Bicycle Mechanics - Front Derailleur and Water Bottle Bosses

Hi,

It seems that a replacement road bike frame I just got has a water bottle boss right where I need to clamp on the front derailleur. Is there a way around this problem? I've been searching and I'm coming up empty.

If anyone needs a picture, I can go take one. Currently, the front derailleur is sitting very high and I doubt it would shift well in that position.

Thanks!

If you can get new bottle cages, get something like Tacx Tao, there is no material between the two cage bolts where you derailleur band can fit.

http://probikekit.com/display.php?code=A1149

Thanks for the reply, but I was hoping to move the derailleur clamp down more so that the front derailleur would be closer to the chainrings for better shifting. Is there a way I can remount the front derailleur lower?

A picture would help. Perhaps if you remove the bottle mounting bolt, the remaining profile of the boss will be low enough for you to mount your FD.

When this happened on my frame I changed the derailleur style from top swing to a bottom swing. This moved the clamp band above the lower water bottle boss for the same derailleur height. Then I used the TACX TAO cage as mentioned above to finish the job.http://www.jensonusa.com/store/imgWrapper.aspx?img=/fd/FD311A00_____35.0_TOP.jpg&type=2 (http://www.jensonusa.com/store/product/FD311A00-Sram+X9+Front+Derailleur+07.aspx#)

Here are some pictures... it looks like if the band is on the water bottle boss, then the front derailleur would sit just above the outside chainring. It's a compact crank.

I like the down swing idea, but it was for a triple crank. Any other suggestions?

http://www.austinfang.com/pictures/jamis/IMG_2909.JPG
http://www.austinfang.com/pictures/jamis/IMG_2910.JPG
http://www.austinfang.com/pictures/jamis/IMG_2911.JPG

It would appear that you have a bit more problem than it appeared at first.

1. That's a small frame at 48cm and they traditionally have seatpost water bottle problems.
2. You are correct that virtually all road derailleurs (a double in your case) have about the same cage to band height.

I notice that your derailleur is a braze on style however. It may be possible to get a different clamp band/braze on adapter with a longer adjuster slot that would allow the band to be mounted higher or lower and still fit the chain ring. It is not uncommon to hear that riders have had to elongate the mounting slot downward on a regular braze on to accomodat the smaller chain ring of a compact double.

Thanks for the quick response. I was also thinking that I might have to go with a special machined part that might be an "adaptor" between the braze-on FD and the band clamp. Maybe I can mill and drill out an aluminum part and tap the correct threads. I just hope in doing so, that the FD can still be stiff enough to operate properly.

Thanks again for the confirmation and insight!

So, would putting the FD clamp below the water bottle boss make it too low? Hard to tell from the picture, but it looks like there might be enough room.

It looks waaay too high on the seat tube. But, you know that.

Yeah, unfortunately, putting it right below the lower water bottle boss makes the FD hit the large chainring teeth. It's really like 2-3 mm. Soooo close... if you guys have any other ideas, please let me know!

Thanks!

So, would putting the FD clamp below the water bottle boss make it too low? Hard to tell from the picture, but it looks like there might be enough room.

I was wondering the same thing. looks like there may be juuuust enough room. If not, Id just notch the band a little until it fits. Its really looks like it may be close enough to move below that boss.

If you remove the cap screw from the lower waterbottle braze-on, can the fd's bracket go around the remaining threaded boss?

Yes, it can, but I don't know how stable it is. I feel like if I tighten the clamp, it will crush the boss and crack the frame. Maybe I can try to put a piece of rubber between the clamp and the threaded boss to take up the slack and soften the surface.

Get a dremel and remove some material from the top of the band where it hits the boss? Perhaps this would give you the room you need to put the band below the boss.

Go to your LBS that carries Giants. My OCR3(small) actually had little spacers attached to my water bottle bosses to clear the brazed on front derailleur. Better than trying to grind your bosses.

Yeah, unfortunately, putting it right below the lower water bottle boss makes the FD hit the large chainring teeth. It's really like 2-3 mm. Soooo close... if you guys have any other ideas, please let me know!

Thanks!

How about a new band:
http://www.nashbar.com/nashbar_photos/500/NA-FDCL-NCL-TOP.jpg
http://www.nashbar.com/profile.cfm?category=600083&subcategory=60001038&brand=&sku=2189&storetype=&estoreid=&pagename=Shop%20by%20Subcat%3A%20Component%20Accessories

You should be able to get that under the lower boss and the part that attaches to the FD is offset higher. (Edit: actually the picture might be upside down; then you'd put the band above the lower boss.)

Oh, that's a great link! Thanks jiveturkey!

BTW, your large chainring isn't installed correctly. That pin sticking out should be directly behind the crank. It keeps the chain from jamming between the chainring and the crankarm, should it jump off to the outside.

BTW, your large chainring isn't installed correctly. That pin sticking out should be directly behind the crank. It keeps the chain from jamming between the chainring and the crankarm, should it jump off to the outside.

Nice catch; both chainrings are in the wrong spot (the inner ring has that little bit of metal protruding toward the center). They're lined up together, but they both need to be shifted one bolt to the left--rotated counter-clockwise.

wow, thanks guys. I didn't even know what that pin was there for. I'll go and fix it. Thanks for the catch!

That looks totally fixable. I agree with the others that think lowering the FD will work. When the FD hits the large chainring, is it the inner plate that hits?...if so then the FD outer throw needs to be adjusted. The FD outer plate should clear the large chainring by several millimeters. It looks doable.

What shop allowed a bike to go out the door set up like that?

No, I transplanted the components from another frame onto this one. The funny thing is that the other frame is the replacement frame. Supposedly the two are the same measurements. But the water bottle bosses is different and the headtube length was different requiring a couple of more headset spacers. That one really threw me for a loop. I thought I put together the headset incorrectly and it took me like two days to figure it out.

To answer the other question, the outer FD plate hits the chainring if I try to clamp it directly underneath the water bottle boss. I don't think that can be adjusted out. It hits basically 1-2mm and there's no way to clear it without mounting the clamp directly onto the water bottle boss.

This is an easy fix, I've done it a hundred times. Can't quite see from the photos, but is the part where the FD bolts to the bracket slotted like in the one in JiveTurkey's post? All you have to do is bolt the bracket under the water-bottle boss, then unbolt the FD and slide it upwards slightly. If it's not slotted, it's pretty simple to use a circular file to elongate the hole upwards into a slot. You only need 1-2mm.

Or you can also file a circular bite-mark to wrap around the water-bottle boss:

http://i42.photobucket.com/albums/e346/DannoXYZ/Cycling/FDbracketAdjustment.jpg

I have the same problem on a bike that I just (almost) finished building up. In my case, however, my FD is not a braze-on, so I can't use Danno's suggestion. The bike is a hybrid-touring thing (Sora FD, Sugino 26-36-46 crank). Also, it isn't as close to fitting as Fredo's situation. Basically, the water bottle boss is smack dab in the middle of where I want to mount the FD. Mounting below is way too low, and mounting above is too high, though it almost works (moving from the middle to the big ring works about half the time. The other half it either won't go, or pops off to the crank side. ) Any suggestions?