Wingnuts77

Hi,

I have been refurbishing an old MTB and until the above issue it has been going well.

In brief, the issues were that the chain was slipping, which is why it hadn't been used for about a year.

I replaced the cassette with a brand new similar 8 speed one and also the chain with a new one for an 8 speed cassette. Since then I have also replaced the FD like for like and both shifters pretty much like for like, but the same configuration of 3 and 8. All cables too.

Everything was going well until I came to shifting the FD. I have followed pretty much every piece of advise I can find and just cannot get over the issue of not being able to maintain the front shifter on the largest chainring.

If I undo the gear cable from the cable clamp and just apply pressure by pulling the cable by hand from between the end of the outer cable and the guide under the bottom bracket I can manipulate the issue either way. If I apply what I consider to be normal pressure the shifter won't make the second shift into 3rd gear. However, if little or no pressure is applied the shifter makes the 3rd gear as expected. The shifter is a brand new Shimano ST-EF51, I know these are cheap and cheerful but they should still do the job.

Lastly, I have followed the guide on YouTube by Park Tools to the letter in relation to the FD, RD, replacing the cables and just about everything else. I have installed the FD from scratch, set it up with the L screw holding the cage in place aligned with the outer chainring. I have secured the cable while in this position as well as the conventional setup of securing the cable while the cage is in it's innermost position and everything else and as far as I can tell it all comes back to the shifter being unable to make the second and final latch to secure the dérailleur in position. The limit screws are not in play here as I have eliminated them by unscrewing them out of contention. Additionally, the new shifters don't seem to have any way of adjusting the lever stroke which I don't think applies to shifting gears in any case.

Isn't it the shifters sole purpose to actually create tension by shortening the working length of the cable and thereby actuating the dérailleur in the first place?

I have spent an embarrassing amount of time on this and just cannot understand what I need to do to make it work. Any help at all will be greatly appreciated.

Kind regards,

Wingnuts.

dsbrantjr

What kind of shifter are you using? Friction, trigger, twist, etc? A model number would be ideal.

Bill Kapaun

How do you apply "normal" pressure without applying "little" pressure first?

Wingnuts77

Shimano ST-EF51

Wingnuts77

You don't I guess.

I started by pulling the cable a little bit at a time while rotating the pedals and changing from the middle ring to the outer ring and back, until the tension in the cable became too great for the shifter to 'click' into place. Which in my non-professional minimal knowledge was not very much at all.

I did follow the instructions from another post here, albeit it was specific to a different set of components altogether, that suggested starting by setting the cable tension AFTER setting the H Limit while the cage was in the initial install/setup position. Which I thought might work as the cable tension was set with the shifter in 3rd gear and not under any duress whatsoever. However this proved fruitless too.

I'm really stumped by this as I cannot understand what exactly is changing within the shifter when it's under pressure, particulary as they're designed for the very purpose.

Would a few photos help at all?

Andrew R Stewart 

The classic start to set up cable tension is to have the lever in the default "normal" position, this is the small ring for most all current designs. So lever in the no cable pulled position and the chain and der in the smallest ring. Then snug up the cable tension while tightening it's anchor bolt. This is what I call the base line, where you start fine tuning from. I didn't think this is what you did from my reading of your last post. I do set the low limit screw as well as I can before to bring the ft cage as outward as it will likely be. Some systems like more cable tension form this base line. Some less. That's the fine tuning part. Generally the shift out to the large ring should also have the lever ratchet just clicking into place about the same time as the travel is limited by the high screw.

What's changing in the shifter? The shifter is just a pulley or spool that turns and the cable end is wound up along this pulley's outer surface. How big around and how much rotational movement controls how much cable is pulled (or released out). In practice these cable movement details are matched up with the cage shape, width, travel per MM of cable pull, ring spacing and such. Andy

tomtomtom123

It's difficult to understand your description. What I assume is that you can shift the front derailleur from 1st to 2nd chainring, but not from 2nd to 3rd chainring, when using the trigger shifter. However, if you pull the cable by hand, you are able to shift 2nd to 3rd chainring, if you pull the cable lightly.

I think you have to first work on adjusting the FD position, limit screws, and cable tension. Also check that the gap between the bottom of the outer plate of the FD cage is approximately 2mm above the teeth of the outer chainring.

One of the problems might be the cage rotation. Although the park tools video says to align the outer cage plate to be parallel with the chainrings, if the tail of your FD cage flares out very wide, then your inner cage plate might have quite a large angle away from the chainrings. This might make it difficult for the inner cage plate to press the chain against the outer chainring when you're trying to shift from the 2nd to 3rd chainring. You could experiment with rotating the tail of your FD, a little bit at a time, to make the inner cage plate more parallel to the chainrings. If you do so, you'll also have to readjust your L and H limit screw, and the cable tension with the barrel adjuster.

Also, another problem might be the lack of enough cable pull by the trigger shifter, if the trigger shifter is not designed for your FD. Or, if the entry angle of the cable into the FD, or the side that the cable is bolted onto to the FD is wrong, it could reduce the effective amount of FD movement for the same amount of cable pull. For example, if your FD is a standard bottom pull mechanics, the further the cable enters from the left, the less FD movement there is, while the further the cable enters from the right, the more FD movement there is for the same amount of cable pull. And usually, if the cable was passed through the top/left of the anchor bolt, it will produce less FD movement than if the cable passed through the bottom right of the anchor bolt. Some of the Shimano FDs have a reversible pin to change the pathway of the cable around the anchor bolt, in order to give you an option to reduce or increase the FD movement.

andrewclaus

The last paragraph in post 7 above is my guess. I see that a lot at the coop. Again, photos would help.

Wingnuts77

Hi Andrew,


I have installed the FD in every way you can think of.From the smallest chainring working my way up with the chain also in every position, to the outside edge of the FD aligned with the largest (3rd) chainring with the cable not attached until after this was complete, all to no avail.


I did think that working from the largest chainring first, albeit rather unorthodox might work as the tension on the cable would be set whilst the shifter was in high (3rd) gear and therefore the increase in cable tension would be limited to the final movement of shifting the last few mm in order to move the chain into top gear, sadly this didn't work either. I then tried the same method with the FD cage set over the chain whilst in top gear so that there was no additional tension required, again the shifter couldn't 'click' into position to hold the cage in place.


I then disconnected the cable from the FD and shifted into 1st, I then let the cage be pulled in by the spring so that it was back over the smallest chainring and secured the cable with way too much slack. I then applied tension by hand. This resulted in the shifter making the two shifts it's required to make. However, as I applied tension it soon became too much for the shifter and it couldn't shift into 3rd.


I've looked at the shifter for what seems like hours while shifting through the gears and cannot understand what changes in the shifter when it's under duress.


It just doesn't 'click' into position when the cable is under pressure.


I have attached a couple of photos which may be useful. I'll take more tomorrow and maybe even a link to a video on YouTube which may throw more light on the subject.

I cannot attach photos due to being new as I don't have 10 posts as yet, sorry.

Bill Kapaun

The way I do it-
Set chain on middle ring,
Screw in L screw so that the chain CAN'T drop to the small ring.
Set barrel adjuster by shifter 1 turn out from all the way in. Shifter in gear 1.
Disconnect cable
Slowly back out the limit screw 1/4 turn at a time.
Turn cranks.
Repeat until the chain just drops onto the small ring.
Clamp cable. (Pull snug with pliers etc. to take out the slack & make sure housing ends are seated correctly)
Back off L screw 1/8-1/4 turn more.
You should now have enough adjustment in the barrel adjuster to fine tune it.

Wingnuts77

Thanks for your reply Bill, sadly the result remains the same.

I've followed your instructions to the letter, several times, all with the same result.

The shifter pulls the FD far enough for the chain to go onto the outer chainring nicely, but without the shifter locking into place the chain goes back onto the middle chainring, smoothly, really smoothly. I paid particular attention to the housing as I replaced that too, just in case.

I have uploaded three videos to YouTube, here, here and here. which I hope helps, as I cannot upload photos here as I haven't posted enough times. Failing that, if you search for 'Shimano ST EF51 after initial setup with cable tension' hopefully you'll find it, and maybe be able to help me resolve this.

Thanks in advance,

Wingnuts.

Bill Kapaun

What happens if you turn the barrel adjuster in the 1 turn of travel it should have IF you followed to the letter?
IF that fails, I suspect the shifter is bad.

wesmamyke

You said the new FD was the same, so maybe not. But my first thought was the FD running out of throw, not the shifter.

Usually only something that happens when you also messed with the cranks and BB length though.

Wingnuts77

Thanks for your reply.

I have just done as you suggested, again 'similar' result. I say similar as I have been able to turn the mech in the shifter the final few millimetres with not too much force with a screwdriver. I haven't tried this before so cannot know for sure if this represents progress.

I'll keep trying everything I've learned so far and see if I can resolve this.

Any idea why the shifter works when not under duress?

Wingnuts.

Wingnuts77

You may have a point come to think of it Wesmamyke.

When I started 'playing' with this bike I did take off the crank arms and the chainrings, but not the bottom bracket, although I did take the middle and outer chainrings off the crank arm, the inner chainring was bolted separately to the crank arm. Now that I'm having such difficulty I wonder if this could be causing the problems. As far as i know the put everything back correctly.

Wingnuts.

Bill Kapaun

Fo you actually know the difference between the shifter and the FDER?
The shifter adjustment I was talking about is a knurled thumb nut that makes minor adjustments to the housing length thus adding/subtracting "effective cable length".
SCREWS are on the DER.

I think you are simply way over your head?

Wingnuts77

You're right Bill, I am indeed way over my head. Which maybe reason enough for you to quit, but that's not me.

So yes, I do know the difference between a shifter and a dérailleur, as well as the function of the barrel adjuster. That's what you're referring to isn't it?

I don't recall mentioning SCREWS.

Bill Kapaun

You mentioned using a screwdriver on the shifter.
I'm done. We are apparently in different realities.

Wingnuts77

I didn't say anything about screws though, just that I used a screwdriver to turn the mech.

dedhed

https://www.parktool.com/blog/repair...railleur-works

https://www.parktool.com/blog/repair...eur-adjustment

Andrew R Stewart 

Those who lack the ability to recognize inference or logical conclusions will have a hard time discussing involved situations. Screwdrivers imply a screw is also at play. Andy

Wingnuts77

Andy you're absolutely correct.

The tone of my reply was due to the condescending responses from Bill, which in my opinion were totally unnecessary. I should have just let it go.

I'll continue with this until it's resolved, Naturally any help offered is very much appreciated.

100bikes

Back to the issue at hand. Was the shifter you installed new or used?

From re reading the posts, I am thinking you have a bad front shifter where the "indexing or pawls or whatever
you want to call them are worn out or approaching same.

One other explanation is that the grease has congealed and not allowing the shifter to function properly.

Andrew R Stewart 

This!

And I'll add that some of the gain from asking the shop for help is that you establish a relationship with a source for more help/info and parts for the future needs you'll develop. Having a person to discuss with in a back and forth with the problem bike in front of you is so much better at discovering and learning then this keyboard and camera thing we try to do here. Andy

Wingnuts77

I've resolved the issue. As a number of you suggested it was in fact a faulty shifter, which I thought before posting here. However, having replaced both shifters with 'new' ones from eBay I thought that trail of thought had been eliminated, clearly not.
Strangely enough, I think I read something about fake shifters being sold on eBay on here actually. So when I tried the old shifter which I had cleaned out and applied new lube it worked like a dream.

I've learnt so much over the last week that I'm even more dangerous now.

So, a big thank you to everyone who contributed, I really appreciate it.