IRD 10spd Elite wide range cassette with a compact double crank?

Hi guys,

I'm currently running FSA compact 50/34 cranks with Dura-Ace 7800 10spd drive train on my bike. I use 12/27 cassette in the back. I believe 12/27 is lowest you can go with a shimano short cage rear derailleur, but I still want to go lower on the cassette without going triple(an expensive conversion). So I thought about going with IRD(interloc racing design) Elite road wide range 10spd cassette, either 11/32 or 11/34. In order to do so, I believe I need a long cage rear derailleur. Would a long cage Dura-Ace rear derailleur(RD-7803) work with IRD's wide range 10spd cassette without any compatibility problems? The current XTR cassettes are 9spd only, so IRD seems to be the only way to go.

Any advice would be greatly appreciated. I need to save my knees from petellar tendonitis...

Aero-X

I can't find the specs for the 7803, but in general the Shimano road rear derailleurs only handle a rear cog up to 27 teeth. Even long cage (such as the current Ultegra long cage).

Even though you can usually go a tooth or two larger than spec (I run an 11-28 on my 105 long cage) 32 or 34 is probably too large, and would require a mountain RD, if you can get it to work (which you may be able to).

So, if you want to go with a 34 tooth large cog on your cassette, I would suggest trying it with a high end mountain RD capable of 34 teeth in place of your Dura-Ace... and don't forget to lengthen the chain.

EDIT: Even though mountain RDs are currently rated for only 9 speed... I think the amount of cable pull is the same as 10 speed, so you should actually be able to get it to work... You should ask the IRD people what derailleurs they suggest.

11-34, to have enough chain for big-big and no droop in small-small, probably need a MTB, 95mm, long cage rear derailleur. I don't think the 7803 will give you enough chain. The cage is not long and gets the extra chain with big pulleys only. See if you can find a 2006/7 XT or XTR..not the current ones w/o a barrell adjuster on the rear derailleur.

As others have noted, Shimano's ROAD rear derailleurs are not happy with cassette cogs bigger than 27t/28t rear cogs ...

BUT, several years ago, I discerned that the limitation is because of the 11t pulley wheel ... and, if you change the upper pulley wheel to a 10t, then the largest cog the derailleur can handle is often 32t (depending on the frame's rear derailleur hanger). On one frame, I was able to fit a 12-34 XTR cassette with a Shimano 6503 rear derailleur whose upper pulley wheel was swapped, but that was an exception (i.e., the frame had a long derailleur hanger).

As far as the short cage on the 7800 rear derailleur, I believe that any cage from almost any recent (post-1998) Shimano MTB (there are probably exceptions at the bottom of Shimano's lineup of MTB rear derailleurs) or Ultegra-or-105 pseudo-"touring" (e.g., 6503, 6603, 5503, 5603) rear derailleur can be substituted for the cage in your 7800 rear derailleur ... maybe, not. Maybe only the 6603 & 5603 cages can be subsituted ... OR, you can just buy a 6603 Ultegra rear derailleur (the pulley wheels are much BETTER than the ones on the 105 rear derailleur, yet the Ultegra rear derailleur only cost a few dollars more) because the cost of the cage (if you aren't cannibalizing a rear derailleur that you already have) + labor (if your shop does it) will probably be close to the price of an Ultegra rear derailleur.

OR, as Peter suggests, use a Shimano MTB rear derailleur ... but, As far as I know, you'll need to use the hubbub.com alternate anchor position to make the 9-speed Shimano rear derailleur act like a 10-speed Shimano rear derailleur.

If you can only find a new MTB RD without a barrel adjuster, you can use an in-line barrel adjuster that sits just inboard from your shifter. I'm using 9spd 105 shifter and the current XTR RD with an in-line adjuster, successfully. The barrel slips very slowly, and needs readjustment every few months.

__________________
"All that we see and seem is but a dream, within a dream..."

They were several IRC reviews a few months back. IRD cassette does not work well with shimano drivetrain....
Have you tried a SRAM 11/28 cassette?

Why not go 9 spd and use an MTB cassette? Few people have a burning need for an 11 t rear sprocket.

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"All that we see and seem is but a dream, within a dream..."

I think it will require a big re-do: cassette, shifter, RD...

Nope. 8/9/10s rear derailleurs(only exception being DA 8s) all have the same dimension and are cross compatible with different 'speed' shifters. a shimano MTB rear derailleur, even tho '9s' will shift 10s spacing fine and dandy w/o any modification or gizmo.

Or one of the jagwire barrel adjuster doohickeys that sick into the shifter or rear derailleur.

He's talking about replacing the cassette and RD in any case.

__________________
"All that we see and seem is but a dream, within a dream..."

Well, that isn't an accurate statement ...

The 8-/9-/10-speed Shimano rear derailleurs do not have the same dimensions.

FWIW. The length of the parallelogram of the 8-/9-speed XTR is 45mm (hinge pin to hinge pin). I measure the anchor point for the rear derailleur cable as being 20mm from the rear hinge.

Since my recollection is that the 8-speed 105 rear derailleur looks like the XTR's parallelogram, I would suppose that the 8-speed ROAD rear derailleurs also have 45mm parallelograms.

The 9-speed XTR rear derailleurs (e.g., 952) that I have are same as the 8-speed XTR rear derailleurs (950 & 951/[rapid rise]) except for the number of teeth on the pulley wheels + a cosmetic difference in the derailleur hanger bolt.

A 9-speed Ultegra 6503 rear derailleur's parallelogram is 43mm long, but the anchor point remains at 20mm from the rear hinge. Despite the difference in the length of the 9-speed ROAD parallelogram, the apparent reason that a Shimano MTB rear derailleur can be substituted for one of the 9-speed ROAD rear derailleurs is because the SLANT (the plane in the Z-axis) is at a steeper angle on the 9-speed rear ROAD derailleurs, thus both the 8- and 9-speed Shimano rear derailleurs apparenty have the same horizontal cage movement.

Now, the 10-speed Ultegra rear derailleur has an even shorter parallelogram (38mm) & steeper SLANT, but the anchor point is decidedly further from the rear hinge (22.5mm) -- approximately the same change in distance that using the hubbub.com anchoring would achieve when applied to an 8-/9-speed Shimano rear derailleur.

Now, while one might suppose that the combination of changes might account for continued interchangeability, I will note anecdotally that a 'quick' non-road test of a 10-speed Ultegra rear derailleur with its "normal" rear derailleur cable anchoring + 10-speed Campagnolo Ergo shifter yielded the same shifting rate as with either a 9-speed XTR or Ultegra rear derailleur with the hubbub.com anchoring + 10-speed Campagnolo shifter -- that may only be a fortunate coincidence for me since my preference is to use Shimano rear derailleurs/etc. (I love Shimano EXCEPT for their shifters) mated to Campagnolo shifters!

The 10-speed Shimano rear derailleurs retain the double-bladed "molly" hook/(washer) that was originally introduced with the "regular" 8-speed Shimano rear derailleurs to allow them to be used with the original, 8-speed DA shifters (i.e., Shimano's ALTERNATE ANCHOR POSITION @ 9 o'clock).

To achieve BACKWARD compatibility when using a 10-speed Shimano rear derailleur with a 9-speed cassette & shifter you would more-than-likely use the ALTERNATE REAR DERAILLEUR CABLE ANCHORING POSITION (I don't remember the documentation indicating this, BTW, and I don't have a sheet handy), hence the legacy molly "washer."

I can neither refute nor confirm this statement through direct application ... but, I would be inclined to believe it is incorrect based on my successful substitution of a 10-speed Shimano rear derailleur for a 9-speed rear derailleur which was hubbub'd -- that suggests to me that a 9-speed Shimano MTB rear derailleur may NOT be directly interchangeable "w/o any modification or gizmo" (e.g., shiftmate) when used with a 10-speed Shimano shifter & cassette.

So, while I was grateful that Shimano's 8-/9-speed MTB & ROAD shifters & rear derailluers are indeed interchangeable despite what Shimano's marketing and/or tech people apparently indicated back at the turn of the Century, when my wife told me that the 12-27 cog wasn't giving her a low enough gear -- since I had a 12-32 & XTR rear derailleur -- it was only a question of a few minutes of parts swapping to determine that Shimano's folk were inaccurate with regard to the mandate to only use components from a given group in a given drivetrain (i.e., only 105 with 105, Ultegra with Ultegra, DA with DA, XTR with XTR, etc.), otherwise who knows if-or-when I would have crossed the threshold of investigating possible component compatibility.

While I think my experience is reproduceable, if someone wants to adhere to whatever-or-whichever "conventional wisdom" they are familiar with with regard to the rear derailleurs & shifters, then that is their prerogative.

But, if anyone ends up with unsatisfactory results when trying to use their 8-/9-speed Shimano rear derailleur with a 10-speed Shimano drivetrain, or vice-versa, then I think it is worth trying the alternate anchoring positions.

Not sure what you just said in your 'epic' upstairs BUT. I have installed many otherwise '9s' rear derailleurs onto shimano 10s drivetrains as well as using a '10s' rear derailleur as a replacement rear derailleur on many 8s and 9s 'systems. The ONLY rear derailleur requiring the mysterious alternative cable placement was when using a DA 8S rear derailleur in order to use the 'new' at the time 9s STI. OR when using DA 8s STI and needing a new rear derailleur after DA 8s were out of production. All that stuff from more than a decade ago(9s shimano introduced in the 1997 model year).

So the parallelograms aren't identical..all are cross compatible, road to MTB, 8s, 9s, 10s. except for DA 8s and perhaps DA 7900.

What is the hubbub alternate anchor point?

http://www.hubbub.com/articles_ergopower.html