Gearing to high?

Before I start, I realise this is very subjective, but here goes.

Surly Karate Monkey frame, with a Rohloff on 700c wheels (yeah, so shoot
me), gives a gearing of this;

Front 48T
Rear 16T
Wheel D 69cm[1]

Gear Ratio Gearing cms
1 0.28 181.44
2 0.32 205.50
3 0.36 234.11
4 0.41 265.98
5 0.46 301.74
6 0.53 343.36
7 0.60 390.19
8 0.68 443.51
9 0.77 503.34
10 0.88 572.92
11 1.00 650.31
12 1.14 738.10
13 1.29 840.20
14 1.47 954.00

Bike used for a bit of cinder tracking and the odd hill. Normal riding
uses mostly gear 7/8. Hills require 1-3. I rarely use more than 11,
*never* the top gear.

I'm going to change that 48 for a 42, anyone any comments or think this
is a widely high gearing I have?

[1] No, I didn't chalk the tyres, but a 90kg lump on it and carefully
push it over smooth tarmac. I took a tape measure from edge-to-edge and
this is about it!

in message , Tosspot
') wrote:

Before I start, I realise this is very subjective, but here goes.

Surly Karate Monkey frame, with a Rohloff on 700c wheels (yeah, so shoot
me), gives a gearing of this;

Front 48T
Rear 16T
Wheel D 69cm[1]

Gear Ratio Gearing cms
1 0.28 181.44
2 0.32 205.50
3 0.36 234.11
4 0.41 265.98
5 0.46 301.74
6 0.53 343.36
7 0.60 390.19
8 0.68 443.51
9 0.77 503.34
10 0.88 572.92
11 1.00 650.31
12 1.14 738.10
13 1.29 840.20
14 1.47 954.00

Bike used for a bit of cinder tracking and the odd hill. Normal riding
uses mostly gear 7/8. Hills require 1-3. I rarely use more than 11,
*never* the top gear.

I'm going to change that 48 for a 42, anyone any comments or think this
is a widely high gearing I have?

If your figures are correct, your gearing currently has a low gear close to
the highest gear of a standard racing road bike setup, and a high gear
more than three times as high as the highest gear on a standard road
racing setup. However, Sheldon Brown says you're wrong:
http://www.sheldonbrown.com/gears/internal.html

He says your top gear is currently 297cm (116 inches) and your bottom
currently 56.89cm (22.5 inches). These are still definitely in the racing
range; changing to a 42 tooth chainring would give you a range from 50cm
(19.6 inches) to 261.62 cm (103 inches) which is more similar to a normal
mountain bike range.

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

;; Quidquid latine dictum sit, altum sonatur.

Simon Brooke wrote:

in message , Tosspot
') wrote:

Before I start, I realise this is very subjective, but here goes.

Surly Karate Monkey frame, with a Rohloff on 700c wheels (yeah, so shoot
me), gives a gearing of this;

Front 48T
Rear 16T
Wheel D 69cm[1]

Gear Ratio Gearing cms
1 0.28 181.44
2 0.32 205.50
3 0.36 234.11
4 0.41 265.98
5 0.46 301.74
6 0.53 343.36
7 0.60 390.19
8 0.68 443.51
9 0.77 503.34
10 0.88 572.92
11 1.00 650.31
12 1.14 738.10
13 1.29 840.20
14 1.47 954.00

Bike used for a bit of cinder tracking and the odd hill. Normal riding
uses mostly gear 7/8. Hills require 1-3. I rarely use more than 11,
*never* the top gear.

I'm going to change that 48 for a 42, anyone any comments or think this
is a widely high gearing I have?

If your figures are correct, your gearing currently has a low gear close to
the highest gear of a standard racing road bike setup, and a high gear
more than three times as high as the highest gear on a standard road
racing setup. However, Sheldon Brown says you're wrong:
http://www.sheldonbrown.com/gears/internal.html

He says your top gear is currently 297cm (116 inches) and your bottom
currently 56.89cm (22.5 inches). These are still definitely in the racing
range; changing to a 42 tooth chainring would give you a range from 50cm
(19.6 inches) to 261.62 cm (103 inches) which is more similar to a normal
mountain bike range.

It depends on how the gearing is expressed. Metric gear sizes are
usually metres development so straight conversion doesn't equate to
gear inches which is the equivalent diameter of wheel.

Putting 48 and 42 chainrings into Sheldon's calulator with atypical
700C wheel gives:

For 700 X 32 / 32-622 tire and 16 tooth sprocket
48 / 16 42 / 16
1.467 9.5 8.3
13.5 %
1.292 8.4 7.3
13.8 %
1.135 7.4 6.4
13.5 %
1 6.5 5.7
13.5 %
..881 5.7 5.0
13.8 %
..774 5.0 4.4
13.5 %
..682 4.4 3.9
13.7 %
..600 3.9 3.4
13.6 %
..528 3.4 3.0
13.8 %
..464 3.0 2.6
13.4 %
..409 2.7 2.3
13.6 %
..360 2.3 2.0
13.9 %
..316 2.0 1.8
13.3 %
..279 1.8 1.6
With Rohloff Speedhub 14-speed Hub

Or in gear inches

For 700 X 32 / 32-622 tire and 16 tooth sprocket
48 / 16 42 / 16
1.467 118.8 104.0
13.5 %
1.292 104.7 91.6
13.8 %
1.135 91.9 80.4
13.5 %
1 81.0 70.9
13.5 %
..881 71.4 62.4
13.8 %
..774 62.7 54.9
13.5 %
..682 55.2 48.3
13.7 %
..600 48.6 42.5
13.6 %
..528 42.8 37.4
13.8 %
..464 37.6 32.9
13.4 %
..409 33.1 29.0
13.6 %
..360 29.2 25.5
13.9 %
..316 25.6 22.4
13.3 %
..279 22.6 19.8
With Rohloff Speedhub 14-speed Hub

I would say that the 48 is a little overgeared. Dropping to a 42 is
the quivalent of dropping a gear step and looks eminently sensible to
me with a top gear equivalent to something between 52x13/14 which you
are only ever going to use when going downhill or with a srong wind
behind you. I can't imagine ever using the top gear provided by the 48
tooth ring.
--
Phil Cook looking north over the park to the "Westminster Gasworks"

In article , Simon
Brooke
says...

If your figures are correct, your gearing currently has a low gear close to
the highest gear of a standard racing road bike setup, and a high gear
more than three times as high as the highest gear on a standard road
racing setup.

I think perhaps you left Pi out of the equation. :-)

Simon Brooke wrote:
in message , Tosspot
') wrote:


Before I start, I realise this is very subjective, but here goes.

Surly Karate Monkey frame, with a Rohloff on 700c wheels (yeah, so shoot
me), gives a gearing of this;

Front 48T
Rear 16T
Wheel D 69cm[1]

Gear Ratio Gearing cms
1 0.28 181.44
2 0.32 205.50
3 0.36 234.11
4 0.41 265.98
5 0.46 301.74
6 0.53 343.36
7 0.60 390.19
8 0.68 443.51
9 0.77 503.34
10 0.88 572.92
11 1.00 650.31
12 1.14 738.10
13 1.29 840.20
14 1.47 954.00

Bike used for a bit of cinder tracking and the odd hill. Normal riding
uses mostly gear 7/8. Hills require 1-3. I rarely use more than 11,
*never* the top gear.

I'm going to change that 48 for a 42, anyone any comments or think this
is a widely high gearing I have?


If your figures are correct, your gearing currently has a low gear close to
the highest gear of a standard racing road bike setup, and a high gear
more than three times as high as the highest gear on a standard road
racing setup. However, Sheldon Brown says you're wrong:
http://www.sheldonbrown.com/gears/internal.html

He says your top gear is currently 297cm (116 inches) and your bottom
currently 56.89cm (22.5 inches). These are still definitely in the racing
range; changing to a 42 tooth chainring would give you a range from 50cm
(19.6 inches) to 261.62 cm (103 inches) which is more similar to a normal
mountain bike range.

Ummm...I might have fscked it up, but the spreadsheet looks ok to me,
albeit in cms cos that's what I had on my tape measure

So it's (WD*PI)*(FS/RS)* Ratio

Where WD=Wheel Diameter, FS=Front Sprocket(Teeth), RS=Rear
Sprocket(Teeth) and Ratio is the multiplier for the given gear on the
Rohloff.

Given a 26.91" wheel gives 70" for the lowest gear, 152" for gear 7 and
372" for gear 14.

confused I've done something wrong haven't I?

Phil Cook wrote:
Simon Brooke wrote:


in message , Tosspot
') wrote:


Before I start, I realise this is very subjective, but here goes.

Surly Karate Monkey frame, with a Rohloff on 700c wheels (yeah, so shoot
me), gives a gearing of this;

Front 48T
Rear 16T
Wheel D 69cm[1]

Gear Ratio Gearing cms
1 0.28 181.44
2 0.32 205.50
3 0.36 234.11
4 0.41 265.98
5 0.46 301.74
6 0.53 343.36
7 0.60 390.19
8 0.68 443.51
9 0.77 503.34
10 0.88 572.92
11 1.00 650.31
12 1.14 738.10
13 1.29 840.20
14 1.47 954.00

Bike used for a bit of cinder tracking and the odd hill. Normal riding
uses mostly gear 7/8. Hills require 1-3. I rarely use more than 11,
*never* the top gear.

I'm going to change that 48 for a 42, anyone any comments or think this
is a widely high gearing I have?

If your figures are correct, your gearing currently has a low gear close to
the highest gear of a standard racing road bike setup, and a high gear
more than three times as high as the highest gear on a standard road
racing setup. However, Sheldon Brown says you're wrong:
http://www.sheldonbrown.com/gears/internal.html

He says your top gear is currently 297cm (116 inches) and your bottom
currently 56.89cm (22.5 inches). These are still definitely in the racing
range; changing to a 42 tooth chainring would give you a range from 50cm
(19.6 inches) to 261.62 cm (103 inches) which is more similar to a normal
mountain bike range.


It depends on how the gearing is expressed. Metric gear sizes are
usually metres development so straight conversion doesn't equate to
gear inches which is the equivalent diameter of wheel.

Putting 48 and 42 chainrings into Sheldon's calulator with atypical
700C wheel gives:

For 700 X 32 / 32-622 tire and 16 tooth sprocket
48 / 16 42 / 16
1.467 9.5 8.3
13.5 %
1.292 8.4 7.3
13.8 %
1.135 7.4 6.4
13.5 %
1 6.5 5.7
13.5 %
.881 5.7 5.0
13.8 %
.774 5.0 4.4
13.5 %
.682 4.4 3.9
13.7 %
.600 3.9 3.4
13.6 %
.528 3.4 3.0
13.8 %
.464 3.0 2.6
13.4 %
.409 2.7 2.3
13.6 %
.360 2.3 2.0
13.9 %
.316 2.0 1.8
13.3 %
.279 1.8 1.6
With Rohloff Speedhub 14-speed Hub

Or in gear inches

For 700 X 32 / 32-622 tire and 16 tooth sprocket
48 / 16 42 / 16
1.467 118.8 104.0
13.5 %
1.292 104.7 91.6
13.8 %
1.135 91.9 80.4
13.5 %
1 81.0 70.9
13.5 %
.881 71.4 62.4
13.8 %
.774 62.7 54.9
13.5 %
.682 55.2 48.3
13.7 %
.600 48.6 42.5
13.6 %
.528 42.8 37.4
13.8 %
.464 37.6 32.9
13.4 %
.409 33.1 29.0
13.6 %
.360 29.2 25.5
13.9 %
.316 25.6 22.4
13.3 %
.279 22.6 19.8
With Rohloff Speedhub 14-speed Hub

I would say that the 48 is a little overgeared. Dropping to a 42 is
the quivalent of dropping a gear step and looks eminently sensible to
me with a top gear equivalent to something between 52x13/14 which you
are only ever going to use when going downhill or with a srong wind
behind you. I can't imagine ever using the top gear provided by the 48
tooth ring.

phew That's what I thought, the whole shebang is over geared. I was
just looking for confirmation that 42 tooth was a ball park figure for
the front.

Thanks for the help.

"Tosspot" a écrit:

Surly Karate Monkey frame, with a Rohloff on 700c wheels (yeah,
so shoot me), gives a gearing of this;

Bike used for a bit of cinder tracking and the odd hill. Normal
riding uses mostly gear 7/8. Hills require 1-3. I rarely use more
than 11, *never* the top gear.

Whatever you end up doing, I'd pay particular attention to *not* spending
too much time in gear 7, or making the shift from 7 to 8 too often. 7th gear
is the least efficient, and the 7-8 shift is the least smooth.

James Thomson

Simon Brooke wrote:
Sheldon Brownsays you're wrong:
http://www.sheldonbrown.com/gears/internal.html

He says your top gear is currently 297cm (116 inches) and your bottom
currently 56.89cm (22.5 inches). These are still definitely in the racing
range;

Actually, a 22.5 inch low gear is WAY lower than you would ever find
on a racing bike.

Tosspot wrote:

Ummm...I might have fscked it up, but the spreadsheet looks ok to me,
albeit in cms cos that's what I had on my tape measure

So it's (WD*PI)*(FS/RS)* Ratio

Where WD=Wheel Diameter, FS=Front Sprocket(Teeth), RS=Rear
Sprocket(Teeth) and Ratio is the multiplier for the given gear on the
Rohloff.

Given a 26.91" wheel gives 70" for the lowest gear, 152" for gear 7 and
372" for gear 14.

confused Â*I've done something wrong haven't I?

Yep! It's π. π doesn't come into calculation of gear inches, because
that's a diameter based system.

You do multiply by π when calculating development in metres (nobody
uses centimetres for this.)

The quick and easy conversion is:

Gear inches X .08 = Metres Development.

However, you might do even better to use my new system: Gain Ratios

http://sheldonbrown.com/gain

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

in message , Tosspot
') wrote:

Simon Brooke wrote:
in message , Tosspot
') wrote:


Before I start, I realise this is very subjective, but here goes.

Surly Karate Monkey frame, with a Rohloff on 700c wheels (yeah, so shoot
me), gives a gearing of this;

Front 48T
Rear 16T
Wheel D 69cm[1]

Gear Ratio Gearing cms
1 0.28 181.44
2 0.32 205.50
3 0.36 234.11
4 0.41 265.98
5 0.46 301.74
6 0.53 343.36
7 0.60 390.19
8 0.68 443.51
9 0.77 503.34
10 0.88 572.92
11 1.00 650.31
12 1.14 738.10
13 1.29 840.20
14 1.47 954.00

Bike used for a bit of cinder tracking and the odd hill. Normal riding
uses mostly gear 7/8. Hills require 1-3. I rarely use more than 11,
*never* the top gear.

I'm going to change that 48 for a 42, anyone any comments or think this
is a widely high gearing I have?


If your figures are correct, your gearing currently has a low gear close
to the highest gear of a standard racing road bike setup, and a high
gear more than three times as high as the highest gear on a standard
road racing setup. However, Sheldon Brown says you're wrong:
http://www.sheldonbrown.com/gears/internal.html

He says your top gear is currently 297cm (116 inches) and your bottom
currently 56.89cm (22.5 inches). These are still definitely in the
racing range; changing to a 42 tooth chainring would give you a range
from 50cm (19.6 inches) to 261.62 cm (103 inches) which is more similar
to a normal mountain bike range.

Ummm...I might have fscked it up, but the spreadsheet looks ok to me,
albeit in cms cos that's what I had on my tape measure

So it's (WD*PI)*(FS/RS)* Ratio

Where WD=Wheel Diameter, FS=Front Sprocket(Teeth), RS=Rear
Sprocket(Teeth) and Ratio is the multiplier for the given gear on the
Rohloff.

Given a 26.91" wheel gives 70" for the lowest gear, 152" for gear 7 and
372" for gear 14.

confused I've done something wrong haven't I?

It's conventional in the UK just to use the diameter, not the
circumference, of the wheel to express the gear - dating back to the days
of the 'ordinary' bicycle. I have to confess 'metres development' was a
new one on me, so we've both learned something...

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

;; ... exposing the violence incoherent in the system...

Tosspot wrote:

Ummm...I might have fscked it up, but the spreadsheet looks ok to me,
albeit in cms cos that's what I had on my tape measure

So it's (WD*PI)*(FS/RS)* Ratio

Where WD=Wheel Diameter, FS=Front Sprocket(Teeth), RS=Rear
Sprocket(Teeth) and Ratio is the multiplier for the given gear on the
Rohloff.

Given a 26.91" wheel gives 70" for the lowest gear, 152" for gear 7 and
372" for gear 14.

confused I've done something wrong haven't I?


It's the inclusion of Pi, that is none-standard (fsvo standards). Gear
inches are usually expressed as relating to the _diameter_ of a
penny-farthing (ordinary) front wheel, not the distance around the
circumference.

So, drop the Pi, and order will be restored.

Other posters knew this, of course, but talking about 'three times the
gearing' made them feel clever.

All assistance short of actual help...