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What is the difference between SIS shifting and friction shifting?

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What is the difference between SIS shifting and friction shifting?

Old 10-06-14, 08:57 AM
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09box
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What is the difference between SIS shifting and friction shifting?

Is there anyway to explain it in layman's terms? I noticed where you can pick between the two on one of my bar end shifters.
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Old 10-06-14, 09:10 AM
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SIS is the name given to the first generation of successful 1980's Shimano indexed shifting that developed into what is now being sold by them. The index setting allows you to work with direct friction without indexing. At the time, Shimano understood that their previous attempts (low-end market "Positron") at indexing were so disastrous that no serious bike rider would have tried the indexing without this lock-out feature.
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Old 10-06-14, 09:13 AM
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In layman's terms, that means that, when it's on the index setting (assuming you have everything adjusted right), there are a series of "clicks" in the lever (you can both hear and feel them), and it will shift one gear over every time that you push the lever to the next click. The friction setting lacks those "clicks", so you have to push the lever until you hear the gear change and then you stop pushing. With time and practice, you get a feel for how far to push without listening or pushing too far and the friction setting lets you shift even when your adjustments aren't perfectly spot on. Some people prefer one, others prefer the other.
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Old 10-06-14, 09:13 AM
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Originally Posted by 09box View Post
Is there anyway to explain it in layman's terms? .
It is like the difference between using white-out to correct typos on your Royal typewriter and auto-correct on your PowerBook.

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Old 10-06-14, 09:15 AM
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SIS stands for Shimano Index System (or something like that) but is used interchangeably with index shifting.

Indexing shifting is where you pull or push on the shifter until it 'clicks' and the rear derailleur moves or indexes the chain onto the selected cog.

Friction shifting is where you manually move and adjust the chain onto the selected cog and then trim the derailleur.

Accushift is Suntours name for it, as Mentioned Shimano coined SIS, and Campagnolos first attempt was called Syncro, but that sort of a hybrid system where is clicked but required a little over shift and sometimes some trimming.

Shimanos move to SIS, SLR (Shimano Leaner Respones) and STI (Shimano Total Integration aka brifters) was as much about forcing bike builders/sellers to use all or no shimano. derailleurs of course would only index with shimano shifters but they also tried to make the brakes feel spongey and weak if you didn't use shimano brake levers and calipers together. OOOPs sorry I'll stop shipmano bashing now.
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Old 10-06-14, 09:24 AM
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So, SIS=more precise and you hear clicking
Friction=less precise, little rougher, no clicks?
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Old 10-06-14, 09:24 AM
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The other key to successful index shifting is for the derailleur to move the chain the exact right amount per click, to get to the next cog, and for the cogs to be correctly spaced for each move. Suntour, Shimano and Campagnolo all had different spacing and shifter/derailleur pull ratios.
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Old 10-06-14, 09:31 AM
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Originally Posted by 09box View Post
So, SIS=more precise and you hear clicking
Friction=less precise, little rougher, no clicks?
Go ride w/ it "on" and then "off", more useful than typing.

Since "I noticed where you can pick between the two on one of my bar end shifters" you already have it set one way or 'tother.
Ride as is, set it to Way #2 ride and voila' you will have the actual experience .
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Last edited by Bandera; 10-06-14 at 10:27 AM.
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Old 10-06-14, 10:03 AM
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Originally Posted by 09box View Post
So, SIS=more precise and you hear clicking
Friction=less precise, little rougher, no clicks?
I don't know. I'd say Friction is more precise because you can put the chain exactly where you want it rather than only where those little clicks let you. On the other hand, SIS is easier for someone who is less experienced. You don't have to think about it; if the pedaling gets to be difficult, you just push the lever until the next click, and suddenly the pedaling is easier again. With experience, friction gets to be as easy and more functional, but it's one more thing to think about when starting out. I'd probably compare friction vs indexed to manual vs automatic transmissions in cars but less of a difference. Friction isn't as hard as a stick shift and indexed isn't as easy as an automatic, but it's kind of along those lines.
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Old 10-06-14, 10:13 AM
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Good explanations so far. I think of:

SIS/Index = car with automatic transmission.

Friction = car with manual transmission.

Not exactly, of course, but you can get the idea.
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Old 10-06-14, 11:06 AM
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I would say:

Brifters: Paddle shifters
Index DT: Manual
Friction: ????
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Old 10-06-14, 11:15 AM
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Originally Posted by Bandera View Post
Go ride w/ it "on" and then "off", more useful than typing.

Since "I noticed where you can pick between the two on one of my bar end shifters" you already have it set one way or 'tother.
Ride as is, set it to Way #2 ride and voila' you will have the actual experience .
-Bandera
Exactly.
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Old 10-06-14, 11:29 AM
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Digital or analog.
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Old 10-06-14, 12:04 PM
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FWIW, you're not going to find bar-ends with friction shifting/Index on most current production bikes other than touring rigs; the idea is that even if you take a hit to the derailler/etc you can still change over to friction mode and have a usable range of gears. Indexed shifting is far less tolerant of misadjustment or damage.
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Old 10-06-14, 03:16 PM
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Originally Posted by 09box View Post
Is there anyway to explain it in layman's terms? I noticed where you can pick between the two on one of my bar end shifters.
Being able to switch between index and friction was a very nice feature of the SIS downtube and bar-end shifters. This was super handy when you switched wheels for whatever reason and still wanted to be able to shift, because the index settings may not work well or at all on a different wheel. I'm a little surprised that nobody has solved this problem with brifters, though there have been a few attempts to make an easy adjust at the barrel stop.
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Old 04-23-19, 06:14 PM
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No idea about how Shimano SIS works

I am a bike moron. I just bought a bike today that says Shimano-equipped. It has a Shimano Tourney SIS ( Shimano TZ) and has a 7-Speed Index. Everytime I rest my feet from pedalling, the chain makes a noise and loosen up from the sprocket. I don't know what the heck is happening with the bike. Will somebody help me with my ignorance and tell me what to do to enjoy my daily afternoon bike exercise. Much appreciation for your help.
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Old 04-24-19, 07:16 AM
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Originally Posted by kyle70b View Post
I am a bike moron. I just bought a bike today that says Shimano-equipped. It has a Shimano Tourney SIS ( Shimano TZ) and has a 7-Speed Index. Everytime I rest my feet from pedalling, the chain makes a noise and loosen up from the sprocket. I don't know what the heck is happening with the bike. Will somebody help me with my ignorance and tell me what to do to enjoy my daily afternoon bike exercise. Much appreciation for your help.
It sounds like you have a freewheel problem, whereby the freewheel is trying to drive the chain when you coast. Freewheels are so inexpensive that it's not worth the effort for most novices to buy the tools to take them apart for repair.


However, before you buy a replacement freewheel, there is one simple repair that may fix the problem. Remove the wheel and lay it on it's side, freewheel facing up. Dribble some light oil around the outer edge of the freewheel cover plate, while spinning the cogs backwards. The oil should seep into the freewheel and may free up the movement. Alternately, some members first dribble solvent to free things up, then dribble oil, to lubricate the internals. If you have the tool to remove the freewheel first, it does make things easier and much neater, but it's not mandatory.
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Old 04-24-19, 07:42 AM
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It is extremely easy to learn the art of accurate non-indexed shifting. Unless you are racing in a peleton, indexing brings little added value.

For me, the big arguments in favor of friction shift or a linear-throw indexed shift with a friction option are: 1) near-universal compatibility among mix-and-match components; 2) ability to shift quickly and smoothly across any number of cogs; 3) ease and stability of adjustment. All of my road bikes have no-index shift -- either barcons or downtube levers -- and my mountain bike has 7-speed SunTour XC thumbies, which I have always kept in friction mode. Now that I run an 8-speed Shimano cassette on the mountain bike, friction mode has become mandatory.
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Old 04-24-19, 09:16 AM
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Originally Posted by kyle70b View Post
I am a bike moron. I just bought a bike today that says Shimano-equipped. It has a Shimano Tourney SIS ( Shimano TZ) and has a 7-Speed Index. Everytime I rest my feet from pedalling, the chain makes a noise and loosen up from the sprocket. I don't know what the heck is happening with the bike. Will somebody help me with my ignorance and tell me what to do to enjoy my daily afternoon bike exercise. Much appreciation for your help.
Hi Kyle-

Read what T-Mar wrote-

What should happen is when you stop pedaling- the internals of the freewheel should allow everything but the cogs to spin- but what is happening is something is gummed up inside so the internals can't spin- forcing the cogs to spin- making your chain bunch up.

Do what T-Mar suggested-

Try the light oil around the outside of that inner ring- and work it in there.




If you use WD40 or something- you have to use oil or another lubricant after. WD40 will dissolve any lubricant in there.

Good Luck!


If worst comes to worst- another freewheel is under like $20.
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Old 04-24-19, 09:51 AM
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Index= Trumpet. There are valves for the different notes.
Friction=Trombone. You move the slide 'til you get there.
Over time, friction shifting becomes like playing the trombone-you just know where it is. I've been riding friction for 50 years and see no reason for index, brifters, or GASP!-Di2. There's also a helluva lot less to go wrong with friction and a helluva lot cheaper to fix when it does.
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Old 04-24-19, 09:51 AM
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Sorry to confound things, but depending on the age of your bike, with 7 speeds in the rear, you may have a cassette and freehub rather than a freewheel. Same problem, but the solution would be different. Take another look back there, focusing on the outside end where smallest cog/sprocket is. Does it look like The Golden Boy's pic above, with a recess around the central opening? Or is it more flat:

like this? If it's the latter, you have a cassette, a set of sprockets that slides over the freehub. You'd have to remove the cassette (which requires a couple bike-specific tools) to reach the ratcheting mechanism of the freehub to lubricate it.

Do you have a bike co-op / "bike kitchen" where you live? If so, there's probably a day you could go in and use their tools, and sponge off their expertise, to determine what you have and how to lubricate it.
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Old 04-24-19, 12:00 PM
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tuning your radio by electronic preset (index)
tuning your radio by turning the knob (friction)
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Old 04-24-19, 07:08 PM
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Friction shifting allows the derailleur an infinite number of positions to be in. It is, at times, depending on your level of riding expertise, necessary to "trim" your shift a wee bit more or less to find the sweet spot. Indexed shifting requires that you pull the shift lever enough for it to click. If properly adjusted, that click will accurately position the drive chain on the correct cog (rear wheel) with no need to fuss around to get it perfect.

For my money, I definitely prefer indexed shifting. The new shifter design, called Brifters (Brake + RIFTERS = Brifters) are indexed shifting components and my absolute riding preference.
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Old 04-24-19, 10:24 PM
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Everyone needs to look at the dates of the posts. This thread ran its course in 2014 and was dormant until Kyle revived it with a sort-of-unrelated question.
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Old 04-25-19, 06:33 AM
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Originally Posted by ryansu View Post
tuning your vintage analog car radio by mechanical push-button preset (index) tuning your radio receiver by turning the mechanical tuning knob (friction)
fify
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