Bicycle Mechanics - rear derailleur not shifting largest cog

I posted recently for some info regarding spacers to install a 7-speed freewheel on a campy hub a friend gave me. It's all going onto my '83 Miyata 1000. The 7-speed freewheel turned out to be a cassette I need to return to Nashbar. In the meantime, I stopped at an LBS where they threw on a cheap 6-speed freewheel with no spacers (I believe). It's a really tight squeeze mounting the wheel, I'm guessing it's because the hub is 126mm and my spacing is 120mm.

While installing the new wheel, I also cleaned up and installed a Suntour V-GT Luxe long cage rear derailleur. I can't shift into the largest cog, and can just barely squeeze into the second. The limit stop isn't interfering, and the cable seems stretched properly. I can tell that the derailleur simply doesn't move any further. It certainly should reach all the gears, I believe. So, I'm guessing something is up with the hub and the freewheel. I'm very hazy on the spacing, or no spacing, needed.

Here's pics:
http://i24.photobucket.com/albums/c10/d3pl3t3d/Miyata/IMG_2220.jpg
http://i24.photobucket.com/albums/c10/d3pl3t3d/Miyata/IMG_2221.jpg
http://i24.photobucket.com/albums/c10/d3pl3t3d/Miyata/IMG_2222.jpg

Hopefully, with some experience, the pictures show something about the setup that's wrong.

thanks,
-Michael

I finally pulled the derailleur and put another on. It’s also a long cage derailleur, Shimano. Same issue. Can’t reach the large cog, stops right at the second to last. Definitely not the L-limit screw, and I tried adjusting the B-Screw on the Suntour but it didn't help.

I’m convinced I’ve missed something about the new hub and freewheel. Both are new additions. I didn't install the freewheel an LBS did, but I'm about to remove it. Frankly, I've never messed with these parts before. So, I'm totally lost and brushing up quickly with Zinn's guide.

I can tell I’m stretching to 126mm from 120mm when I struggle to get the wheel on, but I’ve heard that’s fine or expected. Is it that the hanger and derailleur is now pushed that much further away, thus not allowing the pulleys to reach back as far?

-Michael

With the hub dismantled and the freewheel off, here's some pics...

http://i24.photobucket.com/albums/c10/d3pl3t3d/Miyata/axle.jpg
http://i24.photobucket.com/albums/c10/d3pl3t3d/Miyata/spacers.jpg

Here�s some history that might say something: I�d taken the hub/wheel to an LBS and asked for a 7-speed freewheel installed. He kept it overnight to mess with spacing and dish the wheel, and installed a Shimano MegaRange. But I found that there were 2 broken teeth and two cracked, so I took it back, had him remove the freewheel and give me my money back. I�m guessing whatever spacing he put on, stayed on. (after visiting 4 shops for a variety of reasons I'm starting to find that my LBS's stand for Lotsa-Bull-S**t)

Between the cone and locknut on the drive-side:
7mm
4mm
5mm (weird pulley shape)
= 16mm of spacers? I just think that's wrong and is why I'm struggling to get the axle into the drops, and then the derailleur is too far away to reach back to the large cog. Maybe?

Chain is to short, see other thread.

It's not too long, but it is probably too short.

It may also help to rotate the derailleur slightly clockwise, using the limit screw above the two regular travel-limit screws.

You have way too many spacers on the right side of the hub-axle. Move one or two of them to the left side so that the top-cog (14t) is about 4mm away from the inner-face of the drop-out. There should be just 0.5mm of clearance between the outer-plate of the chain and the dropout when you're in the tallest gear. This will laterally shift the largest cog to the right by 5mm or so and place it right where the derailleur currently stops moving.

BTW - If this picture was taken with the chain on the small chainring in front, then the chain is definitely too short:

http://i24.photobucket.com/albums/c10/d3pl3t3d/Miyata/IMG_2221.jpg

BTW - If this picture was taken with the chain on the small chainring in front, then the chain is definitely too short:

Even if it was taken with the chain on the big ring, That chain is still to short.

Thanks everyone,

Danno, the spacing is exactly the problem I suspected and just needed help confirming. And the chain was definitely too short, I lengthened it earlier in the posts. The derailleur should be straight down, and not extended past the derailleur body, yes?

Additionally, that axle measured 146mm, spaced (incorrectly for my needs) toward 130mm drops. I decided I didn't need that, so, I grabbed an old axle that's 135mm and I'm working on spacing that with the Campy hub.

Now that I'm not struggling with that 146mm axle, what formula should I follow for the spacing on this 135 in my 126 drops?

"Move one or two of them to the left side so that the top-cog (14t) is about 4mm away from the inner-face of the drop-out. There should be just 0.5mm of clearance between the outer-plate of the chain and the dropout when you're in the tallest gear. This will laterally shift the largest cog to the right by 5mm or so and place it right where the derailleur currently stops moving. "

What part of the above still applies?

thanks again, I'm almost there.... next up, dishing (grin)
-Michael

Now that I'm not struggling with that 146mm axle, what formula should I follow for the spacing on this 135 in my 126 drops?

"Move one or two of them to the left side so that the top-cog (14t) is about 4mm away from the inner-face of the drop-out. There should be just 0.5mm of clearance between the outer-plate of the chain and the dropout when you're in the tallest gear. This will laterally shift the largest cog to the right by 5mm or so and place it right where the derailleur currently stops moving. "

What part of the above still applies?

thanks again, I'm almost there.... next up, dishing (grin)
-MichaelYes, you always want the cogs as close to the dropout as possible. First to reduce dish as much as possible. And it aligns the 1st cog in a standard position for the RD. If you have multiple wheels with index-shifting, you want them all spaced the same way from the dropout so that when you swap wheels, no adjustment of the RD is needed.

I recommend you stay with the 130mm spacing, makes for a stronger wheel with less dish. Not that difficult to squeeze a 130mm wheel into 126mm dropouts anyway.

I recommend you stay with the 130mm spacing, makes for a stronger wheel with less dish. Not that difficult to squeeze a 130mm wheel into 126mm dropouts anyway.

How does a 130mm spacing on a Campagnolo freewheel hub make a stronger wheel with less dish than the properly spaced 126mm hub?

Respace the hub back to the original 126mm. It allows you to use 6s and 7s freewheels and places less stress on the axle than a comparably spaced 130mm hub.

OP, If you need it I will post the axle spacing for a 126. I don't remember them off the top but i can check when I get home.