Fixed gear questions

Mark said:

Hi

I'm considering turning an old bike I have into a fixer for winter use.
Can I just replace the screw-on block with a single sprocket and
lockring for an inexpensive rear wheel? I'd need to replace the QR axle
with a longer nutted version but my main worry is that the chainline
will be miles off.

That's what I did. The fixed sprocket I used has a step on one side,
so it gives a different chainline depending on whichway round it's
mounted.

Quoted message said:

The dropouts on the frame (a Viscount, if anyone's heard of them) face
forward and down a bit. Is that okay?

Should do it.

Quoted message said:

Last question: any recommendations for cheap 42t chainsets?

I used the inner ring of the double chainset on the donor bike.

Tim

Mark said:

Hi

I'm considering turning an old bike I have into a fixer for winter use.
Can I just replace the screw-on block with a single sprocket and
lockring for an inexpensive rear wheel?

Yes you can, but you run the risk of unscrewing the sprocket if you resist
the pedals. It should be fine to start with though.

Quoted message said:

I'd need to replace the QR axle
with a longer nutted version but my main worry is that the chainline
will be miles off.

Chainline can be adjusted with cassette spacers behind the sprocket or by
shortening/lengthening the bottom bracket axle, if you can find
replacements for a cup and cone or stretch to buying a new cartridge
system.

However, if you are looking at spending any money I'd buy a Sovus flip-flop
track hub from SJS and some new spokes to rebuild your wheel.

Quoted message said:

The dropouts on the frame (a Viscount, if anyone's heard of them) face
forward and down a bit. Is that okay?

Should be fine. I use a Raleigh frame with similar dropouts on my fixed. Buy
yourself some proper serrated nuts and two long-handled wrenches for
fitting the rear wheel- makes things much easier.

Quoted message said:

Last question: any recommendations for cheap 42t chainsets?

I use a Dotek single speed chainset I got off eBay for a tenner. It's quite
heavy, but nice and stiff, unlike the chainset that came with the frame.
Investigate your LBS's bits box, there may well be something suitable in
there.

Regards,

-david

Mark said:

I'm considering turning an old bike I have into a fixer for winter
use. Can I just replace the screw-on block with a single sprocket and
lockring for an inexpensive rear wheel? I'd need to replace the QR
axle with a longer nutted version but my main worry is that the
chainline will be miles off.

You might well get away with using the QR axle but will have to fafe around
with the spaces to get the chainline right. If you get a cheap or used axle
you can use the spacers from taht and file/saw or grind them to get it just
right

Quoted message said:

The dropouts on the frame (a Viscount, if anyone's heard of them) face
forward and down a bit. Is that okay?

Sound like the best sort.

Quoted message said:

Last question: any recommendations for cheap 42t chainsets?

Get a cheap double and leave the big ring as a trouser guard or get some
single chainring bolts.

--
Andy Morris

AndyAtJinkasDotFreeserve.Co.UK

Love this:
Put an end to Outlook Express's messy quotes
http://home.in.tum.de/~jain/software/oe-quotefix/

Mark said:

I'm considering turning an old bike I have into a fixer for winter use.
Can I just replace the screw-on block with a single sprocket and
lockring for an inexpensive rear wheel? I'd need to replace the QR axle
with a longer nutted version but my main worry is that the chainline
will be miles off.

Yes it should work. You can adjust the chainline with spacers if need
be, both on the hub itself or at the bb end.
Using a 'lockring' won't do that much as the threading is the same as
the sprocket. I would advise fitting two brakes.

Quoted message said:

The dropouts on the frame (a Viscount, if anyone's heard of them) face
forward and down a bit. Is that okay?

It will be fine - unless its one of the very old Viscounts which ISTR
came with dodgy alloy forks.

Quoted message said:

Last question: any recommendations for cheap 42t chainsets?

Sorry can't help there. My winter fixed ibikes have always been made up
of old spares from the dark corners of ye shed.

John B

David Nutter said:

Mark said:

Hi

I'm considering turning an old bike I have into a fixer for winter use.

Quoted message said:

Quoted message said:

Should be fine. I use a Raleigh frame with similar dropouts on my fixed. Buy

yourself some proper serrated nuts and two long-handled wrenches for
fitting the rear wheel- makes things much easier.

....and make sure that you take one of the wrenches out on every trip, in
case you ever need to change an inner tube.

John B

John B said:

Mark said:

I'm considering turning an old bike I have into a fixer for winter use.
Can I just replace the screw-on block with a single sprocket and
lockring for an inexpensive rear wheel? I'd need to replace the QR axle
with a longer nutted version but my main worry is that the chainline
will be miles off.

Yes it should work. You can adjust the chainline with spacers if need
be, both on the hub itself or at the bb end.
Using a 'lockring' won't do that much as the threading is the same as
the sprocket. I would advise fitting two brakes.

Quoted message said:

The dropouts on the frame (a Viscount, if anyone's heard of them) face
forward and down a bit. Is that okay?

It will be fine - unless its one of the very old Viscounts which ISTR
came with dodgy alloy forks.

Quoted message said:

Last question: any recommendations for cheap 42t chainsets?

Sorry can't help there. My winter fixed ibikes have always been made up
of old spares from the dark corners of ye shed.

John B

A lockring is the opposite thread (lefthanded) and slightly less
diameter than the sprocket thread, otherwise how does it go on. I don't
know of any 'lockrings' suitable for the sprocket threads

--
..... it's not difficult, it's not exactly rocket salad

Pete Whelan said:

A lockring is the opposite thread (lefthanded) and slightly less
diameter than the sprocket thread, otherwise how does it go on. I don't
know of any 'lockrings' suitable for the sprocket threads

whether it is effective is open to debate, but any LH bracket cup
lockring will fit.
--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

Pete Whelan said:

John B wrote:

Quoted message said:

Quoted message said:

Using a 'lockring' won't do that much as the threading is the same as
the sprocket. I would advise fitting two brakes.

A lockring is the opposite thread (lefthanded) and slightly less
diameter than the sprocket thread, otherwise how does it go on. I don't
know of any 'lockrings' suitable for the sprocket threads

A bracket lockring seems to work.
However as it has the same threading as the sprocket its use is limited.

John B

John B said:

Mark said:

I'm considering turning an old bike I have into a fixer for winter
use. Can I just replace the screw-on block with a single sprocket
and lockring for an inexpensive rear wheel? I'd need to replace the
QR axle with a longer nutted version but my main worry is that the
chainline will be miles off.

Yes it should work. You can adjust the chainline with spacers if need
be, both on the hub itself or at the bb end. Using a 'lockring' won't
do that much as the threading is the same as the sprocket. I would
advise fitting two brakes.

Hm, okay. I thought that track hubs only had a single thread, onto which
sprocket and lockring went. I see that's not the case; track hubs have
stepped opposing threads. I had wondered what prevented the whole lot
unscrewing under backpedaling :~)

Building a wheel with a Souvos hub might be the best thing for me to do.

Quoted message said:

Quoted message said:

The dropouts on the frame (a Viscount, if anyone's heard of them)
face forward and down a bit. Is that okay?

It will be fine - unless its one of the very old Viscounts which ISTR
came with dodgy alloy forks.

There's rusty bits on the forks so I hope they're not alloy!

Quoted message said:

Quoted message said:

Last question: any recommendations for cheap 42t chainsets?

Sorry can't help there. My winter fixed ibikes have always been made
up of old spares from the dark corners of ye shed.

Others have recommended using one ring from the double on the bike,
which will work if the chainline is okay. As the outer ring is fixed to
the crank I can't mount the inner ring in the outer position so I may
have to do some more hunting.

Cheers,

Mark

Quoted message said:

Quoted message said:

I had wondered what prevented the whole lot
unscrewing under backpedaling :~)

Under "normal" use - ie if you have at least one brake and don't try
anything clever, then two threaded the same way will hold tight.
However, if they unscrew it will be catastrophic, and will certainly
happen in an emergency situation, making it far worse. So good advice
would be: don't do it.

If you get a track hub it will be more expensive, but you'll be able to
get the chainline and the dish right from the start. If you use an
undersize one which has a long axle, like the Miche, then that gives
you the freedom to match the chainline to what you've got, more than a
full-width hub. What size is the Souvos?

Quoted message said:

Quoted message said:

As the outer ring is fixed to
the crank I can't mount the inner ring in the outer position

It's normal to use the inner position (or middle from a triple) anyway.
You could file the teeth off the big ring to give a neat look - but
don't consider this a "trouser guard"! Flapping trousers, laces, etc on
a fixed are the quick way to find yourself eating dirt.

John B said:

However as it has the same threading as the sprocket its use is limited.

Just a thought: would threadlocking compound on the sprocket and/or
lockring be any use? Or would it not be strong enough to do any good?

d.

iakobski said:

If you get a track hub it will be more expensive, but you'll be able to
get the chainline and the dish right from the start. If you use an
undersize one which has a long axle, like the Miche, then that gives
you the freedom to match the chainline to what you've got, more than a
full-width hub. What size is the Souvos?

Time for me to get my now fixed hub into the bike it is intended for..
It may take a bit of time to smooth out the bearing races after the
brazing, but it is definitely 'fixed' now.

And I can use my old Uniglide sprockets on it quite happily.

...d

davek said:

John B said:

However as it has the same threading as the sprocket its use is limited.

Just a thought: would threadlocking compound on the sprocket and/or
lockring be any use? Or would it not be strong enough to do any good?

d

I don't thinkit could hurt, but I wouldn't stake my life on it
either...

I've seen one example where epoxy resin was used to lock the ring in
place, then more to lock a bottom bracket lockring over it.
Messy, but it has worked for several years without problems.
You'd want to make sure that the ring was the right tooth count for the
gear you want to end up with.
If the sprocket gets worn out, or you break drive side spokes (and
can't thread a new one in around the sprocket), or want to change the
spacing, or whatever, about the only way to shift the epoxy is
significant heat, and or nasty solvents (actone, but that's only
effective while the epxoy is still fairly new).

It's up to you, but personally, I wouldn't chance it. Chain coming
off, sprocket unscrewing etc. at speed on a fixie is supposed to be an
interesting [1] event, and a new track hub and spokes are cheap
compared to new skin.

Regards,

bookieb

[1] For several bloody and painful values of interesting.

davek said:

John B said:

However as it has the same threading as the sprocket its use is limited.

Just a thought: would threadlocking compound on the sprocket and/or
lockring be any use? Or would it not be strong enough to do any good?

Would a couple of blobs of weld do it, the makita them flat?

But isn't it possible to just use a std cassette, and shuffle the
sprockets till you get the best ratio on the best chain line? Oh, and
a DH chain tensioner, I guess?

sothach said:

davek said:

John B said:

However as it has the same threading as the sprocket its use is limited.

Just a thought: would threadlocking compound on the sprocket and/or
lockring be any use? Or would it not be strong enough to do any good?

Would a couple of blobs of weld do it, the makita them flat?

I've done this to a freehub.. filled it with braze so it most certainly
doesn't freewheel any more.

Quoted message said:

But isn't it possible to just use a std cassette, and shuffle the
sprockets till you get the best ratio on the best chain line? Oh, and
a DH chain tensioner, I guess?

You'd probably want two, one for above the chain and one for below, and
you would get some slop in the system that could be very 'interesting'.

...d

Quoted message said:

But isn't it possible to just use a std cassette, and shuffle the
sprockets till you get the best ratio on the best chain line? Oh, and
a DH chain tensioner, I guess?

Are you getting the meanings of "fixed" and "fixed" confused - the thread is
about "fixed fixed" - i.e. no freewheeling, pedals turn all the time rather
than "fixed" in the sense of single-speed being fixed in one gear.

Having just built a fixed I looked at various options (although not the
"glue the cog on" method!) and ended up cutting my losses and buying a pukka
wheel for fixed with flip-flop hub and proper sprockets + lockrings ...
although I did put a brake on the back too. One saving was to convert a
double chainset by using just the inner cog with shorter bolts. All works a
treat.

RG

sothach said:

But isn't it possible to just use a std cassette, and shuffle the
sprockets till you get the best ratio on the best chain line? Oh, and
a DH chain tensioner, I guess?

That would work for single-speed, but not for fixed.

--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
A complimentary biro(tm) is /not/ to be sniffed at.

iakobski said:

Quoted message said:

Quoted message said:

I had wondered what prevented the whole lot unscrewing under
backpedaling :~)

Under "normal" use - ie if you have at least one brake and don't try
anything clever, then two threaded the same way will hold tight.
However, if they unscrew it will be catastrophic, and will certainly
happen in an emergency situation, making it far worse. So good advice
would be: don't do it.

What exactly does happen? I have very little exposure to fixed wheel
bikes but my guess would be that the sprocket unscrews and jams the
chain against the dropout or stays, locking the rear wheel and putting
the rider on the deck very quickly.

Quoted message said:

If you get a track hub it will be more expensive, but you'll be able
to get the chainline and the dish right from the start. If you use an
undersize one which has a long axle, like the Miche, then that gives
you the freedom to match the chainline to what you've got, more than a
full-width hub. What size is the Souvos?

It's 110mm OLN with a 152mm axle. I presume (but haven't bothered to
measure yet) that the dropout spacing on my frame is 126mm. SJS claim
a longer axle is needed for OLN lengths of more than 121mm.

Quoted message said:

Quoted message said:

Quoted message said:

As the outer ring is fixed to the crank I can't mount the inner ring
in the outer position

It's normal to use the inner position (or middle from a triple)
anyway. You could file the teeth off the big ring to give a neat look
- but don't consider this a "trouser guard"! Flapping trousers, laces,
etc on a fixed are the quick way to find yourself eating dirt.

I'll bear that in mind!

Thanks,

Mark

Quoted message said:

davek said:

John B said:

However as it has the same threading as the sprocket its use is limited.

It's up to you, but personally, I wouldn't chance it. Chain coming
off, sprocket unscrewing etc. at speed on a fixie is supposed to be an
interesting [1] event, and a new track hub and spokes are cheap
compared to new skin.

Quoted message said:

[1] For several bloody and painful values of interesting.

I rode a couple of winters with a fixed on a seven speed freewheel hub
without a lockring - except as a spacer. The sprocket gets screwed on
/very/ tightly by riding and you can put a lot of back pressure on it.
You are never likely to want to put enough pressure on it to cause it
to unscrew. I once had a chain jump off due to bad chainline and a
cheap sprocket.

For a drop handlebar machine fit two brakes; you are going to want two
hoods to ride on.
--
Phil Cook looking north over the park to the "Westminster Gasworks"