3x drivetrain L/R spacing question
04-12-24, 10:53 AM
#26
Senior Member
Thread Starter
Join Date: Oct 2023
Location: New Jersey
Posts: 576
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 366 Post(s)
Liked 276 Times
in
176 Posts
Have you actually calculated that angle?
A few years ago I did a rough estimate because of the ongoing cross chaining argument. It is easy math. The angle is quite small at the extremes. The result of changes in cassette is frightfully minute.
I can’t imagine increasing chainstay length while maintaining good design geometry would have any appreciable difference.
Wading around in tenths, more appropriately minutes, of a degree is pretty far into the weeds.
Johh
A few years ago I did a rough estimate because of the ongoing cross chaining argument. It is easy math. The angle is quite small at the extremes. The result of changes in cassette is frightfully minute.
I can’t imagine increasing chainstay length while maintaining good design geometry would have any appreciable difference.
Wading around in tenths, more appropriately minutes, of a degree is pretty far into the weeds.
Johh
04-12-24, 11:10 AM
#28
Senior Member
Join Date: Feb 2015
Location: Mission Viejo
Posts: 5,809
Bikes: 1986 Cannondale SR400 (Flat bar commuter), 1988 Cannondale Criterium XTR, 1992 Serotta T-Max, 1995 Trek 970
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 1944 Post(s)
Liked 2,170 Times
in
1,324 Posts
The only issue is if you don't anticipate and make the change soon enough. Then there is a good chance you get to stop and pick up the pieces of the RD as there is no way that return spring will get the chain into the large cog under load.
John
04-12-24, 11:47 AM
#29
Rider. Wanderer. Creator.
Join Date: May 2007
Location: New Jersey
Posts: 776
Bikes: Bike Friday Pocket Rocket, Cinelli Hobootleg, Zizzo Liberte
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 396 Post(s)
Liked 788 Times
in
378 Posts
Let's say that you are rolling down a small hill to the bottom and then climbing out the other side. And let's say that at the bottom you are in your highest gear, but climbing back up you will need your lowest gear.
Because it all happens so fast, you don't use every possible gear. You're going to do every click on the rear shifter and only make the two shifts on the front. The question is when to make them.
Here's the same idea with nomenclature:
My bike has:
11,12,13,14,15,16,17
21,22,23,24,25,26,27
31,32,33,34,35,36,37
Do I go through
37,36,35,25,24,23,13,12,11
or
37,36,26,25,24,23,22,12,11
or
37,27,26,25,24,23,22,21,11
or something else?
I'd like to have this particular highest to lowest shifting pattern pretty well practiced and memorized because it is a fundamental part of riding the bike that I don't want to think about too much in traffic.
Because it all happens so fast, you don't use every possible gear. You're going to do every click on the rear shifter and only make the two shifts on the front. The question is when to make them.
Here's the same idea with nomenclature:
My bike has:
11,12,13,14,15,16,17
21,22,23,24,25,26,27
31,32,33,34,35,36,37
Do I go through
37,36,35,25,24,23,13,12,11
or
37,36,26,25,24,23,22,12,11
or
37,27,26,25,24,23,22,21,11
or something else?
I'd like to have this particular highest to lowest shifting pattern pretty well practiced and memorized because it is a fundamental part of riding the bike that I don't want to think about too much in traffic.
- I usually do 2-3 shifts of the rear from the big chainring.
- Then I shift to the middle ring and adjust the rear if needed, usually just 1 shift back down (harder)
- Then I do 3-4 shifts of the rear from the middle chainring
- Then I shift to the granny ring and adjust the rear if needed, usually 2 shifts back down (harder)
- Then I do 3-4 shift of the rear from the granny ring
__________________
--------------------------------------
Rider. Wanderer. Creator.
JohnMFlores.com | YouTube: JohnMFlores
Insta: JohnMichaelFlores | TikTok: @johnnymotoflores
--------------------------------------
Rider. Wanderer. Creator.
JohnMFlores.com | YouTube: JohnMFlores
Insta: JohnMichaelFlores | TikTok: @johnnymotoflores
04-12-24, 11:49 AM
#30
Newbie
Join Date: Feb 2009
Posts: 74
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 33 Post(s)
Likes: 0
Liked 12 Times
in
9 Posts
Some examples:
11 means the easiest gear to pedal front and back (the lowest gear possible on the bike)
12 means the easiest gear in front, the second easiest in back
21 means the middle gear in front, the easiest in back
27 means the middle gear in front, the hardest in back
37 means the hardest gear to pedal in front and in back (top speed in this ratio)
The first digit (1, 2, or 3) corresponds to the small, middle or big gear on the front. The second digit (1-7) corresponds to the back gear (largest=1, smallest=7).
I like visualizing the gears this way. For example, I try to start from a stop in "22" and then shift up to "23", then "24". The two digits together make a number that roughly corresponds to how fast I will go in that gear. I think of the front gear in the "10s" place because it makes a bigger difference.
Also, I am a fan of the mountain bike style shift levers that I have. You can literally "feel" with the side of your knuckle what gear you are in without looking or moving your hands. No other style of shifter has this benefit.
11 means the easiest gear to pedal front and back (the lowest gear possible on the bike)
12 means the easiest gear in front, the second easiest in back
21 means the middle gear in front, the easiest in back
27 means the middle gear in front, the hardest in back
37 means the hardest gear to pedal in front and in back (top speed in this ratio)
The first digit (1, 2, or 3) corresponds to the small, middle or big gear on the front. The second digit (1-7) corresponds to the back gear (largest=1, smallest=7).
I like visualizing the gears this way. For example, I try to start from a stop in "22" and then shift up to "23", then "24". The two digits together make a number that roughly corresponds to how fast I will go in that gear. I think of the front gear in the "10s" place because it makes a bigger difference.
Also, I am a fan of the mountain bike style shift levers that I have. You can literally "feel" with the side of your knuckle what gear you are in without looking or moving your hands. No other style of shifter has this benefit.
I don't obsess about exactly where I change from big ring to middle ring to small ring, to be honest. Generally speaking I would rather make changes on the rear than the front. So I won't go up to the big ring, which is a bit of an effort, if I think I'm not going to be there for very long. I'll just stay in a small rear sprocket for a bit, if I can see I'll not need to be there for long.
Likes For stratman:
04-12-24, 02:11 PM
#31
Senior Member
Join Date: Feb 2017
Location: Northern Shenandoah Valley
Posts: 4,141
Bikes: More bikes than riders
Mentioned: 36 Post(s)
Tagged: 0 Thread(s)
Quoted: 1446 Post(s)
Liked 762 Times
in
570 Posts
I think it makes sense to think of your chain rings as "ranges" of gear ratios, using the left side shifter (controlling the front derailleur) to change between these different ranges. Think of them as low-speed, mid-speed, and high-speed. You use your left shifter to switch between these ranges and then you use your right side shifter (controlling the rear derailleur) to fine-tune your pedal cadence. If your speed changes pretty quickly (on either a sharp decline or a sharp incline), you'll be shifting pretty rapidly on the right shifter to keep up and you'll find that you quickly run out of range...it'll likely either get too hard to pedal or too fast to pedal pretty quickly. Rather than doing that, this is where you'd use your left shifter instead to either step up a range or step down a range. (Of course, if it's a REALLY dramatic change in speed, you may need to use both the left and right shifters to adjust accordingly.)
04-12-24, 02:15 PM
#32
Senior Member
Join Date: Feb 2017
Location: Northern Shenandoah Valley
Posts: 4,141
Bikes: More bikes than riders
Mentioned: 36 Post(s)
Tagged: 0 Thread(s)
Quoted: 1446 Post(s)
Liked 762 Times
in
570 Posts
Some examples:I like visualizing the gears this way. For example, I try to start from a stop in "22" and then shift up to "23", then "24". The two digits together make a number that roughly corresponds to how fast I will go in that gear. I think of the front gear in the "10s" place because it makes a bigger difference.
