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Old 08-21-07, 06:39 AM   #1
unksme
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not enough front derailleur reach?

Hi,

I'm working on my Univega Gran Turismo. I've just put on a new XD600 triple crank with a UN73 68x113 BB. Now I'm trying to adjust the Mountech front der. I'm stuck. If I pull the derailleur out as far as possible (until the lock nut hits the seat tube clamp) and bring the derailleur as low as possible, I can just barely get the chain onto the big ring. With the der. that low, when I bring it in for the small ring, it interferes with the above-the-bottom-bracket rear derailleur cable, and causes a rear upshift. Doh! If I bring the der any higher, it doesn't even make it to the big ring (and I should be able to get past it a bit and then trim).

So, I'm stuck and thinking about options...: shorter BB, new front der, bending current front der.

The big ring presently looks to be about 57mm from the center of the seat tube; that seems reasonable to me, so I think my derailler is being deficient. What would be the best cheap replacement? I've already bent out the bolt on the current derailler a bit, but I don't think I can go further to clear the clamp completely (and I think something else would limit the swing at that point anyway).

Also, it looks like I could fit a penny between the drive side crank and the end of the taper on the spindle, would a 110 or 107 spindle work? Where, exactly, do they get shorter?

Thanks for any advice.
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Old 08-21-07, 06:49 AM   #2
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I think a road type front derailleur would solve your problem. I have several different models in both Shimano and Campy and the actuating arm can pivot all the way in and never touch the mounting clamp on any of them. Look for a 105 or Tiagra as they will be relatively inexpensive and, despite the "road" designation, will shift fine with a 48T large chainring.

You have discovered the problem of above-the-chainstay cable routing when using smaller "big" chainrings. I had a mid-80's Bridgestone and had the same problem when I wanted to replace the OEM 52T big ring with a 46T. The tail of the fd hit the cable when I adjusted it to the proper chainring clearance.
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Old 08-21-07, 07:07 AM   #3
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It does seem odd that the Mountech FD won't work properly. Touring bikes from the '80's with cranks very similar to your XD600's are exactly what the Mountech was made for. My '83 Centurion Pro Tour came stock with a Mountech FD. But hey, if doesn't work, it doesn't work. Do what you gotta do-
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Old 08-21-07, 07:17 AM   #4
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I am perplexed by the problem with the Mountech as well. The Sugino crank I'm replacing (because I broke it) is very similar to the Sugino XD600 I'm installing; so I thought the Mountech would have no problem getting out to it. I think the bigger problem may be the change from the open bottom bracket to the new cartridge BB. The 113 spindle was suggested for the XD600, but I've got 6 speed, 126mm rear spacing and plenty of clearance for the crank itself to move closer to the frame. I suppose I could take it apart and re-assemble with the old BB to check the derailleur and chain line; but that seems like a lot of work when it isn't a configuration I wan to stay with.
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Old 08-21-07, 07:24 AM   #5
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Originally Posted by unksme View Post
I am perplexed by the problem with the Mountech as well. The Sugino crank I'm replacing (because I broke it) is very similar to the Sugino XD600 I'm installing; so I thought the Mountech would have no problem getting out to it. I think the bigger problem may be the change from the open bottom bracket to the new cartridge BB. The 113 spindle was suggested for the XD600, but I've got 6 speed, 126mm rear spacing and plenty of clearance for the crank itself to move closer to the frame. I suppose I could take it apart and re-assemble with the old BB to check the derailleur and chain line; but that seems like a lot of work when it isn't a configuration I wan to stay with.
It sounds like your chainline is too far outside with the 113mm spindle and the XD cranks. I think it would be worth it to put a cartridge bb on there with a shorter spindle, probably 109mm. This will probably allow the Mountech FD to work properly as well as give you the proper chainline-

P.S. I wouldn't assume you can put the old bb spindle that worked just fine with your old Sugino cranks on there and get the proper chainline with the XD's. My experience with Sugino triple cranks from the '80's is that they require unusually long bb spindles. I think the Sugino AT cranks on the Centurion I mentioned uses something like a 127mm bb spindle, for example-

Last edited by well biked; 08-21-07 at 07:41 AM.
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Old 08-21-07, 07:59 AM   #6
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I'm not familiar with the Mountech FD, but I assume it has limit screws like all other FDs? Did you check them to ensure that you're using all available derailleur travel?
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Old 08-21-07, 08:18 AM   #7
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Yep. My limit screws are not limiting throw/reach. The cage arm swing is limited, I think, by the lock nut grinding against the clamp or (it is hard to tell) the arm itself running into the spring on the clamp side on the fulcrum bit.
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Old 08-21-07, 08:20 AM   #8
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Is your drive side crankarm fully pressed on? You might need to torque that puppy on some more.
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Old 08-21-07, 08:26 AM   #9
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It sounds like your chainline is too far outside with the 113mm spindle and the XD cranks. I think it would be worth it to put a cartridge bb on there with a shorter spindle, probably 109mm. This will probably allow the Mountech FD to work properly as well as give you the proper chainline-
Which is disappointing... I like to follow directions (like the ones with the XD600 crankset) and have the result be as anticipated.

But, restating part of my original post:

Quote:
Also, it looks like I could fit a penny between the drive side crank and the end of the taper on the spindle, would a 110 or 107 spindle work? Where, exactly, do they get shorter?
If I have a couple of mm of clearance on the drive side now between the crank itself and the non-tapered part of the current UN73 spindle, will a shorter BB be shorter in the right places? If I stick with shimano, will a 110 or 107 be a bit shorter on the drive side? Will the protruding parts of the BB (not the spindle itself) be appropriately recessed?
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Old 08-21-07, 08:41 AM   #10
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Originally Posted by unksme View Post
Which is disappointing... I like to follow directions (like the ones with the XD600 crankset) and have the result be as anticipated.
It's not always as cut and dried as this, because there are things that vary from frame to frame (diameter of seat tube, for one), but I believe the common spindle length recommendations for that crankset are MORE OR LESS based on modern dropout spacing (i.e. 130mm or 135mm spacing). The 113mm with the XD's is GENERALLY for 130mm spacing, and the other common recommendation, 118mm, is GENERALLY for 135mm spacing. So it stands to reason that your bike with 126mm would LIKELY require a shorter spindle to get the proper chainline. Again, these are VERY general statements. But because of the problems you're having and the other things you describe, what seems almost certain is that your 113mm bb spindle, with those cranks and your frame, is too long. How much too long, exactly, is impossible to say from where I'm sitting.

Last edited by well biked; 08-21-07 at 11:03 AM.
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Old 08-21-07, 09:15 AM   #11
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Is your drive side crankarm fully pressed on? You might need to torque that puppy on some more.
I'm too lazy a mechanic to get out a torque wrench; but the darn this is on pretty darn tight using a long allen wrench on the supplied crank arm bolt. With the taper of the spindle, I don't thing more torque is going to get me a few mm.
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Old 09-14-07, 01:08 PM   #12
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Two notes to close up this thread if anybody ever has a similar problem.

1) My mountech FD seems to have been modified a bit. Pictures I've seen of this derailleur on ebay don't have the nylock nut that I have on the cable securing bolt. However, I don't think the nut is really limiting the travel.

2) a 68x107mm BB works for me if I leave a few mm between the drive side "cup" and the bb shell. As I mentioned in the OP, I couldn't get my chain on the big ring (46t!) with the 68x113 UN73 flush against the shell. With a 68x107 (UN54), if I secured it flush, I couldn't get my chain onto the granny. I split the difference and tightened up the 68x107 with a gap of a few mm on the drive side. I suppose a nice feature of the UN54 is that the non-drive ring has no shoulder lip, so the BB itself is a bit adjustable. I didn't try a 68x110, because my reading indicated that it the same length as the 113 on the drive side (couldn't find the best docs on that).
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