bleumeon

Hi,

I recently acquired a trek emonda alr 5. The bike was not properly tuned and aligned from the shop and I had to do it myself. The issue I have is that while the shifting on the rear derailleur is crisp and relatively quiet when on the small front chain ring when I use the large front chainring the shifting becomes slightly more delayed and not as crisp. What could be the reason causing this? I don't think its my front derailleur as I set the limits pretty carefully--what else could it be?

Thanks,
Bleumeon

dsbrantjr

A worn chain with reduced lateral stiffness will often shift relatively poorly. However if you change it, it may skip on the old cassette requiring it to be changed as well.

Front limit settings have little to nothing to do with shifting performance, since the chain does not touch the derailleur in normal operation, once it has shifted onto the chainwheel. Perhaps small (less, possibly much less than 1/8 turn) adjustments to your rear derailleur will help optimize your shifting performance. The rear limit settings basically control whether or not you spill the chain and only come into play at the extremes of the cassette.

dsaul

Is the front derailleur cable touching or crossed over the rear derailleur cable where it goes under the bottom bracket? If the front crosses over the rear, it adds friction to the rear cable when the front is shifted to the big ring. When the front is in the small ring, there is no tension on the front cable, so the rear will shift normally.

bleumeon

No crossing at all.

American Euchre

Just take it back to the shop.

A standard fix is to adjust cable tension at the derailleur. There are a gazillion tutorials on youtube.

bleumeon

I know how to adjust them myself. That is not the issue here. I tried resetting the rear derailleur many times but it always shifts a little worse when on the large front chainring.

rccardr 

Double check for correct chain length.

bradtx

The only time I had a difference in shift quality between the big and little chain ring was slooow up shifts when on the big chain ring. I adjusted the B screw a little at a time and it was sorted out. There are three differences on the RD between the large and small chain rings; angle of approach to the tension pulley, position of the RD body, and the angle of the pulley arms.

Brad

bleumeon

Did you make the b tension screw tighter or looser? I tried messing with the b tension but there was no noticeable effects. I read that you want it as loose as possible without compromising the shifting.

American Euchre

That should not be the case. There are only so many variable involved: hi, low limit, b screw, adjuster barrel.

Assuming there is no problem with the cable or housing, proper adjustment can only involve those 4 variables.

There has to be an issue with one of those 4 adjustments. Assuming you have shimano, brand new componentry should shift perfectly properly adjusted.

Also, I know how to adjust derailleurs, but I know at least one mechanic who is so much faster and more skilled, it's not worth my time to bother. I would just take it to him instead.

And yeah, as someone else said, you can check chain length.

Having said that, you're just better off taking it to the shop assuming they are reasonably close by.

I've been stubborn many times about DIY repairs and adjustments but a skilled, experienced mechanic is so much faster and more precise than I am, it's really not worth it.

bleumeon

Yeah what you say is true. I'm just a bit stingy and unwilling to drive back and forth between shops. Anyhow I redialed the rear derailleur several times, almost about to lose my insanity but its pretty good now.

Ideally I would like the shifting to be "quiet" where the chain grips the next gear immediatly after shifting but a few gears have a little delay. All in all its pretty good. For a groupset like the 105 what is reasonable for me to expect?

EDIT:

Well I tested it a bit more and I have it damn near perfect now. The issue was with my rear derailleur alignment with my high limit screw. The cog leading into the cassette doesn't sit completely in plane with the cassette gears. Because of the slight tilting I had difficulty find the best position to set my high limit in. Usually I can just use the barrel adjuster to compensate but because it adjusts the cable in fixed lengths due to detents along the barrel adjuster I could never get the derailleur exactly where I wanted it. B-tension screw wasn't set right either and I have since fixed it. I'm just happy I got it to work well, but it took more trial and error than expected.

bradtx

bkeumeon, Congratulations! Because my RD was aligned properly, I didn't think about that possibility...a pro probably would have. There was some in and out adjustment of my B screw, but overall I'd say I moved the jockey pulley closer to the largest cassette cog.

I had a 5503 group and it shifted flawlessly, I expect the same for you.

Brad

andr0id

Chain length and hanger alignment are you two usual suspects for shifts good on little ring, not so good on big ring.

By cog, do you mean the tension pulleys?

They should be perfectly in plane with the cassette. If not, your RD hanger is bent.

trailangel

My experience as well, bent hanger.

bleumeon

Hmm maybe my hanger is slightly bent or offset. Nothing too noticeable though. Next time I'm in a bike shop I'll try to look into it.

Facanh

I had two bikes in the last month with bent hangers. If the hanger is bent shifting in the rear is bad in every gear.

+1 for chain length. Even 2-3 links can make a huge difference.

But if you can see that the RD is slightly offset replace the hanger too. You need to be really precise on a 11 speed system.

bleumeon

It is common for new bikes to arrive with a bent derailleur hanger? The shifting is decent now, but there is still a tiny bit of lag on some gears that indexing won't fix. I plan to check out and tune my hanger this weekend so we'l see.

American Euchre

105 should shift perfectly. I have 8, 9 and 10 speed shimano and all shift perfectly in the rear.

I have triples with the 8 and 9 speed and the 8 speed front shifting is fast and slick. The 9 speed triple is '04 so front shifting has never been very impressive: slow and noisy. I have 10 speed double for the road and lever travel is quite long and shifts aren't super fast, but I still rate shifting as "good" as in B or B+ level shifting. I would rate ultegra 6800 front shifting as A for mechanical.

But modern 105 11 speed should be quite smooth, fast and quiet, especially for the rear. Older systems have more lever throw and a bit more of a mechanical feel and a bit more noise, but the shifting itself should index perfectly throughout shimano's line.

IMO, 105 is a tangible step or half step below 6800. 6800 is very fast, very smooth and lever travel is pretty minimal.

At the very least, take your bike back for the 30 day tuneup and get those derailleurs dialed in.

bleumeon

It's really slight. When trying to align the rear derailleur high limit screw you the tension pulley cog closest to it is ever so slightly tilted. I think the issue is a slightly misaligned rear derailleur hanger after all. Because I will be biking often, but won't have time to stop by a shop any time soon I decided to pony up the cash and bought a parks tool hanger adjustment tool. I generally prefer DIY, time permitting, so we'll see how it goes this weekend.

The b-tension screw is set right so I know its not that and I'm very careful in setting my limit screws. I've even experimented with different limit settings compensating with the barrel adjuster. Since this is a new bike, cables should still be relatively smooth and shouldn't be a friction issue--to be sure I even put some T-9 lube on the cables and derailleurs. Chain is brand new too and appears to be of right length.

EDIT:

Looking at the bike the tension pulley cog closest to the cassette is almost parallel put very slightly out of plane. The cog in the pulley above it though is even more out of plane. Its a very slight gradual arch--is this normal, just caused by some diagonal tension in the chain or for sure is this a bent hanger issue?

Facanh

An alignment tool can come in handy. Although if you want to align the hanger the wheel has to be completely true.

The RD should be completely straight.

I would still check the chain length too.

trailangel

Could you explain in more depth please.

Facanh

With an alignment tool you align the hanger against the wheel. You find multiple points on the rim and align the hanger against them. Imagine if one of those points is closer or further because the wheel is out of true. The hanger will not be completely straight. On 10-11 speed systems you need to be really precise.

Before I had an alignment tool I tried to straighten the hanger just by eye. To me it seemed completely straight, yet I could only tune the RD perfectly after I changed the hanger to a new one.

bleumeon

You can just rotate the wheel to measure the hanger at different spots. If you always use the same spot on the wheel it will always be equidistant to the hangar.

Facanh

Yeah I guess that works, didn't think of that.