Front derailleur problem for Epi...
sorry for the wordienes but i must preamble
I am starting in this forum because my problem might be Epi specific, besides you folks seem to really like to help.
As you may have guessed from my handle, i am one of those diehards that still uses top mount thumbshifters (circa late 80's). I have forayed into rapidfire twice before and was never happy. First time was original Deore DX, which were just waaay too complicated and totally not user-serviceable (60+ moving parts). Then in 2001 i tried again, with some XTR push-push shifters. This time i just could not position them ergonomically on my bars to fit with my Hayes levers....back to thumbshifters. The other thing i hated is the lack of trim capability on the front, you just cant not have the front der rub in some of the more extreme gear combos.
So with my new Epi, i decided it was time to give another shot. This time i opted for SRAM based on its good reviews. I went middle of the road x-7 (hedging my bets in case i hated it again...since the rear der is not likely compatible with my thumbshifters). The rear shifting is awesome, bang on, crisp and ergonomic. My problem is with the front der. which is an x-Gen. My crank is RF Deus with 44, 34, 22 rings. The rear is 12-32
My problem is that in the granny ring the chain rubs on the bottom of the front der cage in every gear but the easiest one (which i rarely need to use). I have lowered the front der as much as i feel comfortable (about 1 mm between bottom of cage and big chainring). I just recently noticed that if i stand to climb it stops rubbing in 2nd and 3rd, but the second i plant my ass in the saddle i am rewarded with loud grinding.
The only fix i can think of is to reduce the size of the big ring and increase the small ring.
I still hate the lack of trim capability. In order to not have the rubbing in 22f, 32r i can only use my easiest 4 cogs in the middle ring before there is rubbing (i can use the 8 smallest cogs in the big ring).
Do i just have to live with this situation? Is this as good as i can expect to get?
Thanks for reading,
over 50 years of cycling
I thought top thumb shifters were the peak of shifter design, having lived through that era. Only down side was slamming them on rocks in an endo and leaving a trail of bits.
I never have liked Rapid-Misfire in any of its variations for the reasons you state, of being too complex, plus I hate bashing my knees into them or accidentally shifting during some complex tech trail twisting.
Have you considered grip shifts? I have used them for years and being able to be sloppy about the front derailleur and trimming it as required is only one of its advantages. I also just plain like the clean look. Bairly any parts. Did I mention they LOOK CLEAN.
Otherwise its just a lot of fiddling and making sure the cage is lined up parallel and is low enough and is set correctly side to side. I am not having any problems with my new Epi with a SRAM x-gen front, but I have grip-shift and only 2 rings and a bash ring, so mine is pretty simple
Originally Posted by thumbies
I had the same problem with my Id when I tried using the SRAM triggers with the XGen front D. The problem is that the cage on the XGen is too narrow. If you do a search on XGen in the forums you should find a few good posts about this. I switched to a XT bottom swing and the rubbing problem went away. The XGen is great if you use a thumb shifter or grip shifter because they shift quicker since it has the narrow cage. Plus you can trim it with those shifters; but with a trigger shifter you can't so you need the wider cage of the Shimano.
Thanks for your input. I am hesitant to use gripshift. Partly because every shift sounds, to me, like plastic breaking
I have 3 separate pairs of thumbshifters (2 XT , 1 XC Pro) which have all been running since the late 80's. They all work as well now as when they were brand new which is pretty darn good if you dont mind friction mode. Cant beat 1 moving part.
I guess i am leaning towards putting a thumbshifter on the left to correct the trim issues. However, this does not fix my problem with the chain rubbing on the bottom of the front der. cage when in the small ring.
any other bright ideas?
over 50 years of cycling
insert light bulb here....or maybe THERE
X.9 shifter for the rear, Suntour XC-Expert front shifter on both my bikes. Works like a charm!
Ditch the front trigger, and stick one of those thumbies back on!
For the rubbing chain, either a smaller big ring, a larger small ring, or a Shimano XT front mech. Or ditching the big ring alltogether. Some pics of the front mech setup might help.
Florence Nightingale's Stormtrooper
>I DO have a several road/track bikes with components from the 70's that still work, so I can top you on that. Those were the good ole days.
Yep, you win. I'm only 32!
>Get rid of that silly Big Ring, and replace it with a bash ring. Anyone ought to be able to make a front derailleur work with only two rings.
I can't lose the big ring...i use it all the time.
>Or if you get REALLY desparate, you could try actually reading the instructions for setting up and adjusting the front derailleur.
So if I understand you correctly, the chain is sliding over the bottom of the front der cage, not hitting the sides. Sounds like scrublover has covered it, but I'll throw in my hat anyways.
My ID has this issue in some gears, but not nearly as many as you point out. It's pretty typical to some degree on all bikes with longer travel and worse with steeper seat tube (Front der mount) angles. They could make the cages longer but then some frames would hit them at the chainstay. It should be far worse on the stand when the bike is not sagged. Don't worry about what it does on the stand. If the chain is sliding over the bottom of the front der cage, then going to old school shifters isn't going to help. I see a few possibilities.
- Suspension sag may not be low enough - Should be 1/2" of the shock travel
- Front Der could be bent, not likely, but possible
- The new 44/22 front chainring spread is bad for all these der's and bikes which were designed around 42/22 chainrings. Of course you can get more clearance with 2 rings but I understand the desire for the big ring. I run 22/36 on my freeride bike and it's not as bad as I thought and I may actually try it on my ID. Of course you could also go to a 24 granny but I like the super slow turtle mode option of the 22.
- Maybe a Shimano Top-Pull Bottom-Swing der would work better. I use an XT front. Go check out the difference before you buy.
- My only other thought is that something else on the frame is out of spec, not likely, but if you post some pics of the bike including one perfect side shot we'd probably know immediately.
As a side note - I know many people who run grip shift (I like this better than thumbs personally) for the front and triggers for the rear and I can't argue that it's probably the ultimate setup. SRAM should put some extra trim clicks into the triggers just like road shifters have. BTW - when you do this all that I ask is that you please send me a few sets to use. Of course running with too much cross chain isn't good for the drivetrain anyways.
Pics of my Epi setup with X-gen front Der problem
First is a pic of the bike,
2nd shows the clearance between fron der and big chainring....less than 1mm
3rd is a top shot, attemoting to show the der alignment with the big ring. You'll have to trust me, the outside of the outside cage is parallel witht he big ring.
4th is a rear shot showing the clearance between the chain and the bottom of the front der while in 22f, 32 r. There is actually quite a bit of clearance (8 to 10 mm), in fact int he stand i can use the top 5 rear cogs before the chain hits the der (in 6th it hits the outer side plate AND bottom).
I guess there is quite a bit of difference between un-loaded (in the stand) and when the suspension is preloaded (by me). Further evidence to this is that the rubbing only happens while seated. And of course, every time i stop to check it out on the trail eveything looks fine.....
Note, this is more than a little annoying rub, its a real grinding noise which i am not too fond of when powering up the hills!
Currently i can only use 22f, 32 r, and then i have to move to 32 f, 32 r (quite a spread)
over 50 years of cycling
Oh come on now....how many people ACTUALLY read the instructions for ANYTHING.
Originally Posted by thumbies
Anyway, your follow-on post sounds like you might have "cheated" and DID read the instructions.
It does indeed sound like you have the derailleur adjusted "per spec". I think the person that mentioned proper sag might have a point. Have you checked that out yet?
Bummer about needing the Big Ring. I only have 3 rings on my Klein Hardtail Urban Assault Vehicle. Life is so much simpler with 2 rings and a bash ring.
As you can see in the bike pic, the shock is a RS MC3.3. I even read the manual for shock setup too So it is setup with the correct sag...for me at 165 lbs (with gear) that is 72 psi. The shock stroke is 51 mm and the sag is 11mm (21.5% ....the recommendation is 15 to 25%). This is set in 'open' mode (ie. no motion control/ pro pedal). I have tried going to 80 psi but the loss of plushness is dramatic.
Interestingly, the sag while standing is only 4mm and i guess its this difference that is representative of the problem with my chain grinding while seated)...Oddly 7 mm is roughly the distance between the bottom of the chain and the bottom of the der in 1st gear...this is probably just a coincidence).