Singlespeed GT (again)

I've got an old-ish GT Talera that I want to convert
into a SS mtb (yes, the same as last time before it
became a trials bike).
It has vertical dropouts and 7spd AceraX components.
There are many options for the conversion but I want
to do it as cheap as possible (the bike was less than
$300).

I would MUCH prefer to do the conversion without a
bodged derailer or chain tensioner.

I've spotted FixMeUp! software online
(http://www.peak.org/~fixin/tutorial3.html)
that will calculate gear sizes and chain length for a
particular chainstay length, so as to get the chain
tension correct in vertical dropouts.

I would basically use an existing cassette (actually just
1 sprocket from one) or a bmx sprocket.
Not sure how I will do the chainring because the
AceraX one seems to detach the outer two sprockets
as a single piece? Maybe I can get a new, single,
bolt-on one?
Chainline will be fixed with spacers on the cassette I
guess, but what sort?

Anyway, if none of this goes to plan I am going to
looking for prices on a couple of other options,
namely:
- OnOne Inbred frame
- White Industries ENO Eccentric Hub

If you have any suggestions for how best to setup this
GT without resorting to throwing money at it, that'd be
great.

hippy

"
I would basically use an existing cassette (actually just
1 sprocket from one) or a bmx sprocket.

snip....

If you have any suggestions for how best to setup this
GT without resorting to throwing money at it, that'd be
great.

hippy

I made single speeds out of 2 GT frames, both 18".
What I found was that running 34 - 17 gears was a perfect fit, and ddn't
need a singulator ( which I just bought!).
Looks nice clean and simple too.

Dave

"
I would basically use an existing cassette (actually just
1 sprocket from one) or a bmx sprocket.

snip....

If you have any suggestions for how best to setup this
GT without resorting to throwing money at it, that'd be
great.

hippy

I made single speeds out of 2 GT frames, both 18".
What I found was that running 34 - 17 gears was a perfect fit, and ddn't
need a singulator ( which I just bought!).
Looks nice clean and simple too.

Dave

"hippy" wrote in message
...
"Dave@fnq" wrote in message
...
I made single speeds out of 2 GT frames, both 18".
What I found was that running 34 - 17 gears was a perfect fit, and
ddn't
need a singulator ( which I just bought!).
Looks nice clean and simple too.

I had a look at my Avanti and I ride mostly with the middle
ring (32 teeth I think?) and gear '5' on the 8spd cluster which
is 17T. I would probably use '6' which is 15T but that's the
one missing all the teeth!
I might see if I can get hold of an old 34T chainring to try.
Did you swap your cranks to do this - or can I just bolt
an aftermarket chainring onto the AceraX cranks?
Any idea on the chainstay length of your GT's?

thanks muchly dave!!
hip

I used the cranks I had, just took off the granny and big rings.
Unfortunatly i've sold the GT frames before I last moved so no longer have
them, but i'm sure there is someone here who has an 18" GT who can tell
you.
I used a Zaskar and a Polomar , and both had the same chainstay length.
Remember the size of the front and back rings is not so important, but the
RATIO is.
I chose 34 - 17 because I thought a 2:1 ratio was a good starting point,
and just got lucky that they fit perfectly on an 18" GT frame.
People warned me about chain stretch and slippage with out the singulator,
but it was never a problem.
One hint though, I found using bigger rings/ cogs to achieve the same ratio
is a better way to go. So a 34 - 17 combo is better than a 22-11 combo, even
though they have the same ratio of 2:1. (I think this is because the chain
doesn't have such a tight turn at the rear wheel, so seems easier to pedal,
plus the ring/ cog should last longer because of less wear).

Dave

"hippy" wrote in message
...
"Dave@fnq" wrote in message
...
I made single speeds out of 2 GT frames, both 18".
What I found was that running 34 - 17 gears was a perfect fit, and
ddn't
need a singulator ( which I just bought!).
Looks nice clean and simple too.

I had a look at my Avanti and I ride mostly with the middle
ring (32 teeth I think?) and gear '5' on the 8spd cluster which
is 17T. I would probably use '6' which is 15T but that's the
one missing all the teeth!
I might see if I can get hold of an old 34T chainring to try.
Did you swap your cranks to do this - or can I just bolt
an aftermarket chainring onto the AceraX cranks?
Any idea on the chainstay length of your GT's?

thanks muchly dave!!
hip

I used the cranks I had, just took off the granny and big rings.
Unfortunatly i've sold the GT frames before I last moved so no longer have
them, but i'm sure there is someone here who has an 18" GT who can tell
you.
I used a Zaskar and a Polomar , and both had the same chainstay length.
Remember the size of the front and back rings is not so important, but the
RATIO is.
I chose 34 - 17 because I thought a 2:1 ratio was a good starting point,
and just got lucky that they fit perfectly on an 18" GT frame.
People warned me about chain stretch and slippage with out the singulator,
but it was never a problem.
One hint though, I found using bigger rings/ cogs to achieve the same ratio
is a better way to go. So a 34 - 17 combo is better than a 22-11 combo, even
though they have the same ratio of 2:1. (I think this is because the chain
doesn't have such a tight turn at the rear wheel, so seems easier to pedal,
plus the ring/ cog should last longer because of less wear).

Dave

"Dave@fnq" wrote in message
...
I used the cranks I had, just took off the granny and big rings.

I'll see how I go with what I've got on it, otherwise I might have to
upgrade.
To the parts bin!!! ;-)

Remember the size of the front and back rings is not so important, but the
RATIO is.
I chose 34 - 17 because I thought a 2:1 ratio was a good starting point,
and just got lucky that they fit perfectly on an 18" GT frame.

Yeah, I realise 2:1 is the generally accepted starting point, but I'm more
concerned with getting something that fits the frame without any need
for a chain tensioner. Getting close to 2:1 is certainly a consideration,
but it doesn't have to be exactly that.

One hint though, I found using bigger rings/ cogs to achieve the same
ratio
is a better way to go. So a 34 - 17 combo is better than a 22-11 combo,
even
though they have the same ratio of 2:1. (I think this is because the chain
doesn't have such a tight turn at the rear wheel, so seems easier to
pedal,
plus the ring/ cog should last longer because of less wear).

Yep, I agree. I planned to try 32/16 first, simply because I could do that
with only a bmx sprocket and some spacers needed (assuming tension
was ok). I think it might be a bit of a hit and miss game trying to match
chain length and front and rear sprocket sizes to get correct tension.
Going 22/11 though does mean lighter weight and better chainring
ground clearance, but these are not major concerns for me.

You've sold them now but did you ride your GT's much?
What did you think of them when they were setup as SS?

cheers
hippy

"Dave@fnq" wrote in message
...
I used the cranks I had, just took off the granny and big rings.

I'll see how I go with what I've got on it, otherwise I might have to
upgrade.
To the parts bin!!! ;-)

Remember the size of the front and back rings is not so important, but the
RATIO is.
I chose 34 - 17 because I thought a 2:1 ratio was a good starting point,
and just got lucky that they fit perfectly on an 18" GT frame.

Yeah, I realise 2:1 is the generally accepted starting point, but I'm more
concerned with getting something that fits the frame without any need
for a chain tensioner. Getting close to 2:1 is certainly a consideration,
but it doesn't have to be exactly that.

One hint though, I found using bigger rings/ cogs to achieve the same
ratio
is a better way to go. So a 34 - 17 combo is better than a 22-11 combo,
even
though they have the same ratio of 2:1. (I think this is because the chain
doesn't have such a tight turn at the rear wheel, so seems easier to
pedal,
plus the ring/ cog should last longer because of less wear).

Yep, I agree. I planned to try 32/16 first, simply because I could do that
with only a bmx sprocket and some spacers needed (assuming tension
was ok). I think it might be a bit of a hit and miss game trying to match
chain length and front and rear sprocket sizes to get correct tension.
Going 22/11 though does mean lighter weight and better chainring
ground clearance, but these are not major concerns for me.

You've sold them now but did you ride your GT's much?
What did you think of them when they were setup as SS?

cheers
hippy

You've sold them now but did you ride your GT's much?
What did you think of them when they were setup as SS?

cheers
hippy


I only rode them to and from work on the road and short trips into the city
(a bonus for me was that they had rigid forks).
Maybe I should have tried them off-road, but I thought I might be too soft
for a rigid single speed after riding a geared duelly for so long! :-)
The first thing that struck me on the first ride was how quiet it was! You
don't realise how noisy a geared bike can be.
The next thing was I kept going to change gears every time I got near a hill
(up and down).
With all this talk of single speeds I might change my hard tail into one!
(also a GT).
Where I live now (Cairns) is pretty flat around town so it is perfect for
one.

Dave

You've sold them now but did you ride your GT's much?
What did you think of them when they were setup as SS?

cheers
hippy


I only rode them to and from work on the road and short trips into the city
(a bonus for me was that they had rigid forks).
Maybe I should have tried them off-road, but I thought I might be too soft
for a rigid single speed after riding a geared duelly for so long! :-)
The first thing that struck me on the first ride was how quiet it was! You
don't realise how noisy a geared bike can be.
The next thing was I kept going to change gears every time I got near a hill
(up and down).
With all this talk of single speeds I might change my hard tail into one!
(also a GT).
Where I live now (Cairns) is pretty flat around town so it is perfect for
one.

Dave

"Dave@fnq" wrote in message
...
I only rode them to and from work on the road and short trips into the
city
(a bonus for me was that they had rigid forks).

Same here, at least until I get better chain tension for off-road use.
Dropped
chain 5 times riding the 52k return trip to work on Sat. Not bad, but no
good
for off-road use.

Here it is:
http://www.openwindows.com.au/hippy/...gtss/index.htm

I didn't have enough spacers so there are still sprockets on the back, but
they
are unusable - purely for spacing until i find some more dead cassettes to
pull
apart. Brakes need some tweaking too as well as the general riding position.
I'll get there...

Maybe I should have tried them off-road, but I thought I might be too soft
for a rigid single speed after riding a geared duelly for so long! :-)
The first thing that struck me on the first ride was how quiet it was! You
don't realise how noisy a geared bike can be.

Mine is pretty quiet except for the pedals. They have no bearings in them,
I'm sure! But hey, they were free from my LBS (along with the cranks and
cassette for the rear sprocket) so I no complain! ;-)
I'm going to replace the chain and the chainring with new ones so that
should
up the tension a little bit as well as making it quieter/smoother with
ramp-less
teeth.

The next thing was I kept going to change gears every time I got near a
hill
(up and down).

Well, I was riding my 24spd HT to and from work without changing gears
so I think I will manage when there are no gears to change! :-)
I was practicing SS riding to see which gear ratio I liked.

With all this talk of single speeds I might change my hard tail into one!
(also a GT).

Do it! You know you want to! ;-)

Just to let anyone reading this thread know.. the SingleSpeed World
Championships are being held in Castlemaine, Victoria in November
this year.
See: http://www.atomic-industries.com

hippy