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-   -   Making a fixed-wheel bike (http://www.cyclebanter.com/showthread.php?t=172058)

D.M. Procida October 19th 07 12:47 PM

Making a fixed-wheel bike
 
Following recent bike misadventures, I'm considering taking up a
friend's offer of an old frame, to turn it into a fixed-wheel bike.

He says it's an old touring frame with "relaxed geometry".

My main concern is that the bottom bracket will be too low and I'll keep
catching the pedals on the ground, something that I've done several
times lately on my old Raleigh hybrid.

What else do I need to consider?

I konw it needs to have horizontal drop-outs. What about axle spacing?

Daniele

M-gineering October 19th 07 12:58 PM

Making a fixed-wheel bike
 
D.M. Procida wrote:
Following recent bike misadventures, I'm considering taking up a
friend's offer of an old frame, to turn it into a fixed-wheel bike.

He says it's an old touring frame with "relaxed geometry".

My main concern is that the bottom bracket will be too low and I'll keep
catching the pedals on the ground, something that I've done several
times lately on my old Raleigh hybrid.

What else do I need to consider?

I konw it needs to have horizontal drop-outs. What about axle spacing?

Daniele


consider spd pedals, you'll get cornering clearance, and loosing a pedal
because you forger you were on fixed is much more difficult ;) If you
need conventional pedals fit the thinnest and narrowest you can find.
Shorter cranks or a nice fat tyre will help a lot.
You can bend an old steel frame to any hubwidth you want, but hubs are
available from 110 to 135mm



--
/Marten

info(apestaartje)m-gineering(punt)nl

Arthur Clune October 19th 07 01:35 PM

Making a fixed-wheel bike
 
D.M. Procida wrote:

I konw it needs to have horizontal drop-outs. What about axle spacing?


Not a great problem. If it's an old road frame it'll either be 130mm or
(if very old 125mm), and I'm assuming it's steel.

That gives you two options

1) Buy a rear hub that can be run in 130mm OLN. Easy enough now or
2) Just respace the rear to 120mm and run a track hub. Costs not
a lot if you strip down the bike.

Arthur

--
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


Rob Morley October 19th 07 01:38 PM

Making a fixed-wheel bike
 
In article 1i68e0g.1h02smm1lgpeqgN%[email protected]
juice.co.uk, D.M. Procida
says...
Following recent bike misadventures, I'm considering taking up a
friend's offer of an old frame, to turn it into a fixed-wheel bike.

He says it's an old touring frame with "relaxed geometry".

My main concern is that the bottom bracket will be too low and I'll keep
catching the pedals on the ground, something that I've done several
times lately on my old Raleigh hybrid.


Short cranks with a low Q-factor and small (narrow, shallow) pedals help
improve the clearance. RHS cranks usually stick out further (although
if you're using a double or triple you'll need to fit a shorter axle to
get the chainline correct) and in the UK the road camber means you're
more likely to ground the RHS pedal anyway. :-(

What else do I need to consider?

I konw it needs to have horizontal drop-outs. What about axle spacing?

Horizontal-ish dropouts - you really want at least 1/2 inch of
adjustment to be able to tension the chain properly, although you can
get away with 1/4 inch if you use a half-link in the chain. If it's a
steel frame you can just bend it to suit the hub width - a fixed hub
tends to be 110mm or 120mm OLN, although you can often space it out a
bit especially if it has a solid axle rather than QR (this also gives
some leeway with the chainline adjustment).

Rob Morley October 19th 07 01:57 PM

Making a fixed-wheel bike
 
In article , Arthur Clune
says...
D.M. Procida wrote:

I konw it needs to have horizontal drop-outs. What about axle spacing?


Not a great problem. If it's an old road frame it'll either be 130mm or
(if very old 125mm), and I'm assuming it's steel.

If it's an old road frame it will be 126mm, or 120mm if it's very old.

Duncan Smith October 19th 07 02:02 PM

Making a fixed-wheel bike
 
On Oct 19, 12:47 pm,
(D.M. Procida) wrote:
Following recent bike misadventures, I'm considering taking up a
friend's offer of an old frame, to turn it into a fixed-wheel bike.

He says it's an old touring frame with "relaxed geometry".

My main concern is that the bottom bracket will be too low and I'll keep
catching the pedals on the ground, something that I've done several
times lately on my old Raleigh hybrid.

What else do I need to consider?

I konw it needs to have horizontal drop-outs. What about axle spacing?


You can always fit shorter cranks (160mm?) if you're worried about
pedal strikes. You might be allright with the drop-outs on an older
frame as they tend to be more diagonal than vertical so you could get
enough fore and aft positioning of the wheel to tension the chain - if
not, you could pop on a tensioner like this one:

http://www.on-one.co.uk/index.php?mo... &PAGE_id=140

If you get a flip-flop hub you can run fixed on one side and a
freewheel on the other. Need to decide whether to have 1/8" or a
3/32" chain and cogs (or a mixture of both). Most fixies are 1/8, but
you could run 3/32 just as easy. If the chain is 1/8 you can run both
kinds of cog, but you can't run a 1/8th cog on a 3/32 chain because
the cog will be bigger than the chain.

I'd say it would be easiest to get a track hub, then you may as well
go for a 1/8th setup. Again, 'On-One' do a good wheel build for just
under 100 - pretty good and about a third of the cost of 'top end'
kit.

You'll also something like a Hozan C-205 Lockring spanner
http://www.hubjub.co.uk/etc/etc.htm for keeping the cog on - unless
you never brake by pedaling backwards as pedaling forwards will only
tighten the cog.

HTH,

Duncan


D.M. Procida October 19th 07 02:08 PM

Making a fixed-wheel bike
 
M-gineering wrote:

My main concern is that the bottom bracket will be too low and I'll keep
catching the pedals on the ground, something that I've done several
times lately on my old Raleigh hybrid.

What else do I need to consider?

I konw it needs to have horizontal drop-outs. What about axle spacing?


consider spd pedals, you'll get cornering clearance, and loosing a pedal
because you forger you were on fixed is much more difficult ;) If you
need conventional pedals fit the thinnest and narrowest you can find.
Shorter cranks or a nice fat tyre will help a lot.


Fat tyres, no thanks! But yes, of course I would have SPDs.

You can bend an old steel frame to any hubwidth you want, but hubs are
available from 110 to 135mm


I thought bending was bad for frames, and was not advised. In fact in
the days when six-speed hubs were new, I remember reading strong
warnings not to try forcing them to fit by bending.

Daniele

Rob Morley October 19th 07 02:17 PM

Making a fixed-wheel bike
 
In article 1i68hif.8w2rf2p5k39cN%[email protected]
juice.co.uk, D.M. Procida
says...

I thought bending was bad for frames, and was not advised. In fact in
the days when six-speed hubs were new, I remember reading strong
warnings not to try forcing them to fit by bending.

Not generally a problem with steel (except perhaps for thin heat-treated
stuff like Reynolds 753). What you probably shouldn't do is to spring
the frame to fit a wider hub - this keeps it under constant tension and
may lead to weakening, while if you reset the frame it's a one-off
bending. You also need to make sure that the dropouts are parallel
after you've respaced them - an easy way to do this is to bolt a
(straight) axle into one side so it doesn't quite reach the opposite
dropout, and tweak it until it's pointing in the right direction, then
repeat on the other side. with single speed you obviously don't need to
worry about derailleur hanger alignment.

[email protected] October 19th 07 03:46 PM

Making a fixed-wheel bike
 
On 19 Oct, 14:02, Duncan Smith wrote:
On Oct 19, 12:47 pm,

(D.M. Procida) wrote:
Following recent bike misadventures, I'm considering taking up a
friend's offer of an old frame, to turn it into a fixed-wheel bike.


Yeah, go for it. It's fun.

My main concern is that the bottom bracket will be too low and I'll keep
catching the pedals on the ground, something that I've done several
times lately on my old Raleigh hybrid.


Low profile pedals. I gather you're planning to use those new-fangled
clipless thingies- you should be fine with those as far a clearance
goes (though other fixie riders may laugh at you... or maybe that's
just me :-).

What else do I need to consider?


What gear you want- personally I like a lowish one (~64"), most
people seem to prefer something nearer 70). Cogs are easiest to find
around 15-16t, so if you can get a chainring around 42t that can make
it easier to get a likely gear.

I konw it needs to have horizontal drop-outs. What about axle spacing?


This can usually be fettled fairly easily- if you're using a "track
hub" then you can buy to suit, otherwise you'll probably want to
redish the wheel anyway. A suitable combination of dish, spacers etc
can usually be arrived at.

You can always fit shorter cranks (160mm?) if you're worried about
pedal strikes.


These can be quite hard to find. 165mm "track" chainsets are quite
readily available at a price, standard road ones are usually 170mm and
will probably work fine. 175mm ATB cranks are probably best avoided
for this application...

... You might be allright with the drop-outs on an older
frame as they tend to be more diagonal than vertical so you could get
enough fore and aft positioning of the wheel to tension the chain - if
not, you could pop on a tensioner like this one:

http://www.on-one.co.uk/index.php?mo...E_user_op=view...


NO! Not for a fixie. It'll work on a single-speed (which is what On-
One are listing it for) but won't take the strain from a fixie.

You'll also something like a Hozan C-205 Lockring spannerhttp://www.hubjub.co.uk/etc/etc.htmfor keeping the cog on - unless
you never brake by pedaling backwards as pedaling forwards will only
tighten the cog.


I prefer to use brakes to stop, as a general rule, though I sometimes
skid-stop the last bit to keep the cranks orientated for a good
launch. I, along with many others, havn't had any problems running
without a lockring. One of my fixies has a 22t cog (ie lots of
leverage) without a lockring and it doesn't unscrew. If not running a
back brake it might be worth ensuring you have one but otherwise I
wouldn't sweat it.

Cheers,
W.


Arthur Clune October 19th 07 03:58 PM

Making a fixed-wheel bike
 
Rob Morley wrote:

If it's an old road frame it will be 126mm, or 120mm if it's very old.


Opps. That's what I meant. Sigh.

Arthur

--
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



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