Fixer

iakobski said:

I'm thinking of going fixed.

I've experimented with not changing gear over my normal route, and I
reckon 42/14 would be about right, except when it's really windy, when
I think I'd need 42/15.

It's VERY difficult to tell what fixed ratio will suit
by trying on a freewheel.

The fixed transmission (as opposed to fixed ratio)
alters your perception of the ratio.

If you're happy with a single-speed free at the 2
ratios you mention, I suspect that a "true" fixed
would make you happy with *either* ratio, removing
the need to find a double sided hub.

BugBear

"bugbear" <bugbear@trim_papermule.co.uk_trim> wrote in message
news:[email hidden]...

Quoted message said:

iakobski said:

I'm thinking of going fixed.

I've experimented with not changing gear over my normal route, and I
reckon 42/14 would be about right, except when it's really windy, when
I think I'd need 42/15.

It's VERY difficult to tell what fixed ratio will suit
by trying on a freewheel.

The fixed transmission (as opposed to fixed ratio)
alters your perception of the ratio.

If you're happy with a single-speed free at the 2
ratios you mention, I suspect that a "true" fixed
would make you happy with *either* ratio, removing
the need to find a double sided hub.

BugBear

I have ridden around on a 48x18 which is a slightly smaller gear(for the
hills) and this is pretty good as far as gearing goes. I didn't use a
lockring as i didn't have one and i have yet to have the sprocket unscrew
itself. you are more likely to bounce around on the saddle downhill as like
me your legs may fail to keep up with the pedals. Subsequently I have fitted
a lockring from an old bottom bracket as the hub is not for the track just
an old screw on freewheel.

cheers
Jon_H

iakobski said:

I'm thinking of going fixed.

Eeh, great. Do tell us here of the project!

Quoted message said:

I've experimented with not changing gear over my normal route, and I
reckon 42/14 would be about right, except when it's really windy, when
I think I'd need 42/15.

I used that method and then compromised a bit due to what was available.
I'm finding 47x18 a little tame now, so I might shrink the sprocket a
bit: I tried to allow for this by choosing a >16t sprocket.

You need to factor in wheel radius and crank length too, as described at
http://www.sheldonbrown.com/gain.html .

You're limited in what you can do by the length of the dropout or your
track ends. I wonder if there's anything to be said for using two master
links in the chain to get a greater spread between the two sides?

Quoted message said:

All the write-ups I've seen on the web that talk about flip-flop hubs
recommend fixed on one side and freewheel on the other. Is there any
particular reason for this?

If you give the free side a lower ratio, you get a useful low-effort
gear for getting home when you're knackered. That's it, basically.

Quoted message said:

Can I put fixed on both sides and do away with the need for a rear
brake?

Believe so: it's the Road Vehicle Construction and Use regs, 1986 IIRC:
you need two independent braking systems, and there's an exception which
counts a pure fixed transmission as a braking system for the driven
wheel.

It's great for controling your movement in slowish traffic - you can
just sort of balance or hover at the right speed. Okay for helping you
come to a standstill too, but not so good for stopping from a fast speed.

It's a good idea to use a clipless pedal system if you're doing this
though.

Quoted message said:

Also, lockrings. Necessary or not?

I'd say yes, especially on a pure fixed with no secondary rear brake.

--
Andrew Chadwick

iakobski <[email hidden]> wrote:

: All the write-ups I've seen on the web that talk about flip-flop hubs
: recommend fixed on one side and freewheel on the other. Is there any
: particular reason for this? Can I put fixed on both sides and do away
: with the need for a rear brake?

Phil Wood and others do double fixed hubs.

Personally I like a rear brake on a fixed, but not everyone does. If you
don't have a rear brake, you do need a locknut.

--
Arthur Clune PGP/GPG Key: http://www.clune.org/pubkey.txt
The struggle of people against power is the struggle
of memory against forgetting - Milan Kundera

iakobski said:

I'm thinking of going fixed.

I've experimented with not changing gear over my normal route, and I
reckon 42/14 would be about right, except when it's really windy, when
I think I'd need 42/15.

Since sprockets are cheap at under a fiver for the very cheapest,
cheese-based products, picking the wrong size is not a problem. Also, you
get quite adept at churning away on a fixed so don't worry too much about
picking an exactly perfect ratio. I ran 42/18 in Durham; perfect for the
hills round there but too low for round here (Lincolnshire) even when riding
into one of the Beastly Headwinds that seem to be a local speciality. I use
42/16 now. Though unpleasant, you could still ride in Durham with that
ratio.

Quoted message said:

All the write-ups I've seen on the web that talk about flip-flop hubs
recommend fixed on one side and freewheel on the other. Is there any
particular reason for this? Can I put fixed on both sides and do away
with the need for a rear brake?

You may, though if there is too much difference between the sprockets you
use (with either fixed/fixed or fixed/free) you might find the chain is too
long or too short.

I'd keep the rear brake even if you do have fixed both sides.

Quoted message said:

Also, lockrings. Necessary or not?

Define "necessary". I like to brake by resisting the pedals so a lockring is
undoubtedly necessary for me. I have one of the cheap Sovos track hubs (also
cheese-based) and it came with one lockring fitted. I wouldn't worry too
much if you plan a simple test-project using a hub suitable for threaded
freewheels.

Regards,

-david

Thanks for all the advice, folks.

Based on all this, I reckon I'll go for a single-sided hub, start at
about 2.8 ratio and move up if/when needed. A larger than 42 chain ring
sounds like a good idea to get more fine tuning on the ratio so I may
try to stretch the budget to include a chainset with 165 cranks just
for this project. I'll leave the rear brakes on for now, though I can't
remember the last time I used them while commuting - there's no
mountains, not really hills even.

Now to clear it with the finance director....

iakobski said:

I'm thinking of going fixed.

I've experimented with not changing gear over my normal route, and I
reckon 42/14 would be about right, except when it's really windy, when
I think I'd need 42/15.

This is a very personal choice and there is no right answer, it will
depend on you and the terrain. I use a 46-15 and where I ride it is
fairly hilly. You have three gears on a fixed, sitting, standing and
walking.

Quoted message said:

All the write-ups I've seen on the web that talk about flip-flop hubs
recommend fixed on one side and freewheel on the other. Is there any
particular reason for this? Can I put fixed on both sides and do away
with the need for a rear brake?

For my first fixed gear I bought one installed a 15 & 16 freewheel and
promptly never used the freewheel. I would'nt bother.

Quoted message said:

Also, lockrings. Necessary or not?

If you've got no rear brake yes. If you have I'd still use one as I have
managed to unscrew the cog a few times. This usually happens after you
become airborne, for instance hitting a large speed ramp at speed and
going into a rapidly decaying low earth orbit.

I would still fit a rear brake in hilly terrain though, I didn't use one
when riding it in London though.