Converting to single speed. A few questions - if you don't mind.



T

TrailRat

Guest
I have an old Raliegh frame lying around which my Father is threating
to chuck out of his garage. I live away from the family nest but store
infrequently used bikes at my parents, no space at mine you see (flat
above a shop). Sorry I waffle. Talking of waffles is Wafflycat still
known as the PSF (Paving Slab Fairy). Sorry I digress.

This frame I want to convert into a cargo carrier. It's a sturdy
enough frame for the job. My plan is to use it to move stuff from A to
B, probably with the aid of a trailer. Because I'm fed of the constant
tinkering with gears I plan to turn this old 24 speed frame into a
single speed fixed bike.

Is it a simple job to do? I'm guessing it is.
What sort of ratios am I looking for, for the job I plan to use it
for? The lay of the land is relativly flat with one or two jobs taking
me into some slightly hilly terrain. But all the riding will be done
on the road, no cycle paths or cross country. I may intend to use it
as a tourer of sorts in the future.

Anything else I should know about making this old mountain bike into
cargo carrier would be helpful.

Thanks.
 
T

Tony Raven

Guest
TrailRat wrote on 13/06/2007 21:16 +0100:
>
> Is it a simple job to do? I'm guessing it is.
>


AUSHTA.
http://sheldonbrown.com/singlespeed.html

--
Tony

"The most savage controversies are those about matters as to which there
is no good evidence either way."
- Bertrand Russell
 
D

Duncan Smith

Guest

> I have an old Raliegh frame lying around which my Father is threating
> to chuck out of his garage. I live away from the family nest but store
> infrequently used bikes at my parents, no space at mine you see (flat
> above a shop). Sorry I waffle. Talking of waffles is Wafflycat still
> known as the PSF (Paving Slab Fairy). Sorry I digress.
>
> This frame I want to convert into a cargo carrier. It's a sturdy
> enough frame for the job. My plan is to use it to move stuff from A to
> B, probably with the aid of a trailer. Because I'm fed of the constant
> tinkering with gears I plan to turn this old 24 speed frame into a
> single speed fixed bike.
>
> Is it a simple job to do? I'm guessing it is.
> What sort of ratios am I looking for, for the job I plan to use it
> for? The lay of the land is relativly flat with one or two jobs taking
> me into some slightly hilly terrain. But all the riding will be done
> on the road, no cycle paths or cross country. I may intend to use it
> as a tourer of sorts in the future.
>
> Anything else I should know about making this old mountain bike into
> cargo carrier would be helpful.
>


Your biggest factor will be the angle of the drop-outs. If they're
more or less vertical then getting a good tension on the chain becomes
more difficult, though use of a half-link for 'magic gear' setups
could help. Alternatively you could use a clip-on chain-tensioner to
take up the slack which should make life easier. If the drop outs are
more obtuse then you have some scope for sliding the wheel back and
forth.

If you're knocking something up on the cheap then you could stay with
3/32 and strip a cassette down to a single cog and pad it out with
spacers to get a straight chain-line - locking it in place with an old
style bottom bracket lock-ring. Or (if it were me) I'd lookout for a
second-hand track hub and go for a 1/8 track cog and chain-ring.

For gear ratios I'd have thought you'd want to start with 66" and be
able to change up to about 70" as you get more comfortable. For 700c
wheels that'd be a 42t chain-ring with 17 and 16t cogs, you'll need to
re-work that a little for 26" wheels - see Sheldon Brown's calculator
for the formulas.

Another useful page is http://www.sheldonbrown.com/fixed.html which
covers converting an MTB there are other on the net if you search
around.

Good luck, hope it goes well for you.

Regards,

Duncan.
 
T

TrailRat

Guest
I don't know if it makes a difference but I'll be using 26" hybrid
road tyre.

As for the dropouts, I'm not too sure what type they are. I'll have a
look tomorrow when I'm round my parents again.

I'll take a picture too, so I can show you if you don't mind.
 
T

TrailRat

Guest
On Jun 13, 10:58 pm, TrailRat <[email protected]> wrote:
> I don't know if it makes a difference but I'll be using 26" hybrid
> road tyre.
>
> As for the dropouts, I'm not too sure what type they are. I'll have a
> look tomorrow when I'm round my parents again.
>
> I'll take a picture too, so I can show you if you don't mind.


On reading Mr (Sheldon) Brown's wonderfully insightful website I now
realize that fixed gear is very different from a single speed. What
would be best for my purpose? A "coaster's" hub or fixed hub? I would
use the old wheels involved and just strip it to one gear but I
destroyed the wheels in a scavenge operation. I would of kept it but
the rim had split.


I hate to be a fuddy duddy but I can't seem to find the calculator
you was on about Duncan or I might be though having a Duh moment.
 
D

Duncan Smith

Guest
>
> > I don't know if it makes a difference but I'll be using 26" hybrid
> > road tyre.

>
> > As for the dropouts, I'm not too sure what type they are. I'll have a
> > look tomorrow when I'm round my parents again.

>
> > I'll take a picture too, so I can show you if you don't mind.

>
> On reading Mr (Sheldon) Brown's wonderfully insightful website I now
> realize that fixed gear is very different from a single speed. What
> would be best for my purpose? A "coaster's" hub or fixed hub? I would
> use the old wheels involved and just strip it to one gear but I
> destroyed the wheels in a scavenge operation. I would of kept it but
> the rim had split.
>
> I hate to be a fuddy duddy but I can't seem to find the calculator
> you was on about Duncan or I might be though having a Duh moment.


No problem, here's the calculator http://sheldonbrown.com/gears/ I
confess to never having used it myself, I just use a spreadsheet (it's
a simple formula):

Gear inches (what the virtual diameter of the wheel would actually be
taking into account the mechanical advantage of the gearing - think of
a big Penny-Farthing wheel) =

Wheel Diameter * (Chain-ring teeth / Cog Teeth)

so 26*(42/16) = 68.25, or 64.23 for a 17t

What you want is a wheel built around a 'track hub'. Track hubs have
two threads, one conventional thread that a cog (fixed or freewheel -
you can change at will) screws onto, and another left-handed thread
the a lock-ring screws onto. The idea being that any backwards
pedaling force you apply through the chain is taken up and just
tightens the lockring, keeping the cog in place rather than un-doing
it. This isn't so important if you've got a freewheel on as pedaling
backwards will just spin the freewheel anyway.

I don't know about 26" wheels (used to 27) but there must be a few
about on e-bay because there are enough single-speed MTBs sold these
days.

http://www.63xc.com/ could be a good site for you too.

Regards,

Duncan.
 
B

bookieb

Guest
On Jun 13, 9:16 pm, TrailRat <[email protected]> wrote:
<snip>
> This frame I want to convert into a cargo carrier. It's a sturdy
> enough frame for the job. My plan is to use it to move stuff from A to
> B, probably with the aid of a trailer. Because I'm fed of the constant
> tinkering with gears I plan to turn this old 24 speed frame into a
> single speed fixed bike.
>


Is it only a frame (ie no wheels)?
If you have to buy wheels, tyres, tubes etc., you could easily spend
enough money on those that you could but somthing complete second hand
instead. If it's just a project for a bit of fun, fair enough, but I'd
price it out carefully before starting.

As this is a 24 speed, it's probably an older MTB or hybrid, with
triple front rings and an 8 speed freehub on the back?

If the slots in the rear dropouts are vertical (or near vertical), or
shorter than about 25mm in length, making this into a fixed wheel bike
is going to be a bit of a PITA. On a fixed wheel bike, the chain
length/tension has to be set pretty much perfectly. Short or vertical
dropouts make this hard to do.
It's not imposible by any means, but will probably require more
messing around and/or purchased bits than would a more suitable
frame.
Frankly, I wouldn't bother - I'd either go single-speed non-fixed
(i.e. you can still freewheel), or I'd forget this frame and start
again.

Also, if this bike is for load hauling (panniers/cargo/trailer etc.),
you might be better off keeping at least some gears and a freewheel.
To simplify things, you could dropp the front deraileur/shifter and
using the middle ring only, but keeping the back changer and gears.
This would remove half the complexity, but keep a reasonable range of
gearing for general purpose use.

If you do want a single speed (non-fixed), the simplest way to do it
is to choose a gear you like, and stop using the shifters.

The second simplest way is to choose a gear you like, remove the front
derailleur, both gear shifters and cables, and lock the rear
derailleur into the gear you want with the limit adjusting screws (you
may need to swap in longer screws to hold it in the gear you want).
The rear derailleur remains in place, and acts as a chain tensioner,
as well as keeping the chain on the selected cog at the back.
You could also remove the unused front chainring(s) (may require
shorter chainring mounting bolts).
Getting this far requires no tools beyond a couple of screwdrivers,
allen keys and a couple of spanners.

You can also remove any unused cogs in the rear cassette (replace the
cogs with spacers) - take the chance to move the remaining cog left or
right so that it's aligned directly behind the remaining front
chainring, and the chain travels in as straight a line as possible.
You'll need a casette removal tool to do this step.

Removing these unused chainrings and cogs is really just for looks and
would also give a minor weight saving, but on a sturdy cargo bike, a
what's half a pound either way?


> Is it a simple job to do? I'm guessing it is.


It's simple enough if you want single-speed non-fixed.
To make a fixie, it's only simple if you've got suitable dropouts and
a freewheel based hub, and even then, it takes a bit more thinking
about and effort than non-fixed.

> What sort of ratios am I looking for, for the job I plan to use it
> for? The lay of the land is relativly flat with one or two jobs taking
> me into some slightly hilly terrain.


A fixed gear of 60" would be the low end, 80" would be high, but if
this is really for load-lugging, I wonder if around 50" might be more
suitable?

>But all the riding will be done
> on the road, no cycle paths or cross country. I may intend to use it
> as a tourer of sorts in the future.
>


Cargo bikes and tourers are two kinds of bike where gears and
freewheels are really helpful.

> Anything else I should know about making this old mountain bike into
> cargo carrier would be helpful.
>
> Thanks.


If you haven't got room to store another bike, you'll have to choose
any trailer you get carefully.
A good rear rack and front rack or front low riders, teamed with
panniers might be worth considering.

hth,

bookieb
 
T

TrailRat

Guest

>
> Is it only a frame (ie no wheels)?
> If you have to buy wheels, tyres, tubes etc., you could easily spend
> enough money on those that you could but somthing complete second hand
> instead. If it's just a project for a bit of fun, fair enough, but I'd
> price it out carefully before starting.


Yes, It's only a frame with one or two useless damaged components,
which have been removed and broken down into spares.
I have no intention buying any spares or parts for this project as I
get pretty much free scavenging rights at my local LBS. I already have
enough bits to build a new rear wheel when I get the hub I decide on
getting. My LBS will tidy that up for me, whilst I make him a cuppa
tea of course.

> If you haven't got room to store another bike, you'll have to choose
> any trailer you get carefully.
> A good rear rack and front rack or front low riders, teamed with
> panniers might be worth considering.


No concerns over storage of the "The Two Wheel Transit" as when its
complete it will be a working bike and "not a pile of junk cluttering
up space" in my Dad's garage. We only live about 2 miles apart and I
can bike over there on my mountain bike, which I'll still use more,
when ever I need to do some serious carting around. Oh, panniers
already bought and paid for. Had them ages but they never really
suited The Gringo.
>
> hth,
>
> bookieb



Thanks for the advice, stored and logged for future reference. Now to
get my tired behind down to the shop.
 
S

Sheldon Brown

Guest

> > On reading Mr (Sheldon) Brown'swonderfully insightful website I now
> > realize that fixed gear is very different from a single speed. What
> > would be best for my purpose? A "coaster's" hub or fixed hub? I would
> > use the old wheels involved and just strip it to one gear but I
> > destroyed the wheels in a scavenge operation. I would of kept it but
> > the rim had split.


Fixed gear is more fun.

> > I hate to be a fuddy duddy but I can't seem to find the calculator
> > you was on about Duncan or I might be though having a Duh moment.

>
> No problem, here's the calculatorhttp://sheldonbrown.com/gears/I
> confess to never having used it myself, I just use a spreadsheet (it's
> a simple formula):


I use that for multispeed calculations. For just one gear, I
generally use one of my trusty slide rules.

http://sheldonbrown.com/sliderule

Sheldon "Slipstick" Brown
+---------------------------------------------------------------+
| Anyone who can't use a slide rule is a cultural illiterate, |
| and should not be allowed to vote. --Robert A. Heinlein |
+---------------------------------------------------------------+