MTB front derailleur on road bike problem- NOT indexing issue

[Dan Daniel]

I changed my chainrings to 46/36/26 and tried installing an XT front
derailleur, thinking that its profile would match the chainrings
better and give me better shifting.

I am using barend shifters so indexing is not an issue.

Both the XT and the existing derailleur are bottom pull, bottom swing.

But the cable attachment point is further to the inside on the XT than
on the old road derailleur (RSX or RS100, can't remember and the label
is gone).

So when I go to shift, the end of the cable attachment arm hits the
fender. I can't move the fender back any- it's already too tight to
remove the wheel without deflating it. This is a bike with 42 cm
chainstays.

On another bike with much tighter geometry, I ran into the same basic
problem. I was able to use it because that bike has no fenders, but
the cable arm is very close to the rear tire. I doubt I could use a
larger tire- 23mm right now.

Is this typical for all MTB derailleurs? Or is it specific to bottom
pull, bottom swing designs? Would a bottom pull top swing avoid this
problem? Or some model other than XT? Any experience mounting MTB
models on road bikes much appreciated.

 

[Mark Hickey]

Dan Daniel <[email protected]> wrote:

>I changed my chainrings to 46/36/26 and tried installing an XT front
>derailleur, thinking that its profile would match the chainrings
>better and give me better shifting.
>
>I am using barend shifters so indexing is not an issue.
>
>Both the XT and the existing derailleur are bottom pull, bottom swing.
>
>But the cable attachment point is further to the inside on the XT than
>on the old road derailleur (RSX or RS100, can't remember and the label
>is gone).
>
>So when I go to shift, the end of the cable attachment arm hits the
>fender. I can't move the fender back any- it's already too tight to
>remove the wheel without deflating it. This is a bike with 42 cm
>chainstays.
>
>On another bike with much tighter geometry, I ran into the same basic
>problem. I was able to use it because that bike has no fenders, but
>the cable arm is very close to the rear tire. I doubt I could use a
>larger tire- 23mm right now.
>
>Is this typical for all MTB derailleurs? Or is it specific to bottom
>pull, bottom swing designs? Would a bottom pull top swing avoid this
>problem? Or some model other than XT? Any experience mounting MTB
>models on road bikes much appreciated.

You should get a "traditional" top swing front derailleur. As a
bonus, you can get an LX designed for 48 tooth rings (or an XTR for
46, or an XT for 44). All but the XTR are relatively cheap too.
It'll probably have to be special ordered though.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

 

[Dan Daniel]

On Mon, 28 Jun 2004 22:04:26 -0700, Mark Hickey <[email protected]>
wrote:

>Dan Daniel <[email protected]> wrote:
>
>>I changed my chainrings to 46/36/26 and tried installing an XT front
>>derailleur, thinking that its profile would match the chainrings
>>better and give me better shifting.
>>
>>I am using barend shifters so indexing is not an issue.
>>
>>Both the XT and the existing derailleur are bottom pull, bottom swing.
>>
>>But the cable attachment point is further to the inside on the XT than
>>on the old road derailleur (RSX or RS100, can't remember and the label
>>is gone).
>>
>>So when I go to shift, the end of the cable attachment arm hits the
>>fender. I can't move the fender back any- it's already too tight to
>>remove the wheel without deflating it. This is a bike with 42 cm
>>chainstays.
>>
>>On another bike with much tighter geometry, I ran into the same basic
>>problem. I was able to use it because that bike has no fenders, but
>>the cable arm is very close to the rear tire. I doubt I could use a
>>larger tire- 23mm right now.
>>
>>Is this typical for all MTB derailleurs? Or is it specific to bottom
>>pull, bottom swing designs? Would a bottom pull top swing avoid this
>>problem? Or some model other than XT? Any experience mounting MTB
>>models on road bikes much appreciated.
>
>You should get a "traditional" top swing front derailleur. As a
>bonus, you can get an LX designed for 48 tooth rings (or an XTR for
>46, or an XT for 44). All but the XTR are relatively cheap too.
>It'll probably have to be special ordered though.
>
>Mark Hickey
>Habanero Cycles
>http://www.habcycles.com
>Home of the $695 ti frame


Oh sh*t.... I meant top swing all along maybe? Meaning that the clamp
band is above the pivot arms, yes? Traditional as in what every road
derailleur I have ever seen looks like (although now I see
bottom[clamp below or on level with pivots] swing front derailleurs
some places). Well, this is what I see called a top swing-
http://cambriabike.com/shift&der/shimano_deore_xt_m760_front_derailleur.htm

That is NOT what I have.


THIS is the style I have-
http://cambriabike.com/shift&der/shimano_lx_m571_front_derailleur.htm

although the XT version of it. Where the cable clamps, that point is
maybe 5mm further to the center of the bike on the XT than on the
RSX/RX100 and two 105s that I have. It is this displacement of the
cable anchor point that causes the arm to hit the fender when I shift
up.

Since you and I might be backward in our names here, do you mean that
I should get a front derailleur like the XT 760 shown above- clamp
below or in line with the cage? That this style will be less likely to
interfere as it travels inward?

(And do you really see that style as the traditional? From your web
site, I must admit that I see you as old enough to remember a day when
that ******* MTB low-down clamp thing didn't exist

 

[Chris]

"Dan Daniel" <[email protected]> wrote in message
news:[email protected]...
> On Mon, 28 Jun 2004 22:04:26 -0700, Mark Hickey <[email protected]>
> wrote:
>
> >Dan Daniel <[email protected]> wrote:
> >
> >>I changed my chainrings to 46/36/26 and tried installing an XT front
> >>derailleur, thinking that its profile would match the chainrings
> >>better and give me better shifting.
> >>
> >>I am using barend shifters so indexing is not an issue.
> >>
> >>Both the XT and the existing derailleur are bottom pull, bottom swing.
> >>
> >>But the cable attachment point is further to the inside on the XT than
> >>on the old road derailleur (RSX or RS100, can't remember and the label
> >>is gone).
> >>
> >>So when I go to shift, the end of the cable attachment arm hits the
> >>fender. I can't move the fender back any- it's already too tight to
> >>remove the wheel without deflating it. This is a bike with 42 cm
> >>chainstays.
>
>
>
> Oh sh*t.... I meant top swing all along maybe? Meaning that the clamp
> band is above the pivot arms, yes? Traditional as in what every road
> derailleur I have ever seen looks like (although now I see
> bottom[clamp below or on level with pivots] swing front derailleurs
> some places). Well, this is what I see called a top swing-
>
http://cambriabike.com/shift&der/shimano_deore_xt_m760_front_derailleur.htm
>
> That is NOT what I have.

>
> Since you and I might be backward in our names here, do you mean that
> I should get a front derailleur like the XT 760 shown above- clamp
> below or in line with the cage? That this style will be less likely to
> interfere as it travels inward?
>

I'm nowhere near the expert Mr. Habanero is, but if this were my bike, I'd
do one of two things:
-cut the fender out where the derailleur is gunking things up. If the
problem is that far down the frame it's not going to get your bike or your
self much dirtier to lose that bit of fender.
-try out a bottom-swing front derailleur.

I know this smacks of "take it to marketplace," but I have an XTR BP/BS 1
1/8 if you want to try it. It has been mounted and setup was attempted - so
there have been a few workstand shifts - then I realized I was a moron
trying to get 105 shifters to work it correctly. So, it's essentially new.
I'll send it to you for $20. Here's a pic:
http://cambriabike.com/SALE/derailleurfrt/shimano_xtr_m-952_front_derailleur
..htm

Chris

 

[Mark Hickey]

Dan Daniel <[email protected]> wrote:

>Oh sh*t.... I meant top swing all along maybe? Meaning that the clamp
>band is above the pivot arms, yes? Traditional as in what every road
>derailleur I have ever seen looks like (although now I see
>bottom[clamp below or on level with pivots] swing front derailleurs
>some places). Well, this is what I see called a top swing-
>http://cambriabike.com/shift&der/shimano_deore_xt_m760_front_derailleur.htm
>
>That is NOT what I have.
>
>
>THIS is the style I have-
>http://cambriabike.com/shift&der/shimano_lx_m571_front_derailleur.htm
>
>although the XT version of it. Where the cable clamps, that point is
>maybe 5mm further to the center of the bike on the XT than on the
>RSX/RX100 and two 105s that I have. It is this displacement of the
>cable anchor point that causes the arm to hit the fender when I shift
>up.
>
>Since you and I might be backward in our names here, do you mean that
>I should get a front derailleur like the XT 760 shown above- clamp
>below or in line with the cage? That this style will be less likely to
>interfere as it travels inward?
>
>(And do you really see that style as the traditional? From your web
>site, I must admit that I see you as old enough to remember a day when
>that ******* MTB low-down clamp thing didn't exist

You've probably already got as good a FD as you're going to get for
your dilemma... you have a 'traditional top swing' FD. Probably time
to trim the fender.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame

 

[Dan Daniel]

On Tue, 29 Jun 2004 05:26:18 -0400, "Chris"
<[email protected]> wrote:

>
>>
>
>I'm nowhere near the expert Mr. Habanero is, but if this were my bike, I'd
>do one of two things:
>-cut the fender out where the derailleur is gunking things up. If the
>problem is that far down the frame it's not going to get your bike or your
>self much dirtier to lose that bit of fender.

I've thought of this. Don't like it, but it might be the answer... IF
the arm will clear the tire. Once it hit the fender I stopped
checking.

>-try out a bottom-swing front derailleur.
>

I'll borrow an old one from a friend and see what happens.

The terms are getting to me The XTR-952 you have is called 'top
swing' on the Cambria web site and the Shimano site-

http://bike.shimano.com/mtb/XTR/componenttemplate.asp?partnumber=FD-M952

>I know this smacks of "take it to marketplace," but I have an XTR BP/BS 1
>1/8 if you want to try it. It has been mounted and setup was attempted - so
>there have been a few workstand shifts - then I realized I was a moron
>trying to get 105 shifters to work it correctly. So, it's essentially new.
>I'll send it to you for $20. Here's a pic:
>http://cambriabike.com/SALE/derailleurfrt/shimano_xtr_m-952_front_derailleur
>.htm
>
>Chris
>

Hmmm... very tempting. Thanks for the offer. Let me do some more
experiments and I might take it off your hands.

 

[James Thomson]

"Mark Hickey" <[email protected]> wrote:

> You've probably already got as good a FD as you're going to
> get for your dilemma... you have a 'traditional top swing' FD.

You're getting your terms confused, and it probably doesn't help that the
Cambria Bike page showing the conventional LX derailleur also mistakenly
describes it as 'top swing'.

A 'top swing' derailleur clamps to the frame below the parallelogram. A
traditional, 'normal swing' or 'bottom swing' clamps to the frame above the
parallelogram, and that's what Dan has. 'Traditional top swing' is a
contradiction.

A top swing derailleur is less likely to foul the mudguard than the one Dan
is using currently.

James Thomson

 

[James Thomson]

"Dan Daniel" <[email protected]> wrote:

> Is this typical for all MTB derailleurs? Or is it specific to bottom
> pull, bottom swing designs?

MTB derailleurs have a longer arm (and hence require more cable pull) than
road ones, so conventional (bottom swing) MTB derailleurs like yours are
more likely to foul a mudguard.

It's generally not a problem for 'top swing' or top-pull derailleurs,
because they have the lever arm in a different place.

> Would a bottom pull top swing avoid this problem?

Yes, almost certainly. I used a bottom-pull, top-swing XTR 950 model to get
around this problem on my touring bike. The cable pulls the clamp down and
to the right, away from the mudguard.

James Thomson

 

[Dan Daniel]

On Tue, 29 Jun 2004 18:46:35 +0200, "James Thomson"
<[email protected]> wrote:

>"Dan Daniel" <[email protected]> wrote:
>
>> Is this typical for all MTB derailleurs? Or is it specific to bottom
>> pull, bottom swing designs?
>
>MTB derailleurs have a longer arm (and hence require more cable pull) than
>road ones, so conventional (bottom swing) MTB derailleurs like yours are
>more likely to foul a mudguard.
>

It's not just that it's longer. It is angled further to the center of
the bike compared to a road FD, and so it starts closer to the tire
than the road FD. But whatever geometric changes lead to the problem,
it is definitely a problem for me.

>It's generally not a problem for 'top swing' or top-pull derailleurs,
>because they have the lever arm in a different place.
>
>> Would a bottom pull top swing avoid this problem?
>
>Yes, almost certainly. I used a bottom-pull, top-swing XTR 950 model to get
>around this problem on my touring bike. The cable pulls the clamp down and
>to the right, away from the mudguard.
>
>James Thomson
>

Ok, thanks. How has the top swing held up? Looks likes a lot of pivot
points for slop and wear.

I have a top swing bottom derailleur on another bike- an Alivio. I
made some rough measurements as to how far back the pivots go from the
down tube and the relations between the pivots and the chainrings. All
in all- doesn't look very hopeful! But my frames aren't true touring
with long chainstays. Putting it in place would be the only sure
answer. Then I'll go by the LBS and see if other model derailleurs
have less rear projection.

Looking at the XT derailleur, looks like I could move the cable clamp
to the inside/front and gain 4 mm or so. Hmmm.... use a pan head bolt
in place of the allen and looks like no interference between the bolt
and clamp..... I knew there were reasons I liked not having indexing
on the front! This is the kind of thing that will send me to Campy if
I go to brifters.