Braze-On Front Der Won't Adjust Low Enough for 50t Ring.



5

55/Rad

Guest
Frame - Trek OCLV 5500. I want to install a compact crank but the 6500
Ultegra braze-on front derailleur won't adjust low enough for the 50
tooth big ring. It will only get to within a half inch or so.

Any suggestions? Can I modify the bracket in some way? Is there an
adaptor or a different hanger somewhere to be purchased? Is filing the
slot or getting a custom made hanger the only option?
Thank you in advance.

55/Rad
 
55/Rad wrote:
> Frame - Trek OCLV 5500. I want to install a compact crank but the

6500
> Ultegra braze-on front derailleur won't adjust low enough for the 50
> tooth big ring. It will only get to within a half inch or so.


Just get it within a half inch and ride the bike. The front derailleur
will shift the chain between the chainrings just fine. It does not
have to be exactly 2mm above the outside ring to work. Nor does the
curvature of the derailleur cage have to precisely match the curvature
of the outside ring to shift properly.
 
Ummm ok. However, the last time I rode a bike with enough space to
throw the chain, guess what...it threw the chain. And I ended up in the
hospital getting sewn back together. So I'm sure you'll understand why
I'd like my der to be a little closer that just "in the neighborhood".
55/Rad
 
55/Rad wrote:

> Frame - Trek OCLV 5500. I want to install a compact crank but the 6500
> Ultegra braze-on front derailleur won't adjust low enough for the 50
> tooth big ring. It will only get to within a half inch or so.
>
> Any suggestions? Can I modify the bracket in some way? Is there an
> adaptor or a different hanger somewhere to be purchased? Is filing the
> slot or getting a custom made hanger the only option?
> Thank you in advance.


I've said it before, I'll say it again:

Front derailer braze ons are the work of SATAN!

Sheldon "Retro Me Satanas!" Brown
+---------------------------------------------+
| Whatever you say, say it with conviction. |
| --Mark Twain |
+---------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com
 
On 29 Dec 2004 16:13:03 -0800, "55/Rad" <[email protected]>
wrote:

>Frame - Trek OCLV 5500. I want to install a compact crank but the 6500
>Ultegra braze-on front derailleur won't adjust low enough for the 50
>tooth big ring. It will only get to within a half inch or so.
>
>Any suggestions? Can I modify the bracket in some way? Is there an
>adaptor or a different hanger somewhere to be purchased? Is filing the
>slot or getting a custom made hanger the only option?
>Thank you in advance.
>
>55/Rad


I got a 50 tooth chain ring on my Trek OCLV. The "special" Trek
bracket appears to be a re-worked stock one. So if you're handy with
simple metalworking, I recommend you consider carefully extending the
slot downward.
 
Sheldon Brown wrote:

> 55/Rad wrote:
>
>> Frame - Trek OCLV 5500. I want to install a compact crank but the 6500
>> Ultegra braze-on front derailleur won't adjust low enough for the 50
>> tooth big ring. It will only get to within a half inch or so.
>>
>> Any suggestions? Can I modify the bracket in some way? Is there an
>> adaptor or a different hanger somewhere to be purchased? Is filing the
>> slot or getting a custom made hanger the only option?
>> Thank you in advance.

>
>
> I've said it before, I'll say it again:
>
> Front derailer braze ons are the work of SATAN!


How would one braze a derailleur mount to a carbon fiber composite frame
tube? ;)

--
Tom Sherman - Near Rock Island
 
>>> 55/Rad wrote:
>>> Frame - Trek OCLV 5500. I want to install a compact crank but the 6500
>>> Ultegra braze-on front derailleur won't adjust low enough for the 50
>>> tooth big ring. It will only get to within a half inch or so.

-snip-
>> Sheldon Brown wrote:
>> I've said it before, I'll say it again:
>> Front derailer braze ons are the work of SATAN!


Tom Sherman wrote:
> How would one braze a derailleur mount to a carbon fiber composite frame
> tube? ;)
>

It's the jargon of our industry. We call anything that
doesn't encirle the seat tube a "braze on". Even when it is
a stainless steel plate bolted to threaded inserts on a
carbon frame. (Which, by the way is still the work of Satan.)

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971
 
I resolved this problem by taking a Mavic br-on front der and drilling and
tapping threads above the factory hole.

Mavic has a lot of extra material so it is safe. Other fr ders that I've
considered don't seem to be able to be safely modified.

If you want a Mavic fr der contact me.

I recently erred in specing a br-on on a bike I had built for me. I was
possessed by the devil. Definitely a mistake.

Gary Jacobson
Rosendale, NY
 
> Frame - Trek OCLV 5500. I want to install a compact crank but the 6500
> Ultegra braze-on front derailleur won't adjust low enough for the 50
> tooth big ring. It will only get to within a half inch or so.


Your dealer can order the new "compact drive" front derailleur bracket from
Trek; just got some last week. Haven't yet installed one on my own bike (a
5900) so the front shifting is probably a bit less than optimal, but still
seems to work quite nicely.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com
 
Russell
Perhaps we're talking apples & oranges here, but I've always had one
hell of a time getting a f. derailer to work when not as cllose as
plssible to the big ring. In fact I've usully fornd the f. derail hell
to adjust period. much harder than a rear, except for the last XT (a
2003) I installed. Probably spent < 10 min installing & adjusting.
Worked perfectly in the stand. I figured 'yeah, sure, soon as I ride
it, I'll end up spending hours getting it to work'. Worked absolutely
perfectly. Didn't have to touch a thing. Couldn't f'ing belive it.
You must be incredable good, or incredabaly lucky to get f. derails to
work w/ 1/2" gap & not throw chains.
John
 
Is there a photo of this new bracket anywhere on the web?
Thanks.
Gary Jacobson
Rosendale, NY

"Mike Jacoubowsky" <[email protected]> wrote in message
news:[email protected]...
> > Frame - Trek OCLV 5500. I want to install a compact crank but the 6500
> > Ultegra braze-on front derailleur won't adjust low enough for the 50
> > tooth big ring. It will only get to within a half inch or so.

>
> Your dealer can order the new "compact drive" front derailleur bracket

from
> Trek; just got some last week. Haven't yet installed one on my own bike (a
> 5900) so the front shifting is probably a bit less than optimal, but still
> seems to work quite nicely.
>
> --Mike-- Chain Reaction Bicycles
> www.ChainReactionBicycles.com
>
>
 
Capt Bike-<< I've said it before, I'll say it again:

Front derailer braze ons are the work of SATAN! >><BR><BR>

I agree but for this gent. Take the front der barazeon piece off, grind the
bottom of the slot so that the front der will go lower. You can also use a
triple front der which has a bigger cage.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"
 
Everybody - thank you for the suggestions. I'd be interested to know if
the special bracket from Trek is just the standard Shimano with the
slot ground open? Since I have the tools, I think that will be the
first thing to attempt.

Happy new year.

55/Rad
 
A Muzi wrote:
>>> Sheldon Brown wrote:
>>> I've said it before, I'll say it again:
>>> Front derailer braze ons are the work of SATAN!

> We call anything that doesn't encirle
> the seat tube a "braze on". Even when it is a stainless steel plate
> bolted to threaded inserts on a carbon frame. (Which, by the way is
> still the work of Satan.)


Fascinating church you guys belong to. I've heard of the churches of
Campy and Shimano (these preferences widely being seen as religious
issues), and the greased taperians and the anti-greased taperians, and
of course the tubulo-clincherian schism is widely known. Hadn't heard
of the anti-front-derailleur-brazeronians.

Actually, I'm rather fond of my newer bike's braze-on (really *braze* on
for me) front derailleur mount.

Mark "the devil made me do it" Janeba
 
On Thu, 30 Dec 2004 18:04:41 GMT, Mark Janeba
<[email protected]> wrote:

>A Muzi wrote:
>>>> Sheldon Brown wrote:
>>>> I've said it before, I'll say it again:
>>>> Front derailer braze ons are the work of SATAN!

>> We call anything that doesn't encirle
>> the seat tube a "braze on". Even when it is a stainless steel plate
>> bolted to threaded inserts on a carbon frame. (Which, by the way is
>> still the work of Satan.)

>
>Fascinating church you guys belong to. I've heard of the churches of
>Campy and Shimano (these preferences widely being seen as religious
>issues), and the greased taperians and the anti-greased taperians, and
>of course the tubulo-clincherian schism is widely known. Hadn't heard
>of the anti-front-derailleur-brazeronians.
>
>Actually, I'm rather fond of my newer bike's braze-on (really *braze* on
>for me) front derailleur mount.
>
>Mark "the devil made me do it" Janeba


Dear Mark,

Something about the holidays brings out the basest emotions
in Sheldon concerning brazen derailleurs:

http://groups.google.co.uk/[email protected]&rnum=1
or http://tinyurl.com/6vdey

Carl Fogel
 
Tom, a hi tech guy like you haven't heard of the "composite
construction" of brazing to carbon fiber. You should be ashamed of your
self. John
 
On 29 Dec 2004 16:13:03 -0800, "55/Rad" <[email protected]>
wrote:

>Frame - Trek OCLV 5500. I want to install a compact crank but the 6500
>Ultegra braze-on front derailleur won't adjust low enough for the 50
>tooth big ring. It will only get to within a half inch or so.


½" seems too much. The frame should handle a 52t ring and a 50 isn't
that much smaller. Usually filing a bit of metal off, when necessary,
works fine.
 
Paul Kopit wrote:
> ½" seems too much. The frame should handle a 52t ring and a 50 isn't
> that much smaller. Usually filing a bit of metal off, when necessary,
> works fine.


A 50T ring is about .159 inches (4.0 mm) less in radius.
(change in circumference/2Pi) If you're near the bottom of the braze on
slot, that could be a lot.

Agree about the filing, if you don't take of so much as to weaken the
fitting.

Mark Janeba
 
On 30 Dec 2004 08:00:56 -0800, "55/Rad" <[email protected]>
wrote:

>Everybody - thank you for the suggestions. I'd be interested to know if
>the special bracket from Trek is just the standard Shimano with the
>slot ground open? Since I have the tools, I think that will be the
>first thing to attempt.
>
>Happy new year.
>
>55/Rad


The Trek front derailleur bracket for compact cranks looks to me like
a modified standard one. I took a photo of mine:

http://www.geocities.com/dianne_1234/bikes/bracket.htm
 
> Is there a photo of this new bracket anywhere on the web?
> Thanks.
> Gary Jacobson


Gary: Not much different about it at all, except that it's a bit longer with
a slot that goes down further, putting the derailleur closer to the
chainring. Rocket science it isn't!

--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
IMBA, BikesBelong, NBDA member

"Gary Jacobson" <[email protected]> wrote in message
news:[email protected]...
> Is there a photo of this new bracket anywhere on the web?
> Thanks.
> Gary Jacobson
> Rosendale, NY
>
> "Mike Jacoubowsky" <[email protected]> wrote in message
> news:[email protected]...
>> > Frame - Trek OCLV 5500. I want to install a compact crank but the 6500
>> > Ultegra braze-on front derailleur won't adjust low enough for the 50
>> > tooth big ring. It will only get to within a half inch or so.

>>
>> Your dealer can order the new "compact drive" front derailleur bracket

> from
>> Trek; just got some last week. Haven't yet installed one on my own bike
>> (a
>> 5900) so the front shifting is probably a bit less than optimal, but
>> still
>> seems to work quite nicely.
>>
>> --Mike-- Chain Reaction Bicycles
>> www.ChainReactionBicycles.com
>>
>>

>
>
 

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