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Apex Derailleur -----> Dura Ace 7900

1K views 18 replies 9 participants last post by  xeon 
#1 ·
My Trek Speed Concept came with Apex components and it shifts okay... but coming from a 105 drive train, a bit clunky in comparison. So I've been thinking about drive train upgrades and I'm to the derailleur. Was thinking about using a Force or Red but the Dura Ace seems to be awesome and a decent buy especially as compared to Red. I run PG-1050 and PG-1070 11-28 cassettes.

Any issues here... other than getting much better shifts by going to the DA 7900?

TIA
 
#2 ·
You can't just swap out a SRAM RD for a Shimano RD, they aren't compatible. You need to swap out the shifters + RD if you want to go to Shimano (at the minimum).


Changing the rear derailleur isn't going to do a whole lot for you anyways. You're basically just paying for lighter weight and maybe better spinning pulleys.
 
#3 ·
You're right... found this:

Sram Shifters pull about 3mm cable per shift
Sram derailleurs move at a 1.3:1 ratio

Shimano shifters pull about 2.35mm cable per shift
Shimano derailleurs move at a 1.7:1 ratio

Campy 10 speed shifters pull a varying amount between 2.5mm-3.25mm
Campy derailleurs move at a 1.5:1 ratio

So it looks like I'd have to at least replace my shifters if I went this route. I learned something and thank you.
 
#7 ·
Yeah I'm thinking I need to just spend some time adjusting the rear derailleur. Shifting isn't great, i.e. a click doesn't equal a shift, sometimes skips a gear shifting up or down and I have some noise in the middle of the cassette... I think coming from my jockey wheels.
 
#8 ·
Sounds like it isn't set up right, as opposed to faulty equipment. 10 speed can be finicky.
 
#9 ·
I'm leaning toward the not set up right theory as well. Will be tuning it and see if that improves things.

BTW, in reading up on SRAM rear derailleurs it doesn't look you get much of anything other than reduced weight as you move "up" the line.
 
#10 ·
Don't forget to have the derailleur hanger checked to make sure it's aligned properly. With the spacing getting smaller and smaller between gears, it's more critical that it's aligned properly to aid in shifting and to reduce noise.


Sram does have a more mechanical feel than Shimano. Sram kind of drops precisely into the next gear as opposed to sliding into the next gear.
 
#11 ·
Will do... in checking and tinkering it with it last night I found that my rear derailleur was switched by my shop to a Rival. It was in for a shift cable replacement. I noted the H was way out and I tuned that in, a little bit of the L and now I've got noise on the smallest gear similar to what I had in the middle of the cassette.

It seems to shift better now although shifting down from 50-28 isn't so hot... but I shouldn't be cross chained like that anyway.

You all are awesome btw, thank you for bearing with me as I learn how to be a better bike wrencher.
 
#12 ·
Why did you adjust the limit screws as opposed to the barrel adjuster? Limit screws do not really impact shifting. They adjust the inner and outer limits of the derailleur throw and are really there to keep you from throwing the chain into the spokes behind the cassette or between the cassette and the frame. Barrel adjusters are used to adjust cable tension and actually impacts your shifting performance. You can mess with your barrel adjuster all day and just muck up or refine your shifting. Messing with limit screws can result in some pretty serious damage to both the drivetrain and wheels if done incorrectly. You should not mess with the limit screws unless you have some idea what you are doing, they do not adjust shifting performance.
 
#13 ·
I watched a youtube vid on SRAM derailleur adjustment and tuned the H just a smidge to the outside of the cassette and the same with the L towards the spokes. I tightened the range of movement on both sides actually, so if it didn't fall into the spoke or off the cassette before it for sure will not now. :)
 
#15 ·
What I'd do is simply start from step one in the installation and adjustment instructions for Sram RD's. Unless you're totally comfortable with diagnosing and adjusting RD issues, it's always best to start at the very, very first step and follow each and every step. H, L, B, cable tension (barrel) are all inter-related and you won't make any progress if you just dink around here and there - again, unless you're very comfortable knowing exactly what's causing the problem.
 
#17 ·
This is essentially what I did and when I got done I noted the noise on the small chain ring and it didn't shift very well off of the 28 on the other end of the cassette... not that I run that gear anyway.

I went for 30 mile spin and it shifted and sounded great under power. That noise in the middle of the cassette is gone. It isn't hard to wrench on these if you go step by step.

Not sure about the H though, when I draw it up like the instructions seem to say it makes noise and shifting worse... I've left it essentially where my shop had it, otherwise I tightened the H and L like I said and dialed in the indexing with the barrel. Rides and shifts great, not much drive train sound. A little chain rub at 50-11, otherwise :D
 
#16 ·
I went from a shimano 105 to a sram apex as well. I have not found any issues with the apex shifting to the right gears. Compared to the 105 I find the shifting on the apex more positive and mechanical feeling to it. I do find the Sram noisier, but I think that has to do with the chain.

I think your issues are really just about getting it adjusted correctly. Do it step by step from the start. If you are still having problems, it may be a bent deraileur/hanger or a loose cassette.

Regardless of which groupset you use, it should all do the same thing. Every click you make should shift a gear. Some may be smoother than others, but it should all provide the basic functions.
 
#18 ·
Considering you put your bike in the shop for new cables and got a new rear derailleur, some of your shifting problems may be from your cables/housing. I'd go to a different shop (1st shop has already proven untrustworthy), and have new cables and housing installed and a full tune up, and explain to them why. Since you're new to doing your own wrenching, this particular situation is, for you, like fighting with one foot in a bucket.

Go to a different shop (if one is available) get your bike to a known 'good'. Then you can learn without having to diagnose problems you didn't even know you had.
 
#19 ·
I can't say I disagree with you but the shop in question sponsors me. The shop owner and I should probably chat about it. My initial issue was creaking cables and (supposed) the cables were twisted up around the cable adjuster area when I moved the handlebars left and right.

My tuning sure did improve things, not sure it has ever shifted this well honestly now that I've ridden it a few times. I think I'm good and the noise I was hearing after I tuned... it isn't there.
 
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