kadar

Hello my first post here!

Since a couple of weeks I'm struggling with my road bike. I bought a used Giant Defy 2 (2012) a couple of years ago, haven't ridden much, and finally decided to make it alive again. I decided to replace the cassette (11-25 to 12-30) which also forced me to replace the rear derailleur. Previously it had tiagra 4600 (short cage), but decided to go one level up, and buy a new 105 5700 (long cage) derailleur. In theory and all compatibility chart suggestions everything should work like a charm, but it didn't. I kept getting those weird noises when shifting gears, the chain sometimes had troubles switching from one gear to another, and everything performed waaay worse than my second bike's Shimano Acera (which is completely silent while shifting).

The bike was at 2 or 3 bike mechanics, and this is what have been done so far:
- new cable and housing for rear derailleur
- derailleur hanger replaced with a new one
- wheels replaced to new ones (It had mavic cosmos, but the freehub was worn out and I didn't want to invest more in these wheels)
- (as mentioned) new rear derailleur
- (as mentioned) 12-30 cassette (bought a used one, good condition, about 1500km)

The problem still exists, and today I decided to measure something that I should've been done at the very beginning of my journey - the cable pull. I took a caliper, and started measuring the cable position at each of the gears. It turns, out, that the shift I have the most troubles with (shifting from 7 to 8) has the lowest cable pull (see the attachment). It results in chain "wondering" a while until it finally makes it to 8th gear.

Results (showing pull in mm between each of the gears):

1st gear
3.3 mm
2 nd gear
2.8 mm
3
2.4 mm
4
2.6 mm
5
2.4 mm
6
2.3 mm
7
1.9 mm
8
2.3 mm
9
2.2 mm
10

Is this something that can be repaired? The bike is quite old, and about 16k km, so maybe the shifter is just worn out? Is it possible that something inside is bent or broken? I'm wondering on possible solutions as I've invested quite a bit of time, and money in it, and would like to finally make it shift as it should.

Thanks in advance!
kadar

Litespud

I'm not sure that STIs are rebuildable - I'm sure they can be dismantled, but I don't know about ready sources of parts. In any case, 16k is an awfully short time for something to "wear out". You might try flushing the shifter innards with WD-40 or similar. I don't quite understand your measurements - if the shifter is "short-shifting" on the 7, why are the subsequent gears not also messed up? Surely the next shift would have to be "long" to get the rest of the gears back in line?

Iride01 

Shimano publishes the documentation to show you what to do for maintaining and disassembly. However I don't think you'll find any parts available though they do give a parts listing and part number in the exploded diagrams.

You need to look for the DM's (dealers manuals), they give the most info. I think they should have them for the models you posted about. Otherwise get the docs for the model closest to yours and they might give you enough to figure it out.

Shimano Manuals & Technical Documents

But if you aren't a DIY type that likes dealing with small parts and tedium, then just buy some new stuff.

Bah Humbug

I also think the Shimano shifters don’t pull the same amount of cable per click - isn’t that something STAM bragged about doing for a while? It might be worth seeing what the spec is by shift (but that one does stick out and look wrong).

gsa103

Try going back to the 12-25 cassette. The RD-5700 is only rated for up to 28T, so you may be having issues due to the cassette being beyond the rear derailleur spec.

canklecat

STI shifters can be rebuilt, but it's pretty involved. Here's a photo demo on Imgur showing an overhaul of Dura Ace ST-7400 shifters.

It would be feasible to fabricate some replacement parts from scratch -- steel stock milled to shape, springs, etc. -- but that's a job for someone with the tools and expertise. To borrow from gunsmithing parlance, that's the difference between a 'smith and a parts replacer.

Psimet2001 

I would place odds your shifter is fine. Even though you called it out as having been done there really aren't a lot of shops that are good at putting in new cables and housings as well as ALIGNING the derailleur hanger.

Simply putting a new one on and not taking the time to align it won't fix anything. Most frames aren't straight from the factory which is why we bend (align) new hangers.

Cable pull is non linear with Shimano. That's a rabbit hole not worth going down.

Shimano shifters are in essence non-repairable.

Honestly though it really sounds like a setup issue. Vast majority of mechanics simply only know how to set limits and only do adjustments with cable tension.

Pull the end of the cable from the anchor. Pull through all the shifts. Then while touching the end of the cable inner start to shift down one at a time. See if the inner advances on its own or with little pressure. if not then pull on the inner and see how much resistance there is in the cable.

If you have internally routed cables as well they can actually get wound around each other. I have seen more than one mechanic miss that. Quick check will be to see if everything is running well in one gear and then shift the front and see if it changes the rear's adjustment (how well it runs in the rear gear). If it changes at all then you've got your wires crossed inside.

If you were close by I would probably have you fixed up within an hour tops and be telling you for sure what the actual issue is. The odds of it being the shifter are REALLY REALLY small.

Psimet2001 

This too. I didn't dig through the specs but that 5700 - I would be surprised if it couldn't run that 30 (regardless of what they say as you can always reverse the b screw if needed) - but many mechanics don't actually understand what the b/chain tension screw is for. Also assuming you put a chain on that is long enough and that the chain is new.

kadar

Thank you guys for the links and detailed answers!

Actually for 2 chainrings in the front, the docs says that the long cage will support up to 32T. I read stories where users managed to pair it with even 34T

Well, I think you might be right. I asked one of the mechanics if the hanger was aligned, and he said it wasn't as it's new and it's not necessary to do it. Moreover, I noticed, that the derailleur moves outwards a bit after tightening the quick release, causing it not being 100% in line with the rim. I don't know if this might be the case, and it's strange as on my second bike it's 100% in line even after tightening the QR.

Ok, this is a very useful tip - you mean keeping everything routed as it is, pulling the cable from the derailleur anchor, and analysing the cable tension by switching from higher to lower cogs?

No, the cables are routed externally.

Good to hear that - I wasn't so much into buying a new shifter without knowing it will solve the issue. So from what you said, it's most probable that the issue is with the cable routing or the hanger not being aligned? Could it also be the cassette (it's not new, but I haven't heard about bent cassettes or damaged cassettes even if they look fine)

Thanks for the answers!
kadar

woodcraft

This mechanic should go on the ignore list.

robbyville

Did you say if the chain was new? 16k km isn’t much on a shifter but it is a fair bit on a chain especially if paired with a new cassette. Otherwise I’d agree with the rest sounds like an alignment challenge

kadar

Yes, the chain was new, so it shouldn't be the issue.

RiceAWay

Yes, the high level levers are rebuildable but you wouldn't want to do it. https://www.bing.com/videos/search?q...tail&FORM=VIRE As for your shift spacing, that is the common in cheap groups or those that have a lot of wear in the ratchets.

gsa103

No, the long cage (GS) does not support larger than a 28T. It has enough capacity to take up the excess chain for a 32 or 34, but that's different than the largest rated sprocket size.
https://si.shimano.com/pdfs/si/SI-5X90B-003-ENG.pdf
When you go beyond that, it sometimes works, depending on the B-screw. It can also make the alignment more finicky. Think of it this way, the upper jockey wheel is designed to always be a few mm below the cassette at a fixed distance, so it moves in a fixed path as you through the cassette. The angle of the line is fixed by the design of the derailleur and the B-screw adjusts the start of that line. As the cassette gets bigger, the upper wheel is further away from the cassette when you get down to the small gear.

I agree with Psimet that it's likely a hanger alignment issue, the shop should check, it literally take 5 minutes if you have the proper tool.

Also, a 9-speed Shimano mountain RD will properly index a 10-speed cassette when paired with a 10-speed road shifter. Many people have used that trick to run a 34T rear for extra climbing gears.

hammond9705

Agree that it probably isn’t an issue with the shifter. But if it is, I would look to buy a single shifter on eBay rather then trying to rebuild yours

kadar

Sorry, I made a mistake, because my exact model is RD-5701 GS not RD-5700 GS. It seems that in the newer version they added support up to 32T for cranks with two chainrings. At least that's what is written on the box it came in, and in the manual (I'd post a link or a photo, but I don't have 10 posts yet...)

Thanks for such a detailed info! As soon as I have the bike back, I'll try the things posted here.
kadar