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Sweet spot problems

Old 09-29-18, 08:53 PM
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SlinkyWizard
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Sweet spot problems

So I have Giant Fastorad Comax 1, a flat bar road bike, the cassette is an 11x32 , and the crankset is 34/50

When I'm riding on flat, which is 95% of the time, I'm nearly always on the small chain ring, but my sweet spot is one gear higher than the one I'm in, problem is that one gear higher, I start to hear the cross chain sound.

So I go on the larger chain ring, but my sweet spot is where the cross chain sound starts, I go to a higher gear, but it slightly out of my reach, doable, but not ideal, . I like to ride between 25 -30 kph I am exerting some energy, but it is enjoyable.

It is not my goal to become faster, but to maintain a steady, comfortable speed over some distance, travelling to work and back, and for recreation.

Can the derailleurs be adjusted so when I'm in my sweet spot, both in large or small chain ring, there is not cross chain sound?
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Old 09-29-18, 08:58 PM
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Change the cassette or crank gearing is what I'd do. Fairly easy to do.
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Old 09-29-18, 09:04 PM
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If the cross chain sound is coming from your front derailleur can you give it another click without changing the gear.?? I can do it with my Schwinn. When I get that noise I look down at the front derailluer and I can see the chain isn't centered in it. I give a click left or right and the noise goes away.

I'm thinking this isn't happening in your case though. But have you looked down to see it.??
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Old 09-29-18, 09:10 PM
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You can adjust the front derailleur, to change that. But it shouldn't be a problem except on the one or two extreme gears on the rear; given what you say, I infer (perhaps not correctly) that you are hitting on a lot more gears, or that it isn't centered.

Try adjusting the front derailleur so that it only hits when crossed to the one or two most extreme gears; that should help. Otherwise you might have to change your gearing (which is not hard).

Last edited by 124Spider; 09-29-18 at 09:27 PM.
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Old 09-29-18, 09:19 PM
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If you're on the flat 95% of the time,

not much point in an 11/32 cassette.

11/25 might get you what you want.
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Old 09-30-18, 05:24 AM
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what are the ratios you are working with regarding the 11/32?

if you rarely use the next cog above the "cross chaining noise cog" , you might swap that one cog out to have two of the same favored cogs on that cassette... ?
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Old 09-30-18, 06:04 AM
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Your wide range 11-32 cassette shouldn't be cross chained all the way at those speeds with both chainrings. I'm guessing your front derailleur isn't adjusted correctly.
You should be able to use 10 of the 11 cogs in the big ring, and 9 of the 11 in the small ring. (sometimes the chain makes a ticking sound against the pickup rivets on the side of the big ring when the small is cross chained.)

Counting from big to small, which cog are you on when it's making noise? Get the cog number for the big ring and for the small ring.

(For metric challenged USA viewers, your usual 25-30 kph is about 16-18 mph.)

~~~
Even at low cadences, you shouldn't hear a cross chaining sound in both chainrings at the same speed.

Your 11-32 cassette at lower cadences. The 50 chainring is in black, the 34 in red:

If you were cross chaining in the 34-13 (which shouldn't make a noise) or the 34-12, then the 50 ring would use the 18 or 20 cog, right in the middle of the cassette.


Here's the chart at faster flat road cadences, near 90 rpm, typical for many riders.
The 25-30 kph range is near the middle of the cassette in either chainring.


The same in mph:

Last edited by rm -rf; 09-30-18 at 06:14 AM.
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Old 09-30-18, 06:09 AM
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Originally Posted by woodcraft View Post
If you're on the flat 95% of the time,

not much point in an 11/32 cassette.

11/25 might get you what you want.
12-25
I agree, it's easier to get the exact cadence with closer gearing.
The 11-speed 12-25 has very close shifts, but it's not good on steeper hills, of course. It's perhaps too close together, it often takes 4 rear shifts to reach the same cadence after shifting the front.




Originally Posted by Troul View Post
what are the ratios you are working with regarding the 11/32?

if you rarely use the next cog above the "cross chaining noise cog" , you might swap that one cog out to have two of the same favored cogs on that cassette... ?
It's complicated or impossible to change one cog on 11-speed cassettes.

Last edited by rm -rf; 09-30-18 at 06:13 AM.
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Old 09-30-18, 01:33 PM
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That's the beauty of the 34/50 chainset. Most used gears in the 34 are crossed.... most used gears in the 50 are crossed.........
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Old 09-30-18, 04:03 PM
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^^ +1
You need a 36T or 38T chainring. Love my triple crank.
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Old 10-01-18, 05:36 AM
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Thanks for the graph,

when in the small chain ring, my sweet spot is on the 13T , but I noticed the chain is rubbing on the front derailleur, thus making a sound, so I go to the easier 14T , and no sound,

when in the big chain ring, my sweet spot is on the 20T, but there is sound, so I go to the harder 18T, and the sound stops.

Will adjusting the front derailleur let me get into my sweet spot with no noise?

Shimano 105 11 speed drive train, Front derailleur is Shimano FD 5801
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Old 10-01-18, 05:47 AM
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Originally Posted by Troul View Post
Change the cassette or crank gearing is what I'd do. Fairly easy to do.
^This. Narrow the range between your front chainrings. You got great input above, where BF members did your homework for you. Use a gearing calculator to pictorially represent the gear ranges that you currently have and then ones that give you smaller increments around your "sweet spot". I agree that 32T is too much on the rear, and that the compact 50-34T is too large a jump on the front. Easiest thing is to change the outer front chain ring to something that is a better fit with your sweet spot preferred gear. Maybe down to a 44T or 46T or so. You'll need to use the calculator to see the changes. PG

Last edited by Phil_gretz; 10-01-18 at 05:48 AM. Reason: Recognizing the homework done by others.
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Old 10-01-18, 06:12 AM
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^This. Narrow the range between your front chainrings. You got great input above, where BF members did your homework for you. Use a gearing calculator to pictorially represent the gear ranges that you currently have and then ones that give you smaller increments around your "sweet spot". I agree that 32T is too much on the rear, and that the compact 50-34T is too large a jump on the front. Easiest thing is to change the outer front chain ring to something that is a better fit with your sweet spot preferred gear. Maybe down to a 44T or 46T or so. You'll need to use the calculator to see the changes. PG
Oh god, as much as I want to get into my sweet spot, at the moment, I don't want to spend extra money to get there, I didn't realize it was so scientific, at least from my perspective,

maybe I got to try a little harder to adjust my sweet spot to the big chain ring, 18T
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Old 10-01-18, 06:38 AM
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Originally Posted by SlinkyWizard View Post
Thanks for the graph,

when in the small chain ring, my sweet spot is on the 13T , but I noticed the chain is rubbing on the front derailleur, thus making a sound, so I go to the easier 14T , and no sound,

when in the big chain ring, my sweet spot is on the 20T, but there is sound, so I go to the harder 18T, and the sound stops.

Will adjusting the front derailleur let me get into my sweet spot with no noise?

Shimano 105 11 speed drive train, Front derailleur is Shimano FD 5801
Trim
The front shifter has a "trim" position, to move the derailleur cage slightly without shifting. It's for stopping the derailleur cage from a slight rubbing in some gear combinations. Do you use this?

Derailleur adjustments / tuning
The front derailleur needs to be adjusted correctly for smooth shifting and to keep from dropping the chain during a shift. The cage height above the big chainring, the angle of the cage edge along the chainring, and the cable tension are all critical.

Shimano has "dealer manuals" online. These are good if you want to do your own maintenance. They are detailed, step-by-step installation and adjustment procedures.

Here's the 105 front derailleur (also applies to other Shimano 11-speed models)
http://si.shimano.com/pdfs/dm/DM-RAFD001-02-ENG.pdf

Here's a video that may help:
Art's Cyclery Blog Ask a Mechanic: Shimano Front Derailleur Trim Set-Up and Adjustment

~~~~~~~~~~~~~~~

The manual has a confusing page about cross chaining in the small chainring:


indicating that the smallest 3 cogs might have noise. I thought it was usually just the two smallest cogs, not the third.
But they say "shift the chain to the second largest" ?? That makes no sense.
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Old 10-01-18, 06:58 AM
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Originally Posted by SlinkyWizard View Post
Oh god, as much as I want to get into my sweet spot, at the moment, I don't want to spend extra money to get there, I didn't realize it was so scientific, at least from my perspective,

maybe I got to try a little harder to adjust my sweet spot to the big chain ring, 18T
Yeah, don't spend any money on new gearing now.

Your 50 front - 20 rear gear combination should not be making noise. It's out of adjustment. Does the 50-22 make noise too?

~~~~
It's not a good idea to switch just one chainring to a different size. They are a matched set, with the pickup pins on the side of the big ring, and the machined edges of the big ring teeth designed to work with that small ring. (It's workable, I suppose, but not optimal.)

Chainring changes are proportional. Changing 34 to 36 is 36/34 = 1.06, or 6%. So the same cadence would increase speeds by 6%, with a 6% harder effort, of course. It basically shifts the blue charts I posted to the right by about 1.5 kph at flat road speeds: 25 kph goes to 26.5, for example. That's some help for staying in the small ring at a bit higher speed, but it's a fairly minor change.

Last edited by rm -rf; 10-01-18 at 07:03 AM.
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Old 10-01-18, 07:04 AM
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Properly adjusted, you should be able to use all but the two largest cogs when in the big ring (11-25) and all but the two smallest cogs when in the small ring (13-32.) Mechanically, you should be able to use every one of them, just with a bit of clatter at the big-big and small-small. If not, The derailleurs need to be adjusted.
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Old 10-01-18, 07:40 AM
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Originally Posted by SlinkyWizard View Post
Thanks for the graph,

when in the small chain ring, my sweet spot is on the 13T , but I noticed the chain is rubbing on the front derailleur, thus making a sound, so I go to the easier 14T , and no sound,

when in the big chain ring, my sweet spot is on the 20T, but there is sound, so I go to the harder 18T, and the sound stops.

Will adjusting the front derailleur let me get into my sweet spot with no noise?

Shimano 105 11 speed drive train, Front derailleur is Shimano FD 5801
If the noise is caused by the chain rubbing on the FD cage, like you say, then adjusting the derailleur will make the sound go away.
Does your bike have in-line adjusters on the shift cables? Some do, some don't. If yours doesn't; get some. They're pretty inexpensive, and will let you make these adjustments in a couple of seconds.

Tune the bike so it works best where you use it most. If you're rarely in the 52-11, then i wouldn't spend my time getting that one perfect at the expense of the -18 and -20 that you use 'all the time'
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Old 10-01-18, 12:18 PM
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A Shimano 105 11-speed should (i) have a micro-adjust ability, with which (ii) you can make it so that crossing rubs only on the most extreme cross. My 11-speed Shimano only rubs when I am on the large front ring and largest rear gear, or small front ring and smallest rear gear. You may have to adjust the front derailleur to achieve that.

If you don't know how to do that, and/or are unwilling to learn how to do that (perfectly understandable, though not hard to learn), bring your bike into a good bike shop, where then can make the adjustments, and show you how to trim, for very little money.
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Old 10-01-18, 03:57 PM
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I thought this thread was about Schwinn Homegrown Sweet Spots, and I got excited.
whistles on my way out....
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Old 10-01-18, 08:03 PM
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Originally Posted by SlinkyWizard View Post
So I have Giant Fastorad Comax 1, a flat bar road bike, the cassette is an 11x32 , and the crankset is 34/50

When I'm riding on flat, which is 95% of the time, I'm nearly always on the small chain ring, but my sweet spot is one gear higher than the one I'm in, problem is that one gear higher, I start to hear the cross chain sound.

So I go on the larger chain ring, but my sweet spot is where the cross chain sound starts, I go to a higher gear, but it slightly out of my reach, doable, but not ideal, . I like to ride between 25 -30 kph I am exerting some energy, but it is enjoyable.

It is not my goal to become faster, but to maintain a steady, comfortable speed over some distance, travelling to work and back, and for recreation.

Can the derailleurs be adjusted so when I'm in my sweet spot, both in large or small chain ring, there is not cross chain sound?
All good advice on adjusting FD, but your real problem is your gearing is too high for your riding. Get smaller chainrings and you will have less cross-chaining. I don't mind crossing, but not on a constant basis.

check your BCD on what options you have with your crank.
I have a 2x10 on my toughroad and it has a 42/28 crank and I never use my 42:11 because I'm too weak. (that would be 45 km/h). I probably could get by with a 38T. YMMV. i ride 99% of the time in the large chainring and can cross without problems. the small chainring is just a bailout after along day on a steep hill.

do you ever need lower gearing?
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Old 10-01-18, 08:31 PM
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this is why I got a 46 tooth big chain ring. For most recreational riding, 50/11 is a really big gear. For that matter 46/11 is a pretty big gear. Now I ride most of the time in the big chain ring. I actually wanted to go to a 44, but a crank I wanted with a 46 was available at my LBS, so that's what I got.
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Old 10-02-18, 05:23 AM
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Originally Posted by HerrKaLeun View Post
All good advice on adjusting FD, but your real problem is your gearing is too high for your riding. Get smaller chainrings and you will have less cross-chaining. I don't mind crossing, but not on a constant basis.

check your BCD on what options you have with your crank.
I have a 2x10 on my toughroad and it has a 42/28 crank and I never use my 42:11 because I'm too weak. (that would be 45 km/h). I probably could get by with a 38T. YMMV. i ride 99% of the time in the large chainring and can cross without problems. the small chainring is just a bailout after along day on a steep hill.

do you ever need lower gearing?
He said he l likes 50/20 for cruising. The 20 is in the 4th position of 11 cogs on his cassette. If that combination is making noise, something is wrong with the fd or the chainline. I'd say that's a bigger problem than fine tuning his gearing and it should be free to fix.
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Old 10-02-18, 07:06 AM
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I have the same bike. You shouldn't have any cross chain sounds. Mine is as quiet as can be. Sounds like you need some derailleur adjustment done. Don't forget your front derailluer has the trim option to eliminate the chain from rubbing on the front derailleur.
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Old 10-03-18, 01:42 AM
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Thank you everyone for your input, and help , great advice, things I never knew, a lot to digest for me,

I ended up taking the bike to the LBS where I got it from, the mechanic I think basically moved everything over 1 spot, so now my sweet spot on the small ring / 13 T doesn't make a sound,

but now the small chain ring / 32T makes a sound, but I barely use that gear, so I should be ok,

Also on the big chain ring / 20T there is a slight sound, BUT UNTIL YESTERDAY , I HAD NO IDEA ABOUT TRIM, so a little click, and the noise stopped

Unfortunately, the language barrier here is a bit of a problem , + bike culture, or cycling is relatively new in Korea compared to other countries I think, and as a result, the mechanics are not quite up to par.

Overall, the problem has been solved, I can get into my sweet spot without any sound,

I have the same bike. You shouldn't have any cross chain sounds. Mine is as quiet as can be. Sounds like you need some derailleur adjustment done
Ideally, if your bike makes no cross chain sound, then mine shouldn't either, I'm just not sure the guy can set it up so. I can always take the bike to another LBS, but for now, I'm happy.
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