Bicycle Mechanics - Franken Derailleur -- 105 (5500) vs. Ultegra (6500)

So earlier in the week I startedthis thread about whether I could swap a short cgae from a busted Ultegra derailleur onto what had been a long cage 105

http://www.bikeforums.net/showthread.php/795329-Franken-Derailleur-would-this-work

Well the swap is going to work just fine and was actually really easy to do. But the process of tearing down both dearilleurs revealed some differences between the two that help explain cost, weight and quality differences between 105 and ultegra (which I always wondered about since I ride both and never really noticed appreciable performance difference).

1. Ultegra uses lighter pivot bolt. The ultegra bolt is hollowed out while the 105 bolt is solid.

2. Ultegra uses better seals to keep dirt out: There are rubber o-rings around the head and middle of the ultegra bolt. 105 bolt has a plastic collar around the head an no o-ring in the middle (although there is a groove where an o-ring could be added).

3. Ultegra uses better springs. All springs in the Ultegra derailleur are heavier duty than those on the 105.

4. Jockey wheels on Ultegra are higher quality -- they just feel more substantial and roll more smoothly.

So there you have it, just some observations from tearing down rear derailleurs to their nuts and bolts. All parts seem interchangeable so once I rebuild, I will have a Shimano 10tegra 6000 (6500+5500/2) rear derailleur.

Love it. I think it is our right as mad cyclists to brew up new combinations of common components :0) I have recently made a FrankenSRAM RD using an Apex long cage and Force main body. I wanted Force good looks but with a wider range of ratios. This Force + Apex combination works OK in practice.

I tried the reverse combination out of interest but the Force cage won't fit the Apex body, the spindles are different lengths. Jockey wheels are identical but bearing spacers and cage bolts are different diameters.

Needed to use the Apex spring to get the cage tension right. Assembly/disassembly very straightforward.

Anyone else brewing their own?

Haven't had an excuse to make a franken derailleur, but may need to find one. Thanks for the enlightenment.

As someone who commented on the initial post regarding the franken deralleur I gotta say this follow up is great, love the breakdown of the differences between the 105 and ultegra. Now we just need to have a final thread or update about how it works when its on a bike and then a comparison of that experience to what the original 105 and ultegra derailleurs worked.

I'm going to swap out the derailleur on my commuter today so will report back next week after a week of commuting.

Ok, maybe that's a bit dramatic. But I rode my newly installed rear dearilleur cobbled from 105 body and ultegra bits. It worked flawlessly.

I used the 105 pivot bolt, despite Ultegra one being lighter and having better seals, because the head of Ultegra one didn't seem to seat quite right in the 105 body (I think it would have worked, however). I did put an o-ring on the bolt shaft (105 bolt grooved for o-ring but doesn't come with o-ring) so it should provide some added benefit there. I used Ultegra springs, cage, and jockey wheels all of which seemed a bit higher quality that what comes with 105.

-- Did newly installed derailleur shift better than the 105 one I had been riding? Yes

-- Did the adding of Ultegra bits result in this increased performance over a regular 105 derailleur? Probably not.

While the jockey wheels and springs from Ultegra are higher quality, I doubt quality difference would have allowed me to notice any performance difference (I don't really notice difference between 105 and Ultegra generally). Improved shifting almost certainly is attributable to fact that the ultegra jockey wheels I used aren't as worn as those on the 105 and, most importantly, the act of rebuilding and installing the derailleur means basically I tuned up drivetrain. In other words, had I taken the 105 derailleur off, cleaned, greased and lubed everything, then installed with freshly adjusted cable, I likely would have noticed similar improvement in performance.

-- So what did we learn: If you're are riding a triple and would prefer a double (or vice versa) but don't have a functioning derailleur or don't want to buyone, you can swap the cage (at least for the 9 speed shimano components up to Ultegra).

-- It is certainly worthwhile to occasionally break shimano derailleurs down for a complete overhaul. The springs for both the cage and pivot bolts do get dirty and the pivot bolt can get encrusted with gunk (dried out grease, road grime that gets past seals, etc.), which results in degraded performance. Before this project, I had not thought to do that, but I will in future. As with most things, Park tool shows you how...
http://www.parktool.com/blog/repair-help/rear-derailleur-overhaul

Hey there DOS, thanks for a very informative series of posts :O)

Hey there DOS, thanks for a very informative series of posts :O)

+1

Interesting to see 1) that there is a reason for the cost difference and 2) the details of those differences observed by a neutral party.

Thank you. :thumb: