Shimano 105 half step?

angus said:

My current crankset is a Shimano 105 triple, 52-42-30 (130/74 BCD). I
want to switch to half step gearing, namely 52-48-30.

Are there any compatible 48 tooth middle rings available anywhere? So
far neither my LBS nor google have been of any help.

TA make 130 mm BCD rings in 38-57 tooth sizes. They don't have the huge
ramps that Shimano rings do, but the shift from a 24 to a 42 seems to work
OK.

--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
We had that Maurits C. Escher in to do some building work once. I
haven't been able to leave the house since.

angus said:

My current crankset is a Shimano 105 triple, 52-42-30 (130/74 BCD). I
want to switch to half step gearing, namely 52-48-30.

Are there any compatible 48 tooth middle rings available anywhere? So
far neither my LBS nor google have been of any help.

Note that the Shimano triple derailleur will not work

--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl

angus said:

Are there any compatible 48 tooth middle rings available anywhere? So
far neither my LBS nor google have been of any help.

When you find the ring, and it exists, you'll need to find a front
derailleur that will shift 52/48. You may have to get a 46 or 54t
ring.

angus said:

My current crankset is a Shimano 105 triple, 52-42-30 (130/74 BCD). I
want to switch to half step gearing, namely 52-48-30.

Are there any compatible 48 tooth middle rings available anywhere? So
far neither my LBS nor google have been of any help.

Cheers,
Angus

Perhaps try http://www.gebhardt.cz/ . I can't get through to the
English-speakers' pages to check (no pun intended) but I have bought a
62T chainring so I know that they do odd sizes and custom rings. The
product is good, perhaps this will do?

m-gineering said:

Note that the Shimano triple derailleur will not work

Paul Kopit said:

When you find the ring, and it exists, you'll need to find a front
derailleur that will shift 52/48. You may have to get a 46 or 54t
ring.

Hmm, an unanticipated glitch in my plans. Can anyone explain why the
Shimano derailleur will have problems shifting between 52 and 48?

And perhaps suggest a more suitable derailleur?

Cheers,
Angus

angus said:

m-gineering said:

Note that the Shimano triple derailleur will not work

Paul Kopit said:

When you find the ring, and it exists, you'll need to find a front
derailleur that will shift 52/48. You may have to get a 46 or 54t
ring.

Hmm, an unanticipated glitch in my plans. Can anyone explain why the

Quoted message said:

Shimano derailleur will have problems shifting between 52 and 48?

And perhaps suggest a more suitable derailleur?

As others have said, TA makes all sizes of chainrings in the 130mm bcd
pattern. Peter White Cycles sells them. Some of the rings have shift
assist ramps and others do not. Depends on the number of teeth.

As for your choice of 52-48-30, why? Are you trying to emulate Jobst
Brandt with extremely high gearing? I've found very, very few people
who need two big chainrings on the same bike. I currently have
45-42-20 chainrings on my touring bike. Had 48-45-20 rings. Another
half step possibility is 42-39-20. Paired up with a 9 speed Shimano
12-14-16-18-20-23-26-30-34 cassette you have very nice half step
gearing. And you can easily replace the 30 inner ring with a 24 so you
have a real granny gear.

On my touring bike I use a Sora double front derailleur. The problem
with using a triple front derailleur is that the deep back cage hits
the middle ring unless the derailleur is positioned very high on the
seattube. The Shimano triple front derailleur will shift between the
48 and 52 just fine. Having the front derailleur mounted high on the
seattube does not affect shifting. I used such a setup for many years.
But having the front derailleur mounted high means the chain will rub
on the bottom of the cage when trying to use the smaller cogs in back.
Not a big problem, but noisy.

angus said:

m-gineering said:

Note that the Shimano triple derailleur will not work

Paul Kopit said:

When you find the ring, and it exists, you'll need to find a front
derailleur that will shift 52/48. You may have to get a 46 or 54t
ring.

Hmm, an unanticipated glitch in my plans. Can anyone explain why the
Shimano derailleur will have problems shifting between 52 and 48?

I'm pretty sure that it's because the shifting indentations on the outer
part of the derailleur cage won't match up with where the chain will be if
it were on the 48t cog. The case may be the same for inner cage, too. If
you want to hack-job it, you can bend the derailleur cage so that it will
push the chain around, but derailleur cages are really difficult to bend
around the axis of the bike's direction of travel, so unless you have a good
set of clamps and whatnot, it'll be better to look for another derailleur.

--
Phil, Squid-in-Training

[email hidden] wrote:

some text snipped . . .

Quoted message said:

As for your choice of 52-48-30, why? Are you trying to emulate Jobst
Brandt with extremely high gearing?

At first glance it looks like tall gearing but since this bike has 20"
wheels (which I had failed to mention before), some might claim that
it's geared a little too *low*. But it suits me fine. I'm not a racer,
just a tourer.

Quoted message said:

I've found very, very few people
who need two big chainrings on the same bike. I currently have
45-42-20 chainrings on my touring bike. Had 48-45-20 rings. Another
half step possibility is 42-39-20.

Yes that's the type of gearing I'm trying to emulate, without busting
the bank with another entire crank set. I used 44-40-24 for many years
on my old 27" and 700c touring bikes with great success.

Cheers,
Angus

Comments at bottom.

Phil said:

angus said:

m-gineering said:

Note that the Shimano triple derailleur will not work

Paul Kopit said:

When you find the ring, and it exists, you'll need to find a front
derailleur that will shift 52/48. You may have to get a 46 or 54t
ring.

Hmm, an unanticipated glitch in my plans. Can anyone explain why

the

Quoted message said:

Quoted message said:

Shimano derailleur will have problems shifting between 52 and 48?

I'm pretty sure that it's because the shifting indentations on the

outer

Quoted message said:

part of the derailleur cage won't match up with where the chain will

be if

Quoted message said:

it were on the 48t cog. The case may be the same for inner cage,

too. If

Quoted message said:

you want to hack-job it, you can bend the derailleur cage so that it

will

Quoted message said:

push the chain around, but derailleur cages are really difficult to

bend

Quoted message said:

around the axis of the bike's direction of travel, so unless you have

a good

Quoted message said:

set of clamps and whatnot, it'll be better to look for another

derailleur.

Quoted message said:

--
Phil, Squid-in-Training

Uh, no- the current crop of Shimano "road triple" front derailleurs
have a very deep inner cage plate. This will run into the middle
chainring of a half-step-plus-granny arrangement when you try to shift
to the outer ring. You need a derailluer that will clear the middle
ring when the chain is on the outer ring, yet have a long enough cage
to shift to the inner ring.

Shimano *did* make a half-step version of the Deore and Deore XT (and
Deore II and Deore XT II) front derailleurs back in the 1987-89
timeframe. (There was also an "alpine version":
http://www.firstflightbikes.com/shimano.htm .) This *should* work, but
there's no guarantees. You'll have to find one and give it a try.

FWIW: FSA makes odder-size chainrings with pins and ramps to fit your
crank:
the largest "middle triple" is a 44-tooth:
http://www.biketoolsetc.com/index.cgi?&d=single&item_id=FS-RR44M
but there's also an outer 48-tooth that might work in the middle:
http://www.biketoolsetc.com/index.cgi?&d=single&item_id=FS-RR48AG

Jeff

Paul Kopit said:

Quoted message said:

When you find the ring, and it exists, you'll need to find a front
derailleur that will shift 52/48. You may have to get a 46 or 54t
ring.

Marten said:

Quoted message said:

Note that the Shimano triple derailleur will not work

Angus said:

Hmm, an unanticipated glitch in my plans. Can anyone explain why the
Shimano derailleur will have problems shifting between 52 and 48?

And perhaps suggest a more suitable derailleur?

The inner cage plate of a "triple" front derailer hangs down too low, it
would bump into the 48 tooth ring as you tried to shift to the 52.

For those who like the atavistic half-step-plus-granny system, modern
derailers designated as "doubles" are the way to go.

Sheldon "Hates Half Step But Wants To Be Helpful Anyway" Brown
+------------------------------------------------------+
| It were not best that we should all think alike; |
| it is difference of opinion that makes horse-races. |
| -- Mark Twain |
+------------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

Sheldon Brown said:

Sheldon "Hates Half Step But Wants To Be Helpful Anyway" Brown

OK, then do the two-step:
http://www.janbrett.com/piggybacks/step.htm

Jeff

Quoted message said:

Quoted message said:

I've found very, very few people
who need two big chainrings on the same bike. I currently have
45-42-20 chainrings on my touring bike. Had 48-45-20 rings. Another
half step possibility is 42-39-20.

Yes that's the type of gearing I'm trying to emulate, without busting the
bank with another entire crank set. I used 44-40-24 for many years on my
old 27" and 700c touring bikes with great success.

But, with 7, 8 or even 9 rear cogs, you no longer need to have half-step
gearing to get the gears you might need for any particular use. Back in the
days, when we only had 5, possibly 6 cogs, we had to try and make every one
count. Half-step was an easy way to do that, as shifting between the larger
two chainrings produced a difference of half that of shifting the rear. We
knew where each next lower gear was, eliminating the need for gear charts.

But with 7, 8 or 9 cogs, that's no longer necessary. You can establish what
I call "range" gearing, determined by the front chainring you're in. You've
got your "go fast" gears on the largest chainring, your "normal" gears in
the middle and your "climbing steep stuff" on the smallest. With 7, 8 or 9
cogs, you can have a wide range on each one, without big jumps, and still
have some overlap between the gears found on each chainring (so you don't
have to shift the front nearly as often).

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

"angus" <[email hidden]> wrote in message
news:fqLie.1408925$6l.258114@pd7tw2no...

Quoted message said:

[email hidden] wrote:

some text snipped . . .

Quoted message said:

As for your choice of 52-48-30, why? Are you trying to emulate Jobst
Brandt with extremely high gearing?

At first glance it looks like tall gearing but since this bike has 20"
wheels (which I had failed to mention before), some might claim that it's
geared a little too *low*. But it suits me fine. I'm not a racer, just a
tourer.

Quoted message said:

I've found very, very few people
who need two big chainrings on the same bike. I currently have
45-42-20 chainrings on my touring bike. Had 48-45-20 rings. Another
half step possibility is 42-39-20.

Yes that's the type of gearing I'm trying to emulate, without busting the
bank with another entire crank set. I used 44-40-24 for many years on my
old 27" and 700c touring bikes with great success.

Cheers,
Angus

Mike Jacoubowsky said:

But, with 7, 8 or even 9 rear cogs, you no longer need to have

half-step

Quoted message said:

gearing to get the gears you might need for any particular use.

But with 7, 8 or 9 cogs, that's no longer necessary. You can

establish what

Quoted message said:

I call "range" gearing, determined by the front chainring you're in.

You've

Quoted message said:

got your "go fast" gears on the largest chainring, your "normal"

gears in

Quoted message said:

the middle and your "climbing steep stuff" on the smallest. With 7, 8

or 9

Quoted message said:

cogs, you can have a wide range on each one, without big jumps,

When was the last time you actually toured with panniers front and back
and the rack loaded with tent, sleeping bag, etc. and maybe a handlebar
bag too? "big jumps" with a loaded touring bike into a headwind are
very different from "big jumps" on a racing bike.

Shimano and others make 12-34, 11-34, and 11-32 9 speed cassettes. All
of these have 2-3 tooth jumps between cogs. 11-13-15-17-19- or
12-14-16-18-20- etc. On my racing bike I consider a 2 tooth jump in
gears a "big jump" when in the smaller toothed cogs. On a loaded
touring bike a 2 tooth jump in cogs, a full step in half step gearing,
is very, very big.

Your concept of "range" gearing works OK for unloaded bikes where you
can just put a bit more muscle into the pedaling or if you have 1 tooth
jumps in cogs. But with loaded touring bikes you don't just put a bit
more muscle into a bike with 50 pounds of bags on it. Or pulling a 60
pound BOB trailer. And with loaded touring you need to have a cassette
going from 14 on the small side to 32 on the big side to get the range
of gearing necessary for mountains. So you have to have 2-3-4 tooth
jumps between cogs. Unlike racing bikes that can use straight blocks
from 13 through 19 and have no "big jumps" between gears.

The only way your "range" gearing would work for loaded touring is with
a cassette that goes 14-15-16-17-18-19-21-23-26-30-34. Unfortunately
that is 11 cogs and nobody has gotten that many onto a cassette yet.

Quoted message said:

When was the last time you actually toured with panniers front and back
and the rack loaded with tent, sleeping bag, etc. and maybe a handlebar
bag too? "big jumps" with a loaded touring bike into a headwind are
very different from "big jumps" on a racing bike.

Your experience is different from mine. I find that, when I'm riding a
heavily-loaded bike, I'm much *less* picky about having an exact gear,
whether we're talking about riding into a headwind or a nasty climb. That
includes experience riding with kid trailers (loaded). On my racing bike, on
the other hand, I'm often thinking (ok, making excuses) that, if I had just
a bit lower gear, something in-between, life would be better.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Mike Jacoubowsky said:

But, with 7, 8 or even 9 rear cogs, you no longer need to have

half-step

Quoted message said:

gearing to get the gears you might need for any particular use.

But with 7, 8 or 9 cogs, that's no longer necessary. You can

establish what

Quoted message said:

I call "range" gearing, determined by the front chainring you're in.

You've

Quoted message said:

got your "go fast" gears on the largest chainring, your "normal"

gears in

Quoted message said:

the middle and your "climbing steep stuff" on the smallest. With 7, 8

or 9

Quoted message said:

cogs, you can have a wide range on each one, without big jumps,

When was the last time you actually toured with panniers front and back
and the rack loaded with tent, sleeping bag, etc. and maybe a handlebar
bag too? "big jumps" with a loaded touring bike into a headwind are
very different from "big jumps" on a racing bike.

Shimano and others make 12-34, 11-34, and 11-32 9 speed cassettes. All
of these have 2-3 tooth jumps between cogs. 11-13-15-17-19- or
12-14-16-18-20- etc. On my racing bike I consider a 2 tooth jump in
gears a "big jump" when in the smaller toothed cogs. On a loaded
touring bike a 2 tooth jump in cogs, a full step in half step gearing,
is very, very big.

Your concept of "range" gearing works OK for unloaded bikes where you
can just put a bit more muscle into the pedaling or if you have 1 tooth
jumps in cogs. But with loaded touring bikes you don't just put a bit
more muscle into a bike with 50 pounds of bags on it. Or pulling a 60
pound BOB trailer. And with loaded touring you need to have a cassette
going from 14 on the small side to 32 on the big side to get the range
of gearing necessary for mountains. So you have to have 2-3-4 tooth
jumps between cogs. Unlike racing bikes that can use straight blocks
from 13 through 19 and have no "big jumps" between gears.

The only way your "range" gearing would work for loaded touring is with
a cassette that goes 14-15-16-17-18-19-21-23-26-30-34. Unfortunately
that is 11 cogs and nobody has gotten that many onto a cassette yet.

angus said:

My current crankset is a Shimano 105 triple, 52-42-30 (130/74 BCD). I
want to switch to half step gearing, namely 52-48-30.

Are there any compatible 48 tooth middle rings available anywhere? So
far neither my LBS nor google have been of any help.

Cheers,
Angus

To summarise:
* several people provided sources for 48T-130 bcd rings.
* the standard Shimano triple front derailleur must be replaced with a
double.
* there were suggestions that half step gearing has become obsolete
since the introduction of the 9 speed cassette.

To follow up on the latter I took a look at a couple of the cassettes on
Sheldon's site, namely the Classic 9 and the Ultegra 9.

My current gearing has 52-42-30 front and 11-12-14-16-18-21-24-28-32
rear, giving a gear range of 18.8" to 94.5" with 20" wheels. Although
this is a useful range for me the average jump is an unacceptable 13%.

Sheldon's Classic 9 was the first close-ratio cassette I looked at. It
has cogs of 13-14-15-16-17-18-19-21-24, giving a range of 25.0" to 80.0"
and an average jump of 6.9%. That gives a top speed of 34 km/h at 90
rpm, which is quite acceptable for touring, but 25" would be too hard on
my knees on long climbs. I could replace the granny with a 24T to get a
bottom of 20", but that would leave an unacceptable zero overlap between
the granny range and the middle range.

So the next one I considered was Ultegra 9, which is
12-13-14-15-17-19-24-27. This one has an acceptable range of 22.2" to
86.7". The jumps are a nice 7-8% between the top four cogs but are in
the 12% range between the lower gears, namely just the gears I'd use
most often for loaded touring.

After examining these numbers, half step gearing still looks pretty
good. The gear range would be unchanged from my current range of 18.8"
to 94.5". Each single shift is only 8% and the double shifts are a very
nice 1%-7%-5%-4%-7%-5%-7%-5%. I can still install my 24T granny for
climbing walls. Plus the cost would be $60 for the new chainring and
derailleur, versus $79.95 for a new cassette.

The only downside I see for the half step gearing right now is possible
dodgey shifting to and from the granny, but I'll cross that bridge when
the time comes.

Thanks for all the help.

Cheers,
Angus

Quoted message said:

When was the last time you actually toured with panniers front and back
and the rack loaded with tent, sleeping bag, etc. and maybe a handlebar
bag too? "big jumps" with a loaded touring bike into a headwind are
very different from "big jumps" on a racing bike.

Heh. For me, it was 1986. This was back when 5 speed gearing was still
common and 6 speed was all new fangled. Now my spiffy 7 speed bike is
woefully under geared!!

I think one of the things to remember is that as the number of gears in the
rear goes up from 5 to 6 to 7 to 8 to 9, the size of the tooth jump of the
chain rings in a half-step rig goes down from 5 to 4 to 3.

Putting this another way, while I agree with you that half-step gearing
gives better selection and this selection is more helpful for touring than
for unloaded riding (folks who haven't done it won't get that), at some
point I think diminishing returns kicks in.

Putting still another way, range or alpine geared set ups using a 8 or 9
speed rear end would give something pretty close to the selection that I
had with my old 6 speed half step rig. And we considered it *luxury*!!

(did I mention that we slept in a cardboard box?)

-Dave

pinnah said:

I think one of the things to remember is that as the number of gears in the
rear goes up from 5 to 6 to 7 to 8 to 9, the size of the tooth jump of the
chain rings in a half-step rig goes down from 5 to 4 to 3.

No. Look at current 7, 8, 9 speed cassettes. My 7 speed cassette used
for half step gearing is 14-16-18-21-24-28-32. Chainrings are
45-42-20. For 8 speed cassettes, 12-14-16-18-21-24-28-32 is available
and the right tooth jumps. You notice that the jump in teeth is the
exact same except a 12 was added at the high end. And for 9 speed
Shimano makes a 12-14-16-18-20-23-26-30-34. Again, almost all have the
exact same teeth as the 7 or 8 speed cassettes. You get an extra
smaller step or two at the upper end is all with 9 speed.

Half step gearing works equally well with 7, 8, or 9 speed cassettes
because they all use the same cog teeth.

Quoted message said:

Half step gearing works equally well with 7, 8, or 9 speed cassettes
because they all use the same cog teeth.

Unfortunately, half-step shifts progressively worse as the chain gets
narrower. Its biggest shifting issue is a tendancy for the chain to want to
fall in-between the two largest chainrings, since their spacing (distance
between them) assumes a conventional (10t or greater) difference in
chainring size. As the chainrings get closer in size, the chain is
increasingly-likely to try and fall in-between them (or ride across the top
of the smaller one). The narrower the chain, the greater the issue.

Back in the day, when I was a half-step afficianado, I used to machine down
the part of the crank spider where the chainrings mounted, which resulted in
dramatically-improved shifting. If you wish to try this, make sure you
remove material on the *outside* face, since otherwise you might create too
large a gap for the middle-small shift (on a half-step plus granny).

--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
Redwood City & Los Altos, CA USA

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

pinnah said:

I think one of the things to remember is that as the number of gears in
the
rear goes up from 5 to 6 to 7 to 8 to 9, the size of the tooth jump of
the
chain rings in a half-step rig goes down from 5 to 4 to 3.

No. Look at current 7, 8, 9 speed cassettes. My 7 speed cassette used
for half step gearing is 14-16-18-21-24-28-32. Chainrings are
45-42-20. For 8 speed cassettes, 12-14-16-18-21-24-28-32 is available
and the right tooth jumps. You notice that the jump in teeth is the
exact same except a 12 was added at the high end. And for 9 speed
Shimano makes a 12-14-16-18-20-23-26-30-34. Again, almost all have the
exact same teeth as the 7 or 8 speed cassettes. You get an extra
smaller step or two at the upper end is all with 9 speed.

Half step gearing works equally well with 7, 8, or 9 speed cassettes
because they all use the same cog teeth.

Mike Jacoubowsky said:

Back in the day, when I was a half-step afficianado, I used to machine down
the part of the crank spider where the chainrings mounted, which resulted in
dramatically-improved shifting. If you wish to try this, make sure you
remove material on the *outside* face, since otherwise you might create too
large a gap for the middle-small shift (on a half-step plus granny).

Hi Mike,

Smart solution. Do you recall how much metal you had to take off, or
would this be more of a trial and error process?

Cheers,
Angus