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Discussion Starter · #1 ·
Drivetrain SetUp
Shimano 105 Shifter (Tripple)
105 FD (Tripple)
105 RD (Long Cage)
Dura Ace 12-23 Cassette
SRAM PC98 Chain
FSA Corbon Pro Elite Compact (50-34)


I've just swap out my tripper crank for FSA Compact crank on my 105 Groupset, and i have problem with the gear. I am unable to use all the 18 gears that i got on the gearset.

When ever i'm i'm using 34 chainring, i wont be able to shift to 12th, 13th and 14th cassette without the chain rubbing on my 50 chainring. Not on the FD but the chainring.

I wonder is it because of the chain lenght? The Long Cage RD? Or any other problem?

I checked with a friend of mine who is using Campag Compact Crank and the Compact FD, he have no problem to use all the 20 gears that he has.

So i wonder is there anyone had the same problem like this before? Or is there anyone know how to solved this?

Your contribution/help will be much appreciated, thanks
 

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Just Ride!!!!!
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Did you get the right size BB (108mm)? Also, I believe you need a double specific component especially coming from a tripple component may not be compatible.
 

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NeoRetroGrouch
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fea said:
Drivetrain SetUp
Shimano 105 Shifter (Tripple)
105 FD (Tripple)
105 RD (Long Cage)
Dura Ace 12-23 Cassette
SRAM PC98 Chain
FSA Corbon Pro Elite Compact (50-34)


I've just swap out my tripper crank for FSA Compact crank on my 105 Groupset, and i have problem with the gear. I am unable to use all the 18 gears that i got on the gearset.

When ever i'm i'm using 34 chainring, i wont be able to shift to 12th, 13th and 14th cassette without the chain rubbing on my 50 chainring. Not on the FD but the chainring.

I wonder is it because of the chain lenght? The Long Cage RD? Or any other problem?

I checked with a friend of mine who is using Campag Compact Crank and the Compact FD, he have no problem to use all the 20 gears that he has.

So i wonder is there anyone had the same problem like this before? Or is there anyone know how to solved this?

Your contribution/help will be much appreciated, thanks
If you are using the triple octalink bottom bracket, I would think that the spindle would be too long and would be LESS prone to rubbing. As the other poster said, be sure you have the correct length BB.

The triple front derailleur may not shift the front well, but I don't see how it would cause this problem.

The long cage rear derailluer should be no problem.

The chain length shouldn't matter unless it actually goes slack when in the 34/14, etc. Since you had a 30 on the triple, it should be OK.

I'm not familiar with SRAM chains - that's not an 8-speed chain, is it? That would be wider and may contribute to the rubbing.

All I can think of.

TF
 

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Discussion Starter · #4 ·
Thanks for your reply

I am using the FSA ISIS BB that came togather with the Compact Crank, not so sure about the size though.

The SRAm Chain i used is the 'Latest' on 8/9 speed (PC-89).

Hmmm.... may be like y guy said, is the BB, cause i dun think the tripple FD cause this, even thou i know that the FD doesnt allow me to do a 'single action shifting', i always have to shift down and click up in order to get to 34th teeth without the chain rub on the FD, but it still doesnt cause the chain rub on the 50th Chainring.

I'll go check the BB size again.
 

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It depends not only on the parts used, but also the frame. If you have short chainstays the chain is forced into a tighter angle in the 12, 13 & 14T sprockets. That said, you shouldn't be using these with the 34 chainring anyway as it increases the wear on the drivetrain.

Check the chainline. If the chain is on the middle sprocket of the cassette, the chainline should run between the chainrings. If it appears to be more lined up on the outer ring then that will be the problem, and a thin spacer behind the driveside cup of the bottombracket should cure it. If you have a external bottom bracket set up I'm not sure if this will work.
 

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some suggestions...

BB spindle length has already been mentioned. It would have to be shorter than it should be to cause this problem and generally there are no shorter spindles than those appropriate for octalink or ISIS doubles.

It never hurts to check the chainline. The tip of a tooth big ring should be 47-48mm from the center of the seat tube. Measure from the side of the ST and add 1/2 the ST diameter to get this dimension.

Short chainstays can contribute to this problem. Not many bikes have realy short chainstays these days, but stays under 40cm could be problem.

The other thing not mentioned is that the 34/12 should never be used anyway, due to the extreme chainline. It would not be unusual to have rub a little rub in the 34/13. The 34/14 should never rub. I can use the 28/14 on my triple.
 

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It's a common problem.

I use a 2mm spacer to move my bottom bracket that far to the right. It helps, but I still get enough chain rub in the second smallest cog to remind me that I need to shift chainrings. My smallest cog is unuseable with the small chainring. I haven't tried it but using a wider spacer would probably cause problems with my left crankarm.

If your crank happens to be an octolink, a more elegant (though more expensive) solution might be to use an XTR bottom bracket to respace your chainline.
 

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Steaming piles of opinion
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One possibility - the FSA Carbon Pro Elite was possibly designed for 10sp drivetrains - there's a few different models, and some shops aren't great at differentiating them. I don't know if there's a specific model for less than 10sp drivetrains, but there are for campy vs shimano.

Point is, the rings may be slightly too close together for your specific setup. You might be able to find some wider spacers to move the 34 inwards a bit to create the clearance needed.

But really, it's not much of an issue. Like a previous poster said, you probably shouldn't be using the extreme gear combinations anyway. You're not losing anything by not crossing the drivetrain - the gearing overlaps on the two chainrings, and choosing a similar gear that is less crossed is more efficient and less wearing on the chain and cogs. The gear chart below shows the relative gear-inches of each combination. A 34x13 is essentially the same gear as a 50x19, so you're not missing a thing other than the chance to send your cogset to an early grave.


.........34..... 50
23......38.7......56.9
21......42.4......62.3
19......46.8......68.9
18......49.4......72.7
17......52.3......77.0
16......55.6......81.8
15......59.3......87.2
14......63.6......93.5
13......68.4......100.7
12......74.1......109.0
 

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eminence grease
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Spoke Wrench said:
It's a common problem.

I use a 2mm spacer to move my bottom bracket that far to the right. It helps, but I still get enough chain rub in the second smallest cog to remind me that I need to shift chainrings. My smallest cog is unuseable with the small chainring. I haven't tried it but using a wider spacer would probably cause problems with my left crankarm.

If your crank happens to be an octolink, a more elegant (though more expensive) solution might be to use an XTR bottom bracket to respace your chainline.
Second that. FSA Compact on my Orbea (with 407 stays) rubbed in the smallest 3 gears. Of course, it's only the 2nd and 3rd that matter as you shouldn't be using the 1st. But, the loss of those two made it darn near unusable for anything but climbing in the smaller ring.

Two things will improve it. One, a 2mm spacer as mentioned and two, a 48T big ring. The latter is a shade smaller and thinner than the 50T and it alone got the #3 cog back for me. To get 2 and 3 back though, the spacer was needed.
 

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n00bsauce
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I like the thought of increasing the spacing between the inner and outer chain ring, especially since the OP has a triple FD/brifter. Does anyone make the necessary spacers and bolts to accomplish this?
 

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Mel Erickson said:
I like the thought of increasing the spacing between the inner and outer chain ring, especially since the OP has a triple FD/brifter. Does anyone make the necessary spacers and bolts to accomplish this?
In many sizes:

http://aebike.com/page.cfm?PageID=30&action=list&Category=202&Brand=462&type=T

Any LBS should have them or be able to order.

Existing bolts should work, longer ones are available if needed. Might also check the old triple to see if there are any parts to be scavenged to the cause.
 

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on a similar note for you gear heds

I was wondering - what is the mph difference between a 53T ring and a 52T ring and a 50T ring?

Now - what if you used an 11-23 vs 12-23 ?

what cadence would you have to use to reach equal speed in each combination?

which is more efficient?
 

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Do you have a calculator?

littlelamb said:
I was wondering - what is the mph difference between a 53T ring and a 52T ring and a 50T ring?

Now - what if you used an 11-23 vs 12-23 ?

what cadence would you have to use to reach equal speed in each combination?

which is more efficient?
It's all about ratios. If the ratio of front/rear is the same, then it is the same gear. For example, a 53/18 is about the same as a 39/13. A 50/12 is about the same as a 53/13. At the same cadence, then the same front/rear ratio gives the same speed. Alternatively, if a gear is 10% higher (larger ratio) then the cadence is 10% lower to go the same speed. If you're putting out the same power at the same cadence, then it doesn't make any efficiency difference whether you're using a 53/19 or 50/18. Using the big ring is typically more efficient (by a small amount) than achieving the same gear using the small chain ring.
 

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Discussion Starter · #15 ·
Problem solved - kind of

Finally i manage to get rid of the Chainring rubbing on my 50t while using the 13t,14t cassette.

The solution was to add wasser at the 34t chainring, to create some space in between 34t and 50t.

I took the suggestion from u guys and ask my LSB to add wasser, unfortunately, he was unable to find any tiny (spare)wasser in the shop, when i was about to purchase the Titatnuim DuraAce chainring nut - with wasser that i know of, he was kind enough to dismentle an older cranksset to give me the wasser that we are looking for. (Good thing, i dun have to spend extra money to buy the Titanium Nut; not so good thing, it was my excuse to buy the Titanium Nut. =P ).

Well, as i mentioned, problem kind of solved - i managed to use my 13t and 14t, there is still rubbing going on my 12t, but as someone said b4 and we all kind of know - we dont use the 34t on 12t cassete. so i thinks its ok even thou it make noice when i accidently use it.

Again, thanks for yours help.
 

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Just Ride!!!!!
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I just dont understand how the chain would be rubbing on the big chainring when you're on the smallest cassette. If anything it should be rubbing on the FD cage. Then again, you are using a tripple FD so maybe it has a wider cage? I would save some money and get a new FD and double shifter. I'm surprised you're even using those gear combination, the lowest cassette combination I've used with my 34T was 17t gear, then I would shift to the 50t if I wanna go any faster. Just my opinion. :)
 

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Discussion Starter · #17 ·
Why spend Money while its free

Why would one spend extra money to change FD and shifter while those arent even the cause of the problem - especially when a few free wasser can solve the problem.

No offense. Assuming you are running a 9 speed double - arent you suppose to be able to use all 18 gears (yes - i agreed that premature wear out on your drivetrain if you do so).

If 17t is the smallest cog u will ever use while running on 34t chainring, you only going to run 13 gears on your bike - assumming you are using a 12t-23t cassette.

Is this suppose to be the way on how to ride and maintain your drivetrain's lifespan at the same time?

Somehow none of the route/path that i rode were design/meant for immediate Cadence change from 90 rpm to 130 rpm in a just one gear shift. So i think i'll take my chance to use my 13t and 14t while riding. =)
 

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fea said:
No offense. Assuming you are running a 9 speed double - arent you suppose to be able to use all 18 gears (yes - i agreed that premature wear out on your drivetrain if you do so).
No. I can remember it being advised against when I was running 7 speed in the 80's. It is inefficient as well as higher wear on the chain etc. The reason compacts are more susceptible to rub is the differenc in chainring size.
 

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Just Ride!!!!!
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No offense taken. Technically, yes you suppose to be able to use all 18~20 gears on a double, I just never seen anybody use 12,13,14 with the small chainring. But if that is your riding style, that is perfectly fine. :)
 

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eminence grease
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mecam said:
No offense taken. Technically, yes you suppose to be able to use all 18~20 gears on a double, I just never seen anybody use 12,13,14 with the small chainring. But if that is your riding style, that is perfectly fine. :)
I think there are tons of people who ride 99% of the time in their small ring. I ride almost all the time in 39x13-14-15. It's called spinning.

It's also written in just about every book I've ever read that you never use 39xLittlest or 53xBiggest due to cross-chaining. And that logic extends to compacts. Ask just about anyone on this board and any other board and you'll get the same answer. It's just one of those things people know. But yes, technically a double should shift all those gears.

There is nothing unusual about the chain rubbing on the inside of the big ring in regular or compact set-ups. I have bikes that lose the two smallest cogs with a traditional 53x39 crank. Sometimes taking the big ring to 50 fixes it, sometimes you need a spacer, and sometimes it doesn't matter.

The problem sometimes comes with the change to a compact where you lose the 2nd and 3rd cog as well as the 1st. That's what happened on my bike and it took some creative work to bring the two back into play. It has nothing to do with the FD or the shifters or anything else, it's simply the geometry of the bike. A spacer will fix it and a 48T big ring helps too.
 
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