New build...gearing: front fixed 48t and 11-32 9-speed rear. How difficult?

[[email protected]]

Ok, first I've never done any build from scratch. Second how easy is
it to get a fixed 48t front crankset to line up with any 9-speed rear
cog...spacing and what not? What's the math involved? Who ever can
explain in simplest terms wins the "Golden Boot" award.

Randolf

 

[M-gineering]

[email protected] wrote:
> Ok, first I've never done any build from scratch. Second how easy is
> it to get a fixed 48t front crankset to line up with any 9-speed rear
> cog...spacing and what not? What's the math involved? Who ever can
> explain in simplest terms wins the "Golden Boot" award.
>
> Randolf
>

Aim for the middle cog and hope for the best. Single rings with a
chaintensioner have the nasty habit of dropping the chain. Use
cross-rings (old 52's with teeth ground of), an old derailleur or at the
very least a Jumpstop

--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

 

[Dave Reckoning]

M-gineering" <[email protected]> wrote in message
news:[email protected]...
> [email protected] wrote:
>> Ok, first I've never done any build from scratch. Second how easy is
>> it to get a fixed 48t front crankset to line up with any 9-speed rear
>> cog...spacing and what not? What's the math involved? Who ever can
>> explain in simplest terms wins the "Golden Boot" award.
>>
>> Randolf
>>
>
> Aim for the middle cog and hope for the best. Single rings with a
> chaintensioner have the nasty habit of dropping the chain. Use cross-rings
> (old 52's with teeth ground of), an old derailleur or at the very least a
> Jumpstop
>
> --
> ---
> Marten Gerritsen
>
> INFOapestaartjeM-GINEERINGpuntNL
> www.m-gineering.nl

From what I can tell he is talking about a single rear cog on a nine speed
cassette hub. I think this may be a singel speed not a fixed gear.

Dave

 

[[email protected]]

No, what I want is a 48t single chain ring up front...no front
derailure because there would be no derailing to be had in the front.

Then I want a nine speed derailure and nine-speed cog in the rear. The
bike would literally have nine speeds. Not a triple or double...a
single! Though it would not be a true fixed gear cause I'd have nine.
Ideally the front CR would be 48t. The rear would be 11-32 cassette.
There would be NO overlapping gears and honestly all the gears I need
for my commuting.

I wouldn't have to buy a double or triple shifter and front derailure,
but would have to have a brake lever in the front. Just want to build
what I need instead of a triple or double that doesn't do exactly what
I want. Be nice to save money too, but likely not.

Anyone like this idea or is it a waste of time?

Randolf

 

[Booker C. Bense]

-----BEGIN PGP SIGNED MESSAGE-----

In article <[email protected]>,
<[email protected]> wrote:
>No, what I want is a 48t single chain ring up front...no front
>derailure because there would be no derailing to be had in the front.
>
>Then I want a nine speed derailure and nine-speed cog in the rear. The
>bike would literally have nine speeds. Not a triple or double...a
>single! Though it would not be a true fixed gear cause I'd have nine.
>Ideally the front CR would be 48t. The rear would be 11-32 cassette.
>There would be NO overlapping gears and honestly all the gears I need
>for my commuting.
>
>I wouldn't have to buy a double or triple shifter and front derailure,
>but would have to have a brake lever in the front. Just want to build
>what I need instead of a triple or double that doesn't do exactly what
>I want. Be nice to save money too, but likely not.
>
>Anyone like this idea or is it a waste of time?
>

_ I think it's an excellent idea for a commuter. You likely won't
save much if any money unless you've got all the parts handy, but
you aren't the only person thinking this way. A lot of MTB's are
also switching to just a derailler in the back with a 32 or 36
single ring up front.

_ Get a 48t ring w/o shifting ramps and pins and you should be
just fine. Any 3/32 road ring will work just fine with 9spd
chain for this usage. I don't really understand your chainline question,
anywhere vaguely in the middle should be just fine. With
a rear derailler bike, chainline is only an issue if you
want indexed shifting on the front derailler.

_ Booker C. Bense




-----BEGIN PGP SIGNATURE-----
Version: 2.6.2

iQCVAwUBRHOraGTWTAjn5N/lAQFHywP+KRGxjJsMbE+qchgn/bt4E1NUp89OD0eD
ZL7KvOuzor8U2OgHLeRnauIx1WrTAIJTkCczF4s1+k8g0+G1Ws9m1DzMyJjzrm9i
Uc+7KmGLw0YpWzL3wKODpFhFVGHqk8mLh86ZFtY2sOttWE4TS+iR2QyaW881TSBL
1EcEkmGpCHw=
=b6zT
-----END PGP SIGNATURE-----

 

[Barnard Frederick]

[email protected] says...

> Ok, first I've never done any build from scratch. Second how easy is
> it to get a fixed 48t front crankset to line up with any 9-speed rear
> cog...spacing and what not? What's the math involved? Who ever can
> explain in simplest terms wins the "Golden Boot" award.
>
> Randolf

I would think it would be doable. Do you have a crankset picked out?
Does it give you any chainline numbers with a recommended bottom bracket
spindle length? The recommended spindle length may not be what you
need, but it would be a clue and a starting point. Finding the correct
spindle length may be a trial and error process. I would buy the bottom
bracket last after doing some experimenting with the crank placement on
the bike.

 

[[email protected]]

[email protected] wrote:
> No, what I want is a 48t single chain ring up front...no front
> derailure because there would be no derailing to be had in the front.
>
> Then I want a nine speed derailure and nine-speed cog in the rear.
> .....
> Anyone like this idea or is it a waste of time?
>
Not a waste of time. It might make a neat bike.

Regarding chainline, on a conventional crankset you can adjust
chainlines by choosing the inner or outer chainring position. Also,
some chainrings are not symetrical so small adjustments can be made by
flipping them over.

Chainline can also be altered in front by different bottom bracket
lengths. Also, small adjustments can be made by placing 1 mm spacers
between one BB cup and the shell.

In the back, chainline can be adjusted by moving spacers on the rear
axle and re-dishing the wheel.

The overall goal, as others have mentioned, is to line up the 48t
chainring with the middle cog of your cassette.

Once you've done that, you may find that when you are in the smallest
or largest cassette cog your chainline is far enough off that you are
dropping your chain. A cheap solution is to fix a front derailleur to
act as a chain keeper.

Good luck,
Tom

 

[M-gineering]

Dave Reckoning wrote:
> M-gineering" <[email protected]> wrote in message
> news:[email protected]...
>> [email protected] wrote:
>>> Ok, first I've never done any build from scratch. Second how easy is
>>> it to get a fixed 48t front crankset to line up with any 9-speed rear
>>> cog...spacing and what not? What's the math involved? Who ever can
>>> explain in simplest terms wins the "Golden Boot" award.
>>>
>>> Randolf
>>>
>> Aim for the middle cog and hope for the best. Single rings with a
>> chaintensioner have the nasty habit of dropping the chain. Use cross-rings
>> (old 52's with teeth ground of), an old derailleur or at the very least a
>> Jumpstop
>>
>> --
>> ---
>> Marten Gerritsen

>
> From what I can tell he is talking about a single rear cog on a nine speed
> cassette hub. I think this may be a singel speed not a fixed gear.
>
> Dave
>
>

Wrong.
If you have a single chainring, and the possibility for the chain to get
slack (ie a chaintensioner) a bump in the road could set of a horizontal
wave in the chain which will derail it.
--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

 

[Qui si parla Campagnolo]

[email protected] wrote:
> Ok, first I've never done any build from scratch. Second how easy is
> it to get a fixed 48t front crankset to line up with any 9-speed rear
> cog...spacing and what not? What's the math involved? Who ever can
> explain in simplest terms wins the "Golden Boot" award.
>
> Randolf

Line up the front ring with the center of the cogset. That line should
be parallel to the top tube. Use single chainring bolts and BB length
combo to get the above.

Be sure you use something to keep the chain on the front single ring. A
friont der or chainguide or outside guide and chainwatcher on the
inside, something, or it will fall off.

 

[Qui si parla Campagnolo]

Dave Reckoning wrote:
> M-gineering" <[email protected]> wrote in message
> news:[email protected]...
> > [email protected] wrote:
> >> Ok, first I've never done any build from scratch. Second how easy is
> >> it to get a fixed 48t front crankset to line up with any 9-speed rear
> >> cog...spacing and what not? What's the math involved? Who ever can
> >> explain in simplest terms wins the "Golden Boot" award.
> >>
> >> Randolf
> >>
> >
> > Aim for the middle cog and hope for the best. Single rings with a
> > chaintensioner have the nasty habit of dropping the chain. Use cross-rings
> > (old 52's with teeth ground of), an old derailleur or at the very least a
> > Jumpstop
> >
> > --
> > ---
> > Marten Gerritsen
> >
> > INFOapestaartjeM-GINEERINGpuntNL
> > www.m-gineering.nl
>
> From what I can tell he is talking about a single rear cog on a nine speed
> cassette hub. I think this may be a singel speed not a fixed gear.
>
> Dave

I guess it's not math involved but english...single cog in the back?
what are ya trying to do? 48t front, single in back? horizontal
dropouts or chain tensioner?

 

[Snortley]

I've got a single 44 on the front, and 11-34 x 9 on the back,
with the ring in line with the center cog, and yup, the chain came
off. I put a DMR chain cage on at the ring, which took a lot of
tweaking, not to mention a lot of cussing and spitting, and now the
chain stays on.




You got to be very careful if you don't know where you're going, because you might not get there.


- Yogi Berra

 

[Peter Cole]

[email protected] wrote:
> No, what I want is a 48t single chain ring up front...no front
> derailure because there would be no derailing to be had in the front.
>
> Then I want a nine speed derailure and nine-speed cog in the rear. The
> bike would literally have nine speeds. Not a triple or double...a
> single! Though it would not be a true fixed gear cause I'd have nine.
> Ideally the front CR would be 48t. The rear would be 11-32 cassette.
> There would be NO overlapping gears and honestly all the gears I need
> for my commuting.
>
> I wouldn't have to buy a double or triple shifter and front derailure,
> but would have to have a brake lever in the front. Just want to build
> what I need instead of a triple or double that doesn't do exactly what
> I want. Be nice to save money too, but likely not.
>
> Anyone like this idea or is it a waste of time?
>
> Randolf
>

Kind of a waste of time. You need something to keep the chain on, and
front derailers are about the cheapest/lightest. Double cranks are the
most common, so you'll likely just buy that & throw a ring away. Might
as well put at least a left DT shifter on.

 

[[email protected]]

I'd have to agree and I'm the OP. Time and money spent it would be
wiser to just buy a double.

Randolf

 

[Jasper Janssen]

On Tue, 23 May 2006 17:14:30 +0200, M-gineering
<[email protected]> wrote:

>Aim for the middle cog and hope for the best. Single rings with a
>chaintensioner have the nasty habit of dropping the chain. Use
>cross-rings (old 52's with teeth ground of), an old derailleur or at the
>very least a Jumpstop

Why does grinding teeth off help with not dropping the chain?

Jasper

 

[dvt]

Jasper Janssen wrote:
> On Tue, 23 May 2006 17:14:30 +0200, M-gineering
> <[email protected]> wrote:
>
>> Aim for the middle cog and hope for the best. Single rings with a
>> chaintensioner have the nasty habit of dropping the chain. Use
>> cross-rings (old 52's with teeth ground of), an old derailleur or at the
>> very least a Jumpstop
>
> Why does grinding teeth off help with not dropping the chain?

You mount a toothless ring on either side the 48t ring.

--
Dave
dvt at psu dot edu

 

[Josh Hassol]

[email protected] wrote:
> No, what I want is a 48t single chain ring up front...no front
> derailure because there would be no derailing to be had in the front.
>
> Then I want a nine speed derailure and nine-speed cog in the rear. The
> bike would literally have nine speeds. Not a triple or double...a
> single! Though it would not be a true fixed gear cause I'd have nine.
> Ideally the front CR would be 48t. The rear would be 11-32 cassette.
> There would be NO overlapping gears and honestly all the gears I need
> for my commuting.
>

This sounds almost exactly like my bike, which is also a commuter. I
have a smaller single ring up front (42t, I need to get a larger ring),
and a 9-speed Ultegra cassette on the back, using a 105 short-cage
derailleur. Works great generally (notwithstanding the strange
shifting problem I posted about today). I've _never_ had the chain
drop.

- Josh

 

[Jasper Janssen]

On Thu, 25 May 2006 15:22:33 -0400, dvt <[email protected]> wrote:
>Jasper Janssen wrote:
>> On Tue, 23 May 2006 17:14:30 +0200, M-gineering
>> <[email protected]> wrote:
>>
>>> Aim for the middle cog and hope for the best. Single rings with a
>>> chaintensioner have the nasty habit of dropping the chain. Use
>>> cross-rings (old 52's with teeth ground of), an old derailleur or at the
>>> very least a Jumpstop
>>
>> Why does grinding teeth off help with not dropping the chain?
>
>You mount a toothless ring on either side the 48t ring.

Ah, one of those thingies. Now it makes sense.

Jasper