Front Derailleur questions??? My new frame

[Scott]

 will use a 34.9 clamp top pull. How do I tell if a top swing or bottom swing is required? Also, how compatible is the 9 speed f.d. with my 8 speed drivetrain? I read that the chains are very close to the same width. Front shifter is a SRAM Plasma which allows me to "Trim" or fine tune derailleur position.

Thanks,
Scott

[jimbo]

Which frame?

I used a 9-spd FD with a 8-spd chain.  It does work and using gripshift micro adjustments does make it easier to dial in.  However the 8-spd chain is wide enough that you need to micro adjust the front derailleur more often than the 9-spd chain.  I eventually switched everything to 9-spd so the FD did work better.

[debaucherous]

Top swing vs bottom swing - refers to whether the cable comes down from the top tube, or up from the bottom bracket.

[Scott]

Thanks, I have SRAM shifters too.  I confess, I have bought outside the K2 ProFlex line.  It's the Italian Extralite F1 and @ 20 cents on the dollar (new)I could not resist.  Specialized had bought it to study and see what they could adopt or should not, and it was never built up.  It was then sold to an employee. http://www.extralite.com/index_usa.htm

[tmaybee]

Hi Scott.  Front deraileurs are a bit complicated.  

Firstly, there is top pull and botton pull.  This refers to where the cable is pulling from.  A top pull der will have cable routing that comes along the top tube and pulls up on the der.  A botton pull der will have the cable running under the bb and pulling down on the der.

Secondly is top swing and bottom swing.  The top swing der is the style that came out with the M950 series.  Here is a pic:


Botton swing is the older style. (although I think 2003 XTR has gone back to bottom swing)  Here is a pic (and this also happens to be a bottom pull)


This is a bottom swing, top pull model.


And there is one other model called the e-type.  This just referrs to the mount.  It mounts directly to the bb shell.  I think they are only avaliable in top swing.



If there is something that will limit how high you can position the front der on your new frame, I would go with a bottom swing.  I cannot use a top swing on my 856 because of the hole (for the cable to pass through) in the seat tube.

Hope this helps.    

Trevor

[RhinoDave]

After looking at the website it looks like the derailer on the F1 is a top swing top pull. The picture is from the non-drive side and you can see the clamp is located well below the outer chain ring. Also you can see the cable routing on the complete bike or the cable stops on the frame pic. Most interrupted seat tube bikes will use either a top swing or e type derailer.

[Simon]

Shimano 9 speed chain pin width is 6.5mm, 8 speed chain pin width is 7.1mm,the  9 speed f/mech is narrower than an 8 speed f/mech but the same width as an old 7 speed mech.Simon.

[Scott]

Thanks everyone-this site is a great help!  I'll start looking for a 34.9 top pull top swing 950.  I'll post my impressions of this bike vs. the Oz as soon as I have it built up -and our 3 feet of snow melts too

[tmaybee]

Hey Scott, are you going to use your Fournales fork on the extralite?


Trevor

[Scott]

Hi Trevor,

Yes, at least at first and then in comparison to the Mega Air I picked up.  It's possible the F1 Extralite is harsh enough out back to require the extra plush of the Mega Air but I don't know for sure.  Certainly the Fournales would look the part on the Extralite!  If you're interested in that fork I can email you should I decide to sell?  I have a spare pivot kit too.

[tmaybee]

Hey Scott.  I think the Fournales fork is a bit beyone my budget at the moment.  I was considering possibly picking up a mega air because they are SOOO cheap.  

Of course, after investing $500+ USD in crosslinks and bushing kits in the past year I am in no rush to switch forks.  Maybe for my 955?  

How do you like the mega air compared to the crosslink?

Trevor

[Scott]

Haven't mounted it up yet-and besides the weather around here gives evey sign of not sending anything like spring this way for another YEAR!  The way you've setup your Crosslink has it nearly the same, weight wise, as the Fournales so I think you'd be duplicating things with a Fournales.  There are differences in handling (wheel trajectory) but nothing hugely distinct.  There's some lengthy talk by riders with a lot of time on Mega Airs over at the Save Some Weight board,  that and the input here is  what caused me buy onel.  $99 helped too!