I just got a used bike with a full Tiagra 4600 groupset on it and i'm having some trouble adjusting the rear mech. I'm not a complete noob, I can adjust a derailleur no problem.

It either won't shift down, or won't shift up no matter how much I play with the barrel adjuster. I can set it so it downshifts properly, but then on upshifts you have to push the lever after the click a little bit more or it won't shift up. If I set it so it upshifts properly right on the click it won't shift down.

The derailleur hanger looks straight, I just changed the housing to brand new Shimano SP41, cables are new too.

I'm pretty sure the bike got rained on a lot in it's life. The rear derailleur is full of gunk, and I can see some rust inside the shift levers. Could that be a problem?

It's a Cannondale CAAD9 frame and it uses inline barrel adjusters. Not really fan of this system, but it couldn't cause any problems right?

I'm out out ideas.

UPDATE: I took out that ugly inline barrel adjuster. It's much better now, but still sometimes it won't shift up or down. In terms of speed it's really bad. My beater bike with a Claris RD, and some random 15 year old 200GS lever shifts faster.

The most likely culprit is cable/housing friction. As the derailleur spring has to do the shift to smaller cogs if there is friction you may end up making the cable looser than it should be in order to get the derailleur to shift. Then when shifting to the larger cogs the cable is not pulled sufficiently. The new cable housing needs to be cut and capped properly and of the proper length. Certainly it does not help either if derailleur and levers are not moving freely.

...why not remove and fully clean and lubricate the rear derailleur?


I'm a little surprised to read that you took the time to replace the cabling, but didn't remove and clean the derailleur as part of the process. I'm guessing that you removed, measured and cleaned the chain, too, yes?

I used the exact same cable housing, ends, and cables on a different bike that has a 105 5600 groupset. On that bike the shifts are lightning fast and precise.

How should I clean and lube the RD? I read that spraying it with degreaser and then spraying some kind of lubricant on the moving parts is not the best thing to do. I took off the chain and cleaned it, it's not stretched, length is good. The rear cassette has been recently changed too.

There's no best way, except to fully degrease the derailleur, disassemble the pulleys at a minimum, and place the whole bunch in an ultrasonic cleaner basket. A few minutes in there and it'll be free from grit. Wipe dry and lubricate at the pivots and moving points.


By hand, you first take apart the pulley cage and spread out the parts. Use WD-40 or a degreaser and a toothbrush, small rag, q-tips, tweezers, picks or probes, and work your way around every nook and cranny. Manipulate the parallelogram to gain access to the hidden spots. Keep spraying, wiping, scrubbing, dunking and re-wiping until the surfaces are free and the pivots move easily. Re-assemble and lubricate as above.


That's what I'd do. While the derailleur's off, and if it has any bare aluminum or steel parts, you can go ahead and buff with Mother's to get it to shine. That's optional, of course. With anodizing and other finishes, don't buff, just wipe clean.

Thanks, i'll try it. I cleaned the pulleys already.

What should I use for a lubricant? Just oil? I have some grease spray thingy, you spray it on but when it dries it gets thicker, more like a super light grease.

Boeing T-9. Roger

I cleaned and lubed the RD. Not sure if I can feel any difference, I don't think it's any better.

I am really out of ideas. I don't think i'm doing anything wrong. In the past two weeks I built up 2 bikes from scratch. Both of them work perfectly, only this one is giving me trouble.

I can only think that there is something wrong with the STi.


Oh and by the way when I got the bike it did the exact same thing. The brake cables and houses were junk, so I thought the shifter cables and housings are junk too and new ones would solve the problem.

Are you certain that you don't have brake cable housing on the shifter cables? Compressed cable housing could cause that.

Nope. It's Shimano SP41 teflon shifter housing.

You might try alternate cable routing on the DR - closer to the pivot to increase the amount that the DR moves on the click.

Have you played with the B screw adjustment? Sometimes, a "non standard" adjustment might work when the proper adjustment doesn't.

Are you by chance using a "mountain" cassette instead of "road"?

I set the b-screw to the correct spec but i'll try to play with it. The bike has a 105 cassette.

I still don't get why a fully stock groupset wouldn't function properly... I'm pretty sure it's the shifters. The levers don't move and sound as good as they should.

If the shifters are well working then new cables/housing and aligning the rear hanger usually fixes it.

Don't have a DR hanger alignment tool sadly, but it looks okay. I had 2 bikes with bent hangers in the past, and before replacing the bent hanger it was always super hard to shift up to the larger cogs in the back. On this bike I don't have that problem and the hanger looks straight, but I might take it to may local shop to check it.

That would be my candidate for second most likely culprit.

On a used bike my vote for most likely culprit (by a wide margin) would be derailleur hanger alignment.

As I said the cables and housings have been replaced. When I had bikes with bent hangers only a few gears wouldn't work properly, and it was always really hard to shift to the larger cogs at the back.
On this bike the shifting is bad in every gear and it's easy to shift to the larger cogs.

Shimano road 10 speed groups are the worst to set up.
Tight cog spacing that gives problems in case of the slightest bend of RD hanger, or any misalignment,
combined with the shortest cable pull per gear change of all the groupsets of all the manufacturers I've known - so any cable friction, or housing compression can give you problems.

Having said that, with good cables, housing and proper routing, it can be made to work - but you need to do it all right.

- Chain and sprockets not worn (stretched)
- Proper cable routing
- Decent quality cables and housing (SP41 is good)
- RD hanger needs to be perfectly straight
- RD needs to be properly set up, of course
- After cabling and setting up, give it some time to bed in and fine tune it again

For MTB, as well as for 11 speed, Shimano increased the amount of rear shifter cable pull per gear change. Also, the new Tiagra 4700, also 10 speed road, has increased cable pull and is not compatible with the older 10 speed stuff (shifters and RDs aren't compatible).

Flush out your shifter with wd40 then relube although I don’t think this is your problem, if it were me I would check the r/d hanger with the appropriate tool if that fails then its new chain and cassette time.

The chain looks perfectly good, cassette has been changed recently, and it worked in another bike i've got. I think the routing is okay.
I'll take it to my local shop to check the RD hanger but it looks okay.

Not trying to show off, road bike maintenance is not rocket science after all. In the past 2 weeks I set up the derailleurs on two 10 speed Shimano roadbikes in a few minutes, both of them work perfectly. One had a bent RD hanger and even on that the shifting was so much better than on this bike.

I might try to clean and lube the shifters although i'm a little afraid to do that, i'm pretty sure it's not the proper way to do it. But I don't want to dissasemble Shimano shifters to clean and check them so that might be the only way.

might try to clean and lube the shifters although i'm a little afraid to do that, i'm pretty sure it's not the proper way to do it. But I don't want to dissasemble Shimano shifters to clean and check them so that might be the only way.

Its by far the best way, I have brought back many a shifter/brifter from the dead with the flush and lube technique I remove the shift cable and work the shift levers back and forth thru the clicks, usually when your shifter gums up it starts loosing that crisp click sound you havent mentioned this so I dont think its your shifter? you could chuck on the casstte and chain from your working like a dream 105 set up to rule those 2 components out(or vice versa)

As far as routing goes, this can also make a difference - I do it this way always (in case you haven't done that already):

I tried the wheels from this bike in my 105 bike and the shifting was perfect, so it's not the cassette. Chain is not streched either.

As I said I see a lot of gunk, and a little bit of rust in the shifters.

I'll try "California Cross".

I've had two bikes recently where the front derailer seemed frozen. I couldn't budge it even pressing hard on the shifter. Turned out to be Only gunk in the plastic cable guide under the bottom bracket. Amazing how much friction some dirt can create.

The voice of intelligent common sense.