Club Tour 517L Chainstay angle?

[Chris M]

Hello All

Does anyone know the exact chainstay angle on a 517L Club Tour?

I've just taken the two derailleurs off my Trek and cleaned them up ready to use on my Club Tour. On the back of the front mech it has stamped  'Chainstay angle 66 - 69 degrees'. I've not come across this before so did a search on Google to understand what it meant. After messing around trying to measure the angle I made a paper template cut at 66 degrees (seems to be the cut off point), it didn't fit so I made another at 63 degrees and it is a lot closer to the angle (I think??). Before I start searching for a suitable XT derailleur it would be good to know the exact angle.

Cheers

Chris

Edit: After some searching I've now ordered a new front derailleur from Rosebikes; Shimano FD M773. Hopefully it's the right part, 9 speed, 48 T compatible, 63-66 degree chainstay angle.

[Danneaux]

Hi Chris!

I'm afraid I don't know those angles; I could come pretty close by photo-scaling, but I don't see a 517L in the brochure. I get 65° on the 533S and 63.5° on the 620S.

I think you'll be fine with your replacement, Chris. For a good explanation of why/how chainstay angle is important, particularly for suspended MTBs, scroll to the bottom of this page: http://www.radon-bikes.de/xist4c/web/Technics-FAQ_id_9341_.htm

Best,

Dan.

[Chris M]

Thanks Dan

I hadn't realised before today that the angle of the chainstay was important to which derailleur was used. It seems another problem is that the derailleur can hit the actual chainstay when on the inner ring if the wrong angled one is used. Hopefully I have it covered now.

[jags]

this is a new one on me,i taught the adjuster screws on the rear mech were for that purpose

[NZPeterG]

Hi All
This angle has been around for years, Its the ideal angle the maker of the derail would like for it to work at its best.
Its like the rear derailleur, the maker say fit it at this point to the axle.
But the bike maker designs the to look good to them and this point is NOT at the same point the maker of derailleur said is best! this is why some bikes change better.

Have Fun..

Pete......

[Chris M]

this is a new one on me,i taught the adjuster screws on the rear mech were for that purpose

jags, it seems the bottom of the cage can hit the top of the chainstay. The one I've ordered has a modified cage to avoid this.

[jags]

chris any chance you could post a photo of this  honetly never heard of it before .
i never has any issues with rear mechs on any of my bikes.

[Chris M]

jags I have no photos. This only came about after noticing the chainstay angle stamped on the rear of the front derailleur and trying to check the angle on the Club Tour. Realising the chainstays were outside the range on the derailleur I started searching on Google for an answer. I found the bit about the derailleur hitting the top of the chainstay here;

http://www.bikeforums.net/archive/index.php/t-641732.html

http://bicycles.stackexchange.com/questions/17220/selecting-a-front-derailleur-parameters

Rather than trying to fit the M771 I have and finding it didn't work properly, I ordered the M773 to match the chainstay angle. For all I know, the M771 might have worked fine but after reading about possible problems thought I'd rather not try in the first place. Like yourself; this is all new to me.

[jags]

i used the xt m770 on the sherpa never missed a change..

[Danneaux]

this is a new one on me,i taught the adjuster screws on the rear mech were for that purpose

Jags,

It is all about how the upper run of chain approaches the chainring through the rear of the front derailleur *and* about chainstay clearance. With rear-suspended MTBs, the swingarm pivots through a range of motion, where on a road bike the rear wheel/chainstays are frigid. The angle rating on the front derailleur is to ensure proper shifting by having the chain pass the little bumps formed into the inner cage plate.

Chris showed a lot of foresight in checking.

There's a different but also important factor to watch for with front derailleurs, wrt mixing road and MTB drivetrain components: Chainwheel sizing. Using a road bike front mech (say, sized for a 52T chainring) on a compact MTB triple (with, say, a 44T outer 'ring), the rear of the road mech will hang out a in space, making shifting a bit lazy. Go the other way and fit a compact MTB triple to a large outer'ring and the cage contour won't match the 'ring very well.

I prefer half-step and granny gearing, but it has become tougher over the years to find a suitable front mech. Indexed chanring setups are all maximized for crossover gearing, and use front derailleurs with a deep inner cage plate. These foul the side of the middle 'ring on upshifts when used with a half-step. Just one more thing to watch for if you deviate from the narrow path of drivetrains engineered to work as "systems".

Best,

Dan.