Front derailleur adjustment for tall riders

[yangmusa]

I can't be the first tall rider to have this problem, but I can't seem to find posts related to it either (sorry if my search mojo failed!)

I'm 6'4" with long legs, and I have the TFT on my Sofrider extended a long way (around the 10 mark, but it looks like it could extend even further. This means that the TFT and chainstays are at a fairly accute angle to each other, and consequently the front derailleur is operating outside it's intended parameters. When I shift into the big chain ring, the chain rubs on the underside of the derailleur (see photo). I'm only just learning to ride the bike and haven't needed the big ring much, but found that there was already a dusting of metal filings accumulated from the chain/derailleur grinding on each other.

Suggestions for how to eliminate this problem?

Thanks!

 

[Andrew 1973]

I think I know...

If I'm incorrect, someone please feel free to correct me. I recall that this is a problem when fitting the Sofrider for taller riders. If you look at the S30 Silvio and V20 Vendetta, you will see that the derailleur is mounted on a stalk that is independent of the boom tube. Prior versions of the Silvio had multiple FD mount points attached to the boom tube to counter this problem.

That said, you can get around this issue by replacing the FD with a different type. While it may be finicky to adjust, a triple FD may work due to its particular cage shape. Unfortunately, finding one that works is a bit of hit or miss and that can be costly to try several.

Perhaps a FD mount that attaches to the BB is a solution, but I think they ate designed to be used with external cups, and that would require a new BB and crankset. I probably haven't helped much, but this is what I know.

 

[yangmusa]

Eric - there's a lot of

Eric - there's a lot of clearance when on the small ring. To be clear, the interference is on the underside of the derailleur (affected by derailleur mounting location) and not on the sides (affected by high/low adjustment screws).

Andrew - I'll take a close look at some Silvio pictures and see if I get any ideas.

 

[Eric Winn]

What happens on the other end

What happens on the other end when in the small chain ring?

The FD mount should have some adjustment range to split the difference between the extremes for big and little chain ring. You might end up just rubbing at both ends but you might be able to find a position that just avoids rubbing for both rings.

Edit: Is the FD mount on a Sofrider a bolt-on? I've only messed with brazed on mounts. Can you move the bolt-on up just a smidge?

-Eric

 

[ratz]

A long cage should did that..

Same problem with the quickr when I converted the quest to traditional gearing. My problem was on the other extreme going sub position four. You can switch to a clamp on triple front derailed from a road bike. That will have a longer cage. If that does work you can get some exotic long cage front derailluars.

 

[cllsjd]

Derailleur

Eric,

I'm 6' 2" and I had sort of the same problem on my older Quest. As I pushed the bottom bracket forward the derailleur was dragging on the chain stay. I moved the derailleur up until I had clearance. That is not how the derailleur is supposed to be positioned relatively to the chain ring and the chain fell off the outside frequently when shifting from the middle chain ring to the big ring. To prevent that I fashioned a chain keeper from a piece of aluminum. Maybe not how it is supposed to be, but I've ridden thousands of miles without problems.

Chuck

 

[Rick Youngblood]

I'm sure Eric is asking

I'm sure Eric is asking whether or not the chain is on the largest cassette cog. Most likely yes (big x big), this is where the chain will hit the bottom of the top portion of the FD.

Assuming the FD mount can't be moved back to give chain clearance. Andrews solution may be it. Some brase-on FD have two mounting holes, my SRAM does, so I'm able to move the FD way back and clear very large chainrings.

Look and see if your FD has a second hole, if it does you may be in business.

 

[yangmusa]

Problem solved... ish. I

Problem solved... ish. I moved the derailleur further away from the crank about 1" and found I had lots of clearance. So I gradually moved it closer until the clearance is as small as seems prudent. I can run both large and small chain rings with no problem!

The downside of having the derailleur closer to the cassette is that it's very sensitive to "rear" gear choice - I just did a shakedown ride and found I had to constantly trim the front derailleur to avoid rubbing. Oh well, it isn't that bad and now I can use all my gears, at least.

 

[Andrew 1973]

How's Your Shifting?

With the front derailleur so far from the chainrings, I am curious as to how the shifting is performing. Typically, depending on the manufacturer, the recommended distance is 1 - 4mm from the highest point of the teeth of the outer ring. If you find shifting to be greatly compromised, Sram offers an angled shim that just might give you enough clearance so that you can run the derailleur closer to the rings.

Check out this link to view. (opens in new window)

 

[1happyreader]

awesum angle

Yeah ,,,, Andrew,,

that's a great asymmetrical find !!!!!

 

[Andrew 1973]

A Rather Spendy Shim

At $11.99, it's an expensive little sliver of alloy. I imagine some folks here would prefer to make their own.

 

[jimbo3b]

I had the same problem

I'm 6'4" also, although more of my height is in my torso, so I don't need the bottom bracket out quite as far.

I tried a triple on the front of my Sofrider for a few months. My problem was at the other end, the bottom of the cage would hit the chainstay when shifting down. I knocked the paint off the top of the chainstay and bent up the derailleur. When I went back to the double rings that problem was solved, but I still have to trim the front derailleur depending on the rear gear.

 

[Charles.Plager]

Hi Jimbo,
Did you replace the

Hi Jimbo,

Did you replace the bottom bracket when you put on the triple? I found the stock bottom bracket wasn't wide enough for a triple (upgraded to 123mm wide square taper).

Cheers,
Charles