gregjones

Several years ago I had ordered a high mount XT front DR for a new build. The mount band landed right at the lower boss for a bottle cage bolt. So, I used a low mount Deore DR to get around the problem.

I'm starting a new build and have found that the high mount DR will fit without any clearance problems.

Now the question.......

Is there any actual performance difference between a high and low mount DR. The Deore low mount DR has worked without problems of any sort and I would order another one it it would be better in any way. But...I do have the high mount DR laying around.

Thanks,
Greg

hermanchauw

For me, no performance difference. If it shifts precisely, it's good. It's not like brakes that you need more braking power at times.

corrado33

I'd imagine the low mount being slightly less bendy due to the location of the fixture, but otherwise probably the same in performance.

cyccommute 

They are called "bottom swing" and "top swing". The "high mount" is the bottom swing because it swings from the bottom of the clamp while the low mount swings from the top.

I prefer the bottom swing because it has more freedom of movement and the mechanism seems to have better leverage. The bottom swing derailer can move inboard further than the top swing because the parallelogram mechanism isn't hitting up against the frame. To me, shifts on top swings just seem a bit slower and requires more force on the shifter to make the shift.

A caveat: I only have 2 top swing derailers on bikes currently. One is a Shimano XT and the other is a Sram X9. The X9 works better than the Shimano but I've found that to be true of all varieties of front derailers. Shimano's cheap front derailers (road and mountain) are far better performers than their more expensive offerings but even their cheap front derailers don't perform as well as any Sram unit.

SkyDog75

Either type will work similarly as long as there isn't a limiting factor like a bottle cage getting in the way. Go ahead and use the derailleur you have laying around.

Generally speaking, if I'm grabbing a derailleur from the parts bin, I have a slight preference for bottom-swing ("high mount") derailleurs because the cage's inboard travel isn't as likely to be limited by the clamp and mechanism.

gregjones

Hey, guys. Sorry for the break in the thread. We've all (my family) have known for the last 4 years that mom would have to move. I did a bit at first and then laid back, still in the starting blocks for the gun. Every holiday I wondered if we are going to get started clearing out 60 years of stuff. No mention. So, last week the starter's gun went off and the race was on----we gotta get this **** outta here. No prob. I've got what I want, take all that's left. No good. I've spent the last week at mom's going through box after box after box of stuff. Those of you that have been there know full well what I mean. Mom reading letters from fifty years ago. Kept her busy and out of our hair!!

I knew that they were called something that I couldn't remember. So I looked on the Universal Cycles web page. Hell, they call them "High Clamp" and "Low Clamp". I even got that wrong. But, Stuart came up with the terms that I was looking for----high/low swing.

I have the XT, I hope High Clamp/Low swing on the frame and will carry on.

Thanks.

fietsbob

There is a top swing, bottom swing to various FD, too... traditional type is, high mount, top swing.

problem potential is with the index shifter cable pull not in synch with the cable pull requirement of the FD,

(friction shifting FTW, there, again)

bradtx

Greg, Now that the terminology is straightened out I haven't noticed any difference between shifting a top swing vs. a bottom swing FD.

Brad