Results 1 to 18 of 18
  1. #1
    mtbr member
    Reputation:
    Join Date
    Oct 2006
    Posts
    208

    Caution;  Merge;  Workers Ahead! Caution...warning to Epiphany owners

    I thought that this issue was important enough to start a new thread for those of you who havent been following my front derailleur woes.

    Cutting to the chase....Twisted Trail and i independently determined that there is a high likelyhood that your front der may contact you right chainstay under full compression of the rear suspension if your front derailleur is mounted within the specs (laid out in your der setup manual).

    By my calculations, the distance between the bottom of the front der and the top of the right chainstay should be no less than 29 mm.

    I checked this by deflating my shock and compressing the suspension...in my case at 26 mm, the front der hit the chainstay 3/8" shy of full travel (5.25 ").

    It is very easy to check if you have this incompatibility problem. Simply measure the distance between the bottom of your front der and the top of your chainstay when you are in the small chainring. Twisted trail also noticed that there is very little clearance between his front der and the chainstay pivot.

    The only solution is to raise the front der although this may affect your shifting performance.

    For more information, you can check out this thread:
    Front derailleur problem for Epi...solved

    I am curious to see other Epi owners' comments and i would sure like to hear what Ellsworth has to say about this.

    Thumbies

  2. #2
    over 50 years of cycling
    Reputation: Twisted Trail's Avatar
    Join Date
    Oct 2006
    Posts
    533

    Bonking ... not feelin' well clunk ouch clunk ouch D'oh!

    I will confirm thumbies observation, unfortunately.
    I ended up with 30mm from chainstay to bottom of fr derailleur cage using the deflated shock test, but I might like a bit more margin than Thumbie likes at 29mm.

    note that Thumbie has installed a Shimano and I have a SRAM Xgen front derailleur, so we even managed to cover some variety in this. I think we have discussed "proper setup" of the derailleur enough to rule out THAT possibility (sorry, about my remarks thumbies!)

    Depending on exactly where you have your derailleur, finding this problem requires having it in the small ring and either hitting a small bump, up to a big hit.

    I am running a bash ring and was running the setting straight from the shop, which was pretty much to spec. First trail ride picked up the problem when the first couple of bumps ripped a chunk out of the frame with the changer cage. (OK, it shaved off a tiny spot....but hey, its the first ding so it FELT huge.)

    I raised it up on the trail and fine tuned it when I got home. The rest of the ride was like butter. Shifting seems to be ok, but with only two chainrings it doesn't take much to knock it back and forth.

    Good idea to make a separate topic. I was debating that myself. Its painful to see the glint of raw aluminum where it should be black anodized, no matter how small the spot!
    Live in the moment.
    YMMV

  3. #3
    mtbr member
    Reputation:
    Join Date
    Feb 2006
    Posts
    158
    Hey guy's,

    Just checked mine out...no issue that I can see. I didn't do any measuring, but I did shift the Fnt Der. into the granny and fully deflate and compress the shock. The cage is close, but not alarmingly close. I carefully inspected the chain stay for any signs of previous contact and didn't see a thing. I've pounded the bike pretty good while riding in the Granny ring, so if I had a problem with clearance, it definitley would have shown up I think.

    The Epi has been around long enough, it seems this prob would have been discoverd/mentioned by now.

    FWIW, I have an XTR Fnt Der.

    Good luck!

  4. #4
    over 50 years of cycling
    Reputation: Twisted Trail's Avatar
    Join Date
    Oct 2006
    Posts
    533
    Quote Originally Posted by RACERX70
    Hey guy's,

    Just checked mine out...no issue that I can see. I didn't do any measuring, but I did shift the Fnt Der. into the granny and fully deflate and compress the shock. The cage is close, but not alarmingly close. I carefully inspected the chain stay for any signs of previous contact and didn't see a thing. I've pounded the bike pretty good while riding in the Granny ring, so if I had a problem with clearance, it definitley would have shown up I think.

    The Epi has been around long enough, it seems this prob would have been discoverd/mentioned by now.

    FWIW, I have an XTR Fnt Der.

    Good luck!
    I am not sure which model of Shimano Thumbie ended up using.

    Do you have any way to accurately measure the clearance distance from the chainstay to the bottom of the der cage with shock inflated and in small ring? That would be interesting for comparison.

    You might have been lucky and had it "too high" to begin with.

    This is a time when it pays NOT to be running a component tightly to spec.
    Live in the moment.
    YMMV

  5. #5
    anc
    anc is offline
    mtbr member
    Reputation:
    Join Date
    Aug 2006
    Posts
    34
    Checked my XTR mech last night, no clearance issues. I've got the mech as low as possible(2mm clearance on the big ring) to avoid the chain rubbing the cage in granny the ring.

  6. #6
    mtbr member
    Reputation:
    Join Date
    Oct 2006
    Posts
    208

    a little clarification...

    Racerx70 and anc,
    I only noticed the potential for front der contact after i fully deflated my shock, it does not appear to have hit yet while riding. I guess i haven not yet bottomed out the rear travel.

    I think it is safe to say that it is not enough to just look at you bike and check for damage, It may also not be enough to deflate your shock and try to fully compress the suspension (unless you actually measure rear wheel travel, like i did....otherwise, how do you know if you really fully compressed).

    If you did, in fact fully compress your suspension, Racerx70, what was the limiting factor? did the shock bottom out or did the carbon swing link brace contact the seatpost?

    Again, the easiest way to check for a problem is to measure the distance between the bottom of the front der cage and the top of the chainstay while in your small ring. I have attached a picture to clarify (note, in this pic the front der is setup for about 2 mm clearance between the der and the big ring, however thehre is only 26 mm clearance between the bottom of the cage and the chainstay). By my calculations, this distance myst be a minumum of 29 mm when the suspension is un sprung....30 or 31 mm would give some clearance.

    It would appear that, to meet this constraint, the front der must be elevated higher than spec.

    ANC, if you measured only 2 mm clearance between the der cage and the big ring, you likely do not have anough clearance between the cage and the frame for full travel. Of course, however XTR may be different ... at this point we only have 2 samples: an X-gen and an older LX.
    Attached Images Attached Images

  7. #7
    anc
    anc is offline
    mtbr member
    Reputation:
    Join Date
    Aug 2006
    Posts
    34
    I'll double check it tonight, I thought the shock was the limiting factor. Perhaps I didn't deflate it fully. The cardon brace wasn't too near to the seat tube(more than 10mm from memory), should it be?

  8. #8
    mtbr member
    Reputation:
    Join Date
    Oct 2006
    Posts
    208

    limit of travel...

    Quote Originally Posted by anc
    I'll double check it tonight, I thought the shock was the limiting factor. Perhaps I didn't deflate it fully. The cardon brace wasn't too near to the seat tube(more than 10mm from memory), should it be?
    I'm not sure that you can depend on deflating the shock and trying to fully compress the suspension to check the front der...what if you did not fully compress for some reason?
    Measuring the clearance seems to be simpler and more accurate.


    actually, I think my question was silly really, there's obviously a bottom-out system built onto the shock...whacking carbon bits onto aluminum bits would be a bit of a design no-no. I really dont know what i was thinking.

    I am still very interested to see some others try to measure the amount of rear travel they get...to see how close they get to the 5.25"



    thumbies

  9. #9
    over 50 years of cycling
    Reputation: Twisted Trail's Avatar
    Join Date
    Oct 2006
    Posts
    533

    Caution;  Merge;  Workers Ahead! ONLY XTR front derailleur compatible ?

    Quote Originally Posted by thumbies
    I'm not sure that you can depend on deflating the shock and trying to fully compress the suspension to check the front der...what if you did not fully compress for some reason?
    Measuring the clearance seems to be simpler and more accurate.


    actually, I think my question was silly really, there's obviously a bottom-out system built onto the shock...whacking carbon bits onto aluminum bits would be a bit of a design no-no. I really dont know what i was thinking.

    I am still very interested to see some others try to measure the amount of rear travel they get...to see how close they get to the 5.25"



    thumbies
    Maybe Epi's are ONLY "XTR compatible" for the front derailleur? I will have to see if I happen to have an XTR on the front of one of my other bikes, although I doubt it because I usually don't worry much about the front derailleur since I have twist grips and just about anything will work......usually. But then I have never had a problem with the front derailleur trying to eat the frame.

    When I was deflating my shock for checking minimum clearance, I made a note of where the top of the rear tire would have to be for 5.25" clearance. It definitely was NOT that much travel with my Fox Float R, when it bottomed out on deflated piston travel. I did NOT check EXACT travel although noted it was APPROX 4.5 or a probably bit more. Which I am not worried about max travel since it feels like a lot anyway, after coming from a quasi-hardtail Specialized Epic, and for me the choice of Epi was more about overall geometry and handling, a balance between robustness and weight, and its puuurty.
    Live in the moment.
    YMMV

  10. #10
    anc
    anc is offline
    mtbr member
    Reputation:
    Join Date
    Aug 2006
    Posts
    34
    Right checked it again, I've got a 30mm gap from the cage to the chainsay with a 2-3mm gap on 44 big ring. So it looks like the XTR mech is ok for clearance.




  11. #11
    over 50 years of cycling
    Reputation: Twisted Trail's Avatar
    Join Date
    Oct 2006
    Posts
    533

    Cool-blue Rhythm I'm ok

    It sure looks like XTR front is the ONLY way to go for compatibility with the Epi.
    anc's pics pretty much confirms it.

    I am really NOT an employee or affiliated with rbikes.com, where I just bought my new Epi, I am just a REALLY happy customer of theirs.

    They felt really bad about not catching the interference issue with my frame and the SRAM xgen, and the resulting ding, even though I do NOT hold them at fault for this freakish incompatibility problem that is hard to track down.

    They are sending a NEW XTR front derailleur to take car of the problem for me, even though I insisted I was ok with the high riding SRAM.

    rbikes.com has exceeded any or all Customer Service expectations I have EVER had at my LBS available in my area. I was worried about buying a bike "mail order" for the first time. These guys more than make up for the distance. The owner Mike was on the phone to me as soon as he got back from his weekend and found my "heads up" e-mail warning him of this issue for his future Epi builds, and I hadn't even requested him to do anything for me.
    Live in the moment.
    YMMV

  12. #12
    mtbr member
    Reputation:
    Join Date
    Nov 2006
    Posts
    5
    Hey guys,

    Are you sure your Front Derailers are being set up right in the first place? Please PM me with your email address and we'll figure this out. Many of us here run the epiphany with a SRAM X-Gen with no problem. Thanks!

  13. #13
    mtbr member
    Reputation:
    Join Date
    Oct 2006
    Posts
    208

    X-gen incompatibility...

    Hello Kurt,
    Thanks so much for responding to this issue.

    I dont know what 'PM' means but i will email this post (which is basically a reiteration of past posts) directly to you as well.

    I am running a RF Deus crank with 44, 32, 22 rings. Front and rear shifters are x-7 as is the rear der. I had started with an x-gen front der but switched to an older LX ( 2002 i think) because of rubbing issues in some gear combos. Most front der specs suggest about a 2- 3 mm gap between the bottom of the outside cage and the big ring (see attached pic...taken directly from the x-gen der setup guide). However, in my experience with X-gen and LX, if you set the der up according to this spec, it only leaves 25 to 27 mm of clearance between the bottom of the front der cage and the top of the chainstay.

    According to my in-the-garage testing, where i was trying to measure the actual travel of the rear suspension, my front der would bottom out on the chainstay at 4.875 " (124 mm) through the travel. There are no marks on my chainstay, so i guess i have yet to go that deep into the travel, but the potential is certainly there, which Twisted Trail has aptly demonstrated.

    According to my quick math, to get the full 5.25" of travel, the clearance between the front der and the chainstay must be at least 29 mm, which pushes the front der up, out of spec. I have pushed it up to 30 mm but it has definitely negatively affected my shifting performance.

    The most recent MBA issue has an article about der setup and uses an Epiphany with an x-gen as a model in the pictures. If you look closely, the clearance betweent he front der and the big chainring looks to be about 7-8 mm....Ironically, considering the title of the article, this is way outside the X-gen spec.......i wonder if the chainstay clearance issue is the reason why?

    Since you say that you have been using the x-gen no problem, i would like to know the clearances that you folks have:
    1. bottom of cage to top of chainstay
    2. outer cage to big-ring

    Furthermore, when i removed the front der, and fully compressed the shock (leting air out of the schrader as i went), i could still only get 5" of travel. Perhaps the missinf 0.25" is related to the bottom-out bumper inside the shock.

    I look forward to your response,
    Thumbies
    Attached Images Attached Images

  14. #14
    mtbr member
    Reputation: baha_boater's Avatar
    Join Date
    Oct 2006
    Posts
    170

    I guess I got lucky

    Either whoever built my bike knew of this issue or he did not know how to setup a front derailer. FYI... I have the Sram XGEN which has been identified as a problem....

    The best way I can see to check the height of the derailer is to shift into the small chain ring, let all the air out of the rear shock and set the bike on the floor and GENTLY lean on the seat with your upper body closely watching the clearence as the rear suspension compresses. Using this method it is easy to determine the distance between the bottom of the cage and the swing arm at full compression and adjust if required (while allowing for different size frames/chain rings etc). By the way my front derailer works just fine even though it is higher than spec by quite a bit..

  15. #15
    mtbr member
    Reputation:
    Join Date
    Oct 2006
    Posts
    208

    measuring clearance...

    You are correct, baha_boater, deflatign the shock is a good way to test, but it is way easier to just measure the distance from your der (while int he small ring) to the top of the chainstay (like in pics of previous posts).

    BTW, how high is your der ?

    Thumbies

  16. #16
    mtbr member
    Reputation: baha_boater's Avatar
    Join Date
    Oct 2006
    Posts
    170
    thumbies I am glad to check.... Would you like me to measure from the big chain ring to the bottom of the cage or from the swing arm to the rear of the cage?

  17. #17
    mtbr member
    Reputation:
    Join Date
    Oct 2006
    Posts
    208

    both....

    the latter lets you know if you have enough clearance for full travel,
    the former speaks to whether your front der is within spec fromt he manufacturer.

    thumbies

  18. #18
    bwc
    bwc is offline
    mtbr member
    Reputation:
    Join Date
    Sep 2005
    Posts
    9
    I have a med Epi with a SRAM X-Gen front der. Clearance is 33mm and the der. does not look abnormally high.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •