cheap "seat guts" style post.  These are heavy and prone to creaking and slipping.

 A 2 bolt Kalloy 27.2mm seatpost would be a good upgrade for <$20.

Kalloy 2 bolt aluminum seatpost $14

Singleworks city limit, leather, $20

Overall, the bike is not a bad choice for a commuter.  The worst parts are the tires and fork.  The brakes would be better with quality levers and cables.  Decent seat and post would save weight, look better.
Tires= $25
Fenders= $22
-------------------
Fork= $50
Levers= $13
Seat & post= $34
$144 total.

Schwinn Admiral 700c 7 speed, fenders, rack $159

$159, the Schwinn Admiral is one of the best value commuter bikes you can get at Walmart.
http://www.walmart.com/ip/700c-Schwinn-Admiral-Women-s-Hybrid-Bike-Powder-Blue/26999382
http://www.walmart.com/ip/700c-Schwinn-Admiral-Hybrid-Men-s-Leisure-Bike-Matte-Red/26999373

The Admiral has a high tensile steel frame and fork.
It has aluminum 700c wheels, that roll fast.
7 speed gripshift and shimano derailleur.
Aluminum linear pull brakes.
Upright sweptback handle bars and a beach cruiser seat.
Steel fenders and rear rack.

 Like most walmart bikes, it only comes in one size.  The men's model fits people 5'6"- 5'10".  The women's model fits 5'2-5'-6".

Walmart does not assemble bikes very well.  The same kid that puts together the BBQ grills, puts together the bikes.  Most bike shops are pretty honest.  Bring the bike to a shop, tell them you will be riding it to work and would like it safe, and they will take care of you for under $50.

One of the best features of the Admiral, are it's good quality, aluminum 700c wheels.  It has an alloy quick release front hub, and solid axle nutted freehweel rear.  700c aluminum rims can fit a wide selection of road, touring, and commuter tires. However, the schwinn tires that come on the bike are very cheap, do not take high pressure, and are prone to flat tires.  The best thing to do to this bike to make it a more reliable commuter is better tires.  Nothing ruins your day like flat tires.

Plan to buy better tires.  Good commuter tires are Continental, Schwalbe, Michelin touring.
These Vittoria 700X32c tire are slightly skinnier than the stock 35c tires.  $30 pair.
This is a great deal on Schwalbe Marathon 700x35c tires.  They are very tough to flat, and very long lasting.
Some of best commuter tires you can get. Blue Sky has them $40 for the pair.

The beach cruiser springer seat is made for cruising, not pedaling.  The springs are heavy and squeaky.  The seat is very wide and rubs on your legs when pedaling.
The seatpost with cheapie seat guts is heavy and prone to slipping and creaking.
I would suggest a better seat for $20-30 and an aluminum seatpost for $15-20.

http://www.blueskycycling.com/product7576_46_-WTB-Freedom-Econoline-Saddle.htm $33

The Avenir Classic has real leather cover, for $30.
http://www.amazon.com/Avenir-Classic-Series-Saddle-Black/dp/B003RLDH0E

Singleworks city limit, leather, $20

Kalloy 2 bolt aluminum seatpost

Seatposts come in many sizes.  It is important to check the size of your post to make sure you get the right size.  Luckily, the size is stamped at the bottom of the post.  Remove your post and look for marking:

This example, not the Schwinn, is stamped 26.8.   Post sizes are diameter X length.  This example post is 26.8mm.  Common length is 350mm or 35cm.  400mm is long.  250-300mm is short.  You can always cut a long post down.  Common diameters are 25.4, 26.0, 27.2, etc.  Make sure you get the right size!
Amazon is a good place to buy a post.  Search "kalloy" and "27.2" or "25.4" or whatever the correct size is.

The admiral uses a aluminum quill stem.
It's steel handle bars are swept back. They give you an upright, comfortable position.  Good for short trips.  If you are riding longer distance, lower, less swept back bars would put you in better position to cut through the wind.  The steel bars are quite heavy, and aluminum bar saves a lot of weight.
http://store.velo-orange.com/index.php/components/handlebars/vo-milano-handlebar-22-2-dia.html
It uses a gripshift 7 speed shifter, good quality.
Aluminum V-brake levers, also decent quality.
The brake and shift cables and housing are poor quality.  The cheap housings flex a lot, makes your brakes feel mushy and shifting vague.  Jagwire, Shimano, Sram make quality cables & housing that will drastically improve shifting and braking of the bike.
Brake cables & housing, $13

The aluminum V-brakes are functional, but not great quality.  The stock brake pads are very hard plastic-y compound.  The brakes themselves have play on the bosses and cheap plastic spring adjustment.  I would suggest upgrading to Shimano Acera brakes fore $14.  Not much more than $8 brake pads.

The drive train is basic, durable, and replacement parts are inexpensive.  The drivetrain is the crank and chainring, the chain, and the freewheel.  Drivetrains typically last around 3000 miles.  That sounds like a lot, but if you are riding 5 miles to work each way, that 10 miles a day, 300 days.  Tires, brake pads, and drivetrains are consumables.

It uses a steel one piece crank and steel sprocket.  This is heavy and crude, in comparison to three piece aluminum cranks that come on bike shop quality bikes, but it gets the job done, and is durable.  This style of crank is common on beach cruisers and kid's bikes.

The 7 speed freewheel costs $12 to replace with good quality shimano one.
Better quality SRAM chain is $8.
This bike has one of the most affordable drivetrains to replace.  The steel chainring, while heavy, is durable.
The Shimano Tourney derailleur is basic, and replacements are about $14.