Fixie conversion

MartinM said:

I have an old racer which I use for taking on the train, and am
thinking of doing a cheapo fixie conversion

I think we've been here before...

# I once had a whim and I had to obey it
# To build up a fixer from second-hand stock...

Guy
--
May contain traces of irony. Contents liable to settle after posting.
http://www.chapmancentral.co.uk

88% of helmet statistics are made up, 65% of them at Washington
University

"MartinM" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I have an old racer which I use for taking on the train, and am
thinking of doing a cheapo fixie conversion (ie just put the chain on
one ring and use the small ring at the front). It has Horizontal
dropouts so chain tension not an issue. For general commuting what sort
of ratio should I use?
TIA

That's a matter of personal preference really; it depends on how fast you go
and how fast you like to pedal.

As an example, let's say you ride at an average of 24kph and your preferred
cadence is 80rpm. That means each pedal revolution needs to take you 5m.
Assuming your wheel circumference is 2.2m then you need a ratio of 2.27. A
42 chainring and 19 sprocket would be close enough.

Ian

MartinM said:

I have an old racer which I use for taking on the train, and am
thinking of doing a cheapo fixie conversion (ie just put the chain on
one ring and use the small ring at the front). It has Horizontal
dropouts so chain tension not an issue. For general commuting what sort
of ratio should I use?

Depends a bit on whether you spin or like to push, but generally
something in the mid 60's would be about right, OK on the flat uphills
and you wouldn't spin out too much on the descents.
If you have a 42 or 44 inner then a 17 or 18 rear cog respectively would
give you such a gear.
Personally I always prefer a gear in the low 70"s for general riding as
I don't like the discomfort of bouncing around on the saddle on downhills

You will need to check chain line and make sure the outer ring (if you
have to leave it on) doesn't interfere.
Have a look at Sheldons calcuator and work out your best combinations.

http://www.sheldonbrown.com/gears/

John B

"MartinM" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I have an old racer which I use for taking on the train, and am
thinking of doing a cheapo fixie conversion (ie just put the chain

on

Quoted message said:

one ring and use the small ring at the front). It has Horizontal
dropouts so chain tension not an issue. For general commuting what

sort

Quoted message said:

of ratio should I use?
TIA

When I made myself a fixie, twenty years or so ago now, I didn't know
the answer, so I got myself a couple of different cogs so I could
mess around, and change gear depending on my mood on any given day.
If I were doing it again (I should, I should), I think I would get
three sizes, somewhere round about 62", upper 60s somewhere, and low
70s. The low 60s is only because I'm now old enough to have a bus
pass, and right now have one or two problems which have left me
seriously out of shape. I'd think about it some more, trying it on
my normal bike, before actually committing myself

Jeremy Parker

JohnB said:

MartinM said:

I have an old racer which I use for taking on the train, and am
thinking of doing a cheapo fixie conversion (ie just put the chain on
one ring and use the small ring at the front). It has Horizontal
dropouts so chain tension not an issue. For general commuting what sort
of ratio should I use?

Depends a bit on whether you spin or like to push, but generally
something in the mid 60's would be about right, OK on the flat uphills
and you wouldn't spin out too much on the descents.
If you have a 42 or 44 inner then a 17 or 18 rear cog respectively would
give you such a gear.
Personally I always prefer a gear in the low 70"s for general riding as
I don't like the discomfort of bouncing around on the saddle on downhills

You will need to check chain line and make sure the outer ring (if you
have to leave it on) doesn't interfere.
Have a look at Sheldons calcuator and work out your best combinations.

http://www.sheldonbrown.com/gears/

John B

I ride a 73" gear (42 x 15) which although flat where I live is a bit
grumpy some days .......... I have just bought a 16T and 17T sprocket
to change down to a 63" ish gear.

Cyclo fixed sprockets are adequate, raher that the more expensive Dura
Ace track make.

St John Street Cycles [[email hidden]]

Jack Ouzzi said:

JohnB said:

MartinM said:

I have an old racer which I use for taking on the train, and am
thinking of doing a cheapo fixie conversion (ie just put the chain on
one ring and use the small ring at the front). It has Horizontal
dropouts so chain tension not an issue. For general commuting what sort
of ratio should I use?

Depends a bit on whether you spin or like to push, but generally
something in the mid 60's would be about right, OK on the flat uphills
and you wouldn't spin out too much on the descents.
If you have a 42 or 44 inner then a 17 or 18 rear cog respectively would
give you such a gear.
Personally I always prefer a gear in the low 70"s for general riding as
I don't like the discomfort of bouncing around on the saddle on downhills

You will need to check chain line and make sure the outer ring (if you
have to leave it on) doesn't interfere.
Have a look at Sheldons calcuator and work out your best combinations.

http://www.sheldonbrown.com/gears/

John B

I ride a 73" gear (42 x 15) which although flat where I live is a bit
grumpy some days .......... I have just bought a 16T and 17T sprocket
to change down to a 63" ish gear.

Cyclo fixed sprockets are adequate, raher that the more expensive Dura
Ace track make.

St John Street Cycles [[email hidden]]

be careful with Cyclo fixed sprockets, they are only pressed (teeth and
thread) and as such are not perfectly round/centred. They also have a
habit of stripping the threads on hubs if enough effort is put in on
hills. Try getting some old Villiers ones from bike jumbles for a
couple of pound.