box opener

feels that both shimano and other brands rear derailleur works less smoothly up hill, I was told that this is due to increased tension on the cable and derailleur, because the derailleur shifts via tension on cable, and the tension can be dramaticlly changed in various situations. So I am assuming that friction shifter only pulls cable at 1:1 ratio, which makes it less sensitive to cable tension variation, is this the case please?

Thanks for all of your opinions in advance!

HillRider

Derailleurs work less smoothly up hill because the chain is under more tension from your pedaling effort and the derailleur has to work harder to move it from one cog (or chainring) to another. It has nothing to do with cable tension except you need more of it to move the derailleur.

trailangel

""I was told that this is due to increased tension on the cable and derailleur, because the derailleur shifts via tension on cable, and the tension can be dramaticlly changed in various situations""
I always hear....'I was told' but nobody ever comes clean and says who told them the bad info.
Now I am asking......Who Told You?

box opener

The derailleur has to work harder, which means it need to be pulled harder by the cable and thus it has to do with the cable tension, am I getting it wrong please?

cyccommute 

The derailer (proper spelling) works by "derailing" the chain during shifts. When you are climbing a hill, you have more tension on the chain which means that it takes more force to "derail" the chain to the next cog. With a traditional freewheel and "regular" teeth, the derailer may not be able to push the chain off the cog to the next one, especially if you are trying to downshift, i.e. pull the chain onto a larger cog. The derailer works a bit harder but it's the chain that is really doing the work.

Modern index systems use ramps on the cogs to assist in shifting so that the whole process is smoother and less difficult. When you "click" the shifter, the derailer will start to move and as soon as the chain catches one of the ramps, it moves. A momentary relaxing of pressure on the chain helps. Old unramped cogs will clatter more and you have to put a bit more pressure on the shifter to make it move, which usually results in an overshift.

Generally, modern cogsets have negated the issues of downshifts for bikes. If you click, it will shift.

box opener

There is no problem on chain downshifting for the rear derailer, it works fine ever since, which means shifting towards the smaller cog for my bike, and which means the tension on the chain is further relieved, the problem is that when I am going up hill, I hope the rear derailer can shift the chain to larger cog that could make pedaling easier for me, and this is where the failure of derailer most take place. Do you have any idea on improving that, how do you think of replacing the indexed rear derailer to friction derailer? does that help evidently?

Bill Kapaun

Have you had a problem with this?
Yes or no?

John Lesar

A friction shifter is simply a lever to pull or release the cable. It doesnt really care what kind of derailler you have.
Its job is to maintain the position of the derailler on the cog you have selected.

trailangel

Downshifting is shifting to a larger cog on the rear derailleur, not to a smaller cog.

box opener

when the chain is under increased tension will friction shifter make better shifting？

trailangel

No

fietsbob

friction shifter just pulls the cable , which in turn pulls the rear derailleur across the gear cluster, inward. **

the friction holds it against the return spring tending to pull it in the opposite direction.

** front return spring pulls to low, rear, return spring pulls to high.


the tension on the chain makes changing gears while going up hill, quite difficult.
but once the tension is reduced, by heading down hill, the derailing from one cog to the other, is easier.

this also applies to any derailleur , friction or indexed..
you need to take the tension off the chain, to have it derail off one cog and onto another..

Technique over buying fancier hardware..



....

cyccommute 

Downshifting on a bike is going to the larger cog on the back as trailangel pointed out. This is harder for the chain to do because the chain is under more torque from the force you are putting on the pedals as you ride uphill. That's why most derailers...at least the ones that work well...use the cable to pull the chain up onto the larger diameter (but lower gear) cog. On an upshift (going to a higher gear) there's not as much torque and the return spring can handle the job.

Front derailers often have a hard time downshifting (going to the smaller chainwheels in the front) because the return spring isn't strong enough to move the chain over. Shimano should have made their Rapidrise for the front so that the derailer drags the chain onto the smaller gear. The shifts are easier and more reliable.

Indexing should work better than friction because you basically click and the bike shifts. Loose cables or using the wrong cable housing...for example, using wound cable housing instead of compressionless housing...will make index suffer but going to friction won't make it "better".

Bill Kapaun

It can, since you can easily push the lever a "little more", and force a shift if needed.
The whole idea is that you push (or pull) the lever UNTIL it shifts, so it's just a matter of YOUR skill and you/shifter ergonomics.
Ergonomics can have a major impact on shift quality.
When I had friction on my Rockhopper, my shifting got better as I went from 7 to 8 to 9 speed. The amount of "push" needed better matched MY shifter ergonomics with MY hand.

coupster

If you're having troubling shifting to an easier gear while slogging uphill, you need to improve your technique - not your mechanicals. As everybody has said the problem is based on the tension on the chain. The more force on the pedals, the more tension on the chain, the tighter the chain will hug the cogs of the gear, the harder the derailleur will have to work to move the chain. If everything is maxed out the derailleur may not even be able to move the chain.

You need to plan your uphill shifts. As soon as you think "I gotta shift" and you reach for the shifter, ease up on the pressure on the pedals. As you ease up, shift. And start pedaling again. That almost instantaneous pause in pedal pressure will release enough tension on the chain allowing the rear derailleur to derail the chain onto the next gear. As you get better you'll do it all unconsciously and lose no forward momentum. Before that time you'll wobble a bit and think this is stupid I need to keep pedalling. But this technique will actually make climbing hills easier and relieve an enormous amount of unnecessary stress on the entire drive train.

SkyDog75

When applying force to the pedals, the crankset is pulling the chain, meaning the top run of the chain is under tension. The bottom run of the chain is not under tension, except tension from the rear derailleur spring. The rear derailleur works on the bottom run of chain, so it's not nearly as affected by pedaling force as the front derailleur, which works on the top run of the chain. You definitely need to lay off pedal pressure when shifting the front, otherwise your derailleur will be fighting to derail a tightly-engaged chain.

HillRider

Yes, front shifting is definitely more effected by chain tension and, given enough tension it it may be nearly impossible to shift between chainrings.

However, rear shifting is also negatively impacted by high chain tension, just not to the same extent. The high tension at the top of the engaged cog does resist the chain being moved off of it.

cny-bikeman

If you want to make shifting to a lower gear (larger rear cog) easier there are two ways:
1. Shift earlier.
2. Let up slightly on pedal pressure as you shift, which will allow the chain to be more easily pushed to the larger cog. Note that if you wait too long it will be difficult to do this method as well.

Cable tension has nothing to do causing shifting difficulty. That you have to pull harder on the cable is a reaction to a harder shift due to chain tension, not the cause of it.

cyccommute 

That's only because the front derailer is designed wrong. It relies on the spring to knock the chain off during high torque situations while using the cable to drag the chain off the chainwheels during low torque situations. The rear, on the other hand, works in the opposite, and proper, way.

Shimano's RapidRise is (mostly) a failure because they concentrated on the wrong derailer in an effort to have the shifters work the same way. Long ago Suntour made a front derailer that use the cable to drag the chain off on to low gears in high torque situations and it worked wonderfully. None of that "CLATTER! CLATTER! CLATTER!, drop the chain" foolishness especially in off-road riding. Shimano would have had a real winner if they had done RapidRise on the front derailer.