33 tooth chainring?

Ted said:

So does anybody known who makes a 33 tooth chainring for a Ultegra
crank?

TA make 74 mm PCD chainrings in most sizes from 24-36 T sizes, including 33.

--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
You can't have ham!

Ted said:

I'm having a Bike Friday built up. I'm going to be using a Ultegra
triple crank. The smallest chainring that I can use is 33 tooth. If I
try to use a smaller one it causes the chain to rub against the rear
brake.

So does anybody known who makes a 33 tooth chainring for a Ultegra
crank?

Yes, TA makes everything from 24 to 36 in the 74 BCD.

See: http://harriscyclery.com/74

Note, small wheel bikes such as Bike Fridays rarely need very small
chainrings, because the small wheels bias them toward low gearing.

See: http://harriscyclery.com/gears to calculate gear equivalencies
vis-a-vis bikes with full-sized wheels.

Sheldon "406" Brown
+----------------------------------------------------------+
| Injustice anywhere is a threat to justice everywhere. |
| -- Martin Luther King, Jr. |
+----------------------------------------------------------+
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 '406' Brown said:

Note, small wheel bikes such as Bike Fridays rarely need very small
chainrings, because the small wheels bias them toward low gearing.

(Shuffles nervously away, attempting to conceal Trice XXL with 24-34 bottom
gear)

--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
Apparently Guy has now got a Brompton. I'd never have guessed.

I opined:

Quoted message said:

Quoted message said:

Note, small wheel bikes such as Bike Fridays rarely need very small
chainrings, because the small wheels bias them toward low gearing.

Dave Larrington said:

(Shuffles nervously away, attempting to conceal Trice XXL with 24-34 bottom
gear)

I said _bikes_ not _trikes_. Trikes can use very, very low gears
because they can climb at very, very slow speeds without toppling over.

My Greensped GT3 goes down to a 1.4 Gain Ratio* (18.5", 1.5 meters) with
30/26 on 349 mm (16"😉 wheel.

The only times I've found need for such a low gear have been off-road,
and I had to switch to "3-wheel-drive" mode to get sufficient traction.

If I were carrying a touring load I could imagine using something lower
on pavement.

Sheldon "Limbo" Brown
*Gain ratio is a new system for measuring bicycle gearing.
It is explained in detail on my Web site at:
http://sheldonbrown.com/gain
+------------------------------------+
| I stood upon a high place, |
| And saw below, many devils |
| Running, leaping |
| And carousing in sin. |
| One looked up, grinning, |
| And said "Comrade, Brother!" |
| --Stephen Crane |
+------------------------------------+
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

quote='Sheldon Brown'Ted said:

I'm having a Bike Friday built up. I'm going to be using a Ultegra
triple crank. The smallest chainring that I can use is 33 tooth. If I
try to use a smaller one it causes the chain to rub against the rear
brake.

So does anybody known who makes a 33 tooth chainring for a Ultegra
crank?

Yes, TA makes everything from 24 to 36 in the 74 BCD.

See: http://harriscyclery.com/74

Note, small wheel bikes such as Bike Fridays rarely need very small
chainrings, because the small wheels bias them toward low gearing.

See: http://harriscyclery.com/gears to calculate gear equivalencies
vis-a-vis bikes with full-sized wheels.

Sheldon "406" Brown
+----------------------------------------------------------+
| Injustice anywhere is a threat to justice everywhere. |
| -- Martin Luther King, Jr. |
+----------------------------------------------------------+
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[/QUOTE]

Anyone make a 33T/110 bcd ring? I have a 66T.

I've a project I'm looking to use a small ring on a 305 shod folder-left tandem crank timing chain paired to a front tandem left crank ring mounted on a swb boom using double the teeth on the forward ring of the lower left crank. High gear ratios for the recumbent (front tandem) cranks, low climbing ratios for the upright cranks (rear tandem). Similar to the Reynolds Redundant, but as a folder and with differing upright and recumbent ratios.

Sheldon Brown said:

I opined:

Quoted message said:

Quoted message said:

Note, small wheel bikes such as Bike Fridays rarely need very small
chainrings, because the small wheels bias them toward low gearing.

Dave Larrington said:

(Shuffles nervously away, attempting to conceal Trice XXL with 24-34
bottom gear)

I said _bikes_ not _trikes_. Trikes can use very, very low gears
because they can climb at very, very slow speeds without toppling
over.

My Greensped GT3 goes down to a 1.4 Gain Ratio* (18.5", 1.5 meters)
with 30/26 on 349 mm (16"😉 wheel.

The only times I've found need for such a low gear have been off-road,
and I had to switch to "3-wheel-drive" mode to get sufficient
traction.

If I were carrying a touring load I could imagine using something
lower on pavement.

I used it up Bushcombe Lane on the Cotswold Corker audax ride. Max.
gradient here is 25% and there were plenty of people toppling into the
hedgerows with looks of envy on their faces...

I suspect that if I had a dual-406 recumbent two-wheeler, though, I'd have a
similar bottom gear.

--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
und keine Eie.

meb queried:

Quoted message said:

Anyone make a 33T/110 bcd ring? I have a 66T.

Yep, we've got 'em.

See: http://harriscyclery.com/110

(In general, you can find chainrings by sticking the BCD after our
domain URL.)

Sheldon "Acronyms" Brown
Newtonville, Massachusetts
+--------------------------------------------------------------+
| If you don't like yourself, you _can't_ like other people |
| --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

Sheldon Brown said:

My Greensped GT3 goes down to a 1.4 Gain Ratio* (18.5", 1.5 meters) with
30/26 on 349 mm (16"😉 wheel.

The only times I've found need for such a low gear have been off-road,
and I had to switch to "3-wheel-drive" mode to get sufficient traction.

If I were carrying a touring load I could imagine using something lower
on pavement.

I currently have a 20 inner chainring and 32 big cog on my two wheeled
700C bike. 35mm tires. Low gear of roughly 17 gear inches. No
problems staying upright. Used to have a 34 rear cog but the new
frames rear derailleur hanger would not allow the derailleur to clear
the 34 cog so I had to go back to the 32 cog. 20x34 was a 16 gear inch
low.

Dave Larrington said:

I used it up Bushcombe Lane on the Cotswold Corker audax ride. Max.
gradient here is 25% and there were plenty of people toppling into the
hedgerows with looks of envy on their faces...

I suspect that if I had a dual-406 recumbent two-wheeler, though, I'd have a
similar bottom gear.

Legs-

Next time you come to the U.S., let's make a side trip to L.A. and see
how well we do on Fargo Street's 33% grade:
http://www.pbase.com/coaster/fargo_street_2005

Looks like fun, eh?

At least if you topple sideways, you'll end up on someone's lawn,
instead of a hedgerow.

Jeff

Quoted message said:

I currently have a 20 inner chainring and 32 big cog on my two wheeled
700C bike. 35mm tires. Low gear of roughly 17 gear inches. No
problems staying upright. Used to have a 34 rear cog but the new
frames rear derailleur hanger would not allow the derailleur to clear
the 34 cog so I had to go back to the 32 cog. 20x34 was a 16 gear
inch low.

My #1 recumbent bike has 24/34 with a 559, which is about 17", while my
mountain bike will have 22/34 once I amass sufficient tuits to fir the new
oily bits currently lurking in the kitchen. These are, natch, entirely
superfluous to 99.999% of the terrain that either encounters these days.

--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
Never play leapfrog with a unicorn.

JeffWills said:

Next time you come to the U.S., let's make a side trip to L.A. and see
how well we do on Fargo Street's 33% grade:

We have a few of them over here. Wrynose and Hard Knott passes & Rosedale
Chimney to name but three.

Quoted message said:

Looks like fun, eh?

FSVO "fun" only, I suspect. Probably not even that much fun coming down...

--
Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
May you have an accident shaped like an umbrella.

Thanks everyone for the info on where to get a 33 tooth chainring. Its
a good thing Harris Cyclery had them as I searched the Internet and
couldn't find anybody else who had them.

So where did anybody get the idea you'd topple over if you went very
slow up hills. I am a slow climber and on some steep hills I will only
be going 2 to 3 mph and not falling over!

Ted

On 3 Jun 2005 09:56:31 -0700, "Ted" <[email hidden]>

Quoted message said:

Thanks everyone for the info on where to get a 33 tooth chainring. Its
a good thing Harris Cyclery had them as I searched the Internet and
couldn't find anybody else who had them.

So where did anybody get the idea you'd topple over if you went very
slow up hills. I am a slow climber and on some steep hills I will only
be going 2 to 3 mph and not falling over!

Ted

Dear Ted,

Well . . . if you're happy with your gearing, then the rest
of us should be happy, too.

I haven't followed the details of the thread, but if you're
riding a 700c tire with a 2124 mm circumference, using a
33-tooth front sprocket and a 34-tooth rear gear, then . . .

speed rpm
2.0 mph 26.0
2.5 mph 32.5
3.0 mph 39.0
3.5 mph 45.5
4.0 mph 52.0
4.5 mph 58.6
5.0 mph 65.0
5.5 mph 71.6
6.0 mph 78.1

At 2 to 3 mph, you'd be varying from 26 to 39 rpm, a cadence
rather lower than most people handle well under the strain
of climbing. At such low speeds, a drop of 1 mph for a minor
bump is about like hitting a wall--it's only a 1 mph drop
from 3 mph to 2 mph, but your cadence drops 33% in an
instant. It's not as if you have much momentum.

One possibility is that a closer look might show 3-4 or 4-5
mph as more typical. (A brisk walk is around 4 mph.) It
doesn't sound like much, but at those speeds, a drop of 1
mph is only a 25% or 20% drop in cadence--still bad, but not
as bad as 33%.

Another possibility is that you're just climbing a hill at a
cadence that suits you, but aren't as close to the maximum
as the kind of riders who worry about such things--if the
hill isn't as steep, you're still entitled to toil up it at
whatever pace works for you.

Cheers,

Carl Fogel