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Front derailuer help

2K views 11 replies 3 participants last post by  thomllama 
#1 ·
I recently purchased a cheapo spare bike. I got one heck of a bike for $350 but it is a far cry from my Jamis Dakar 650b. I assembled the bike and had to make plenty of the usual adjustments. The rear deraileur shifts smooth, crisp and precise after adjustment. The front deraileur is a problem. It is crap... I adjusted it to perfection and it still shifts unpredictably and sloppy. The shifters are cheap but precise (Sram x4 trigger) and I am really impressed with how these cheap shifters work...the rear is absolutely perfect. So I will upgrade the front derailuer only. I want a mid grade derailuer since I don't want to spend much on this bike. Anything will be better than this POS suntour front derailuer.

I am confused about what type of front derailuer is compatible with my setup. Here is a link to the bike I have with specs:Mongoose Tyax Elite 2011 Mountain Bike | Evans Cycles

Any help is appreciated. Thanks.
 
#2 ·
You have a top-pull, bottom-swing front derailleur. Not sure what the clamp size is, you'll have to figure that out yourself. A direct measurement with a caliper is the best, but the size is often stamped on the clamp, and you could also figure it out by finding the circumference of your seat tube and dividing by pi.

Any Shimano or SRAM 9-speed or fewer FD that's top-pull, bottom-swing, and compatible with your seat tube will do. Actually I guess that narrows things a fair amount, but you shouldn't have too much trouble finding it. You could do top swing too, probably, but I've come to think that bottom swing is better.

For a bang-for-the-buck Shimano, I'd do plain Deore. For SRAM, I'm not really sure where the break points in function and service life are. But, whatever's equivalent.
 
#4 ·
Front derailleurs got a little narrower going from 8-speed to 9-speed drivetrains. However, the pull ratios are the same, so they're interchangeable. I did a 9-speed FD on a 3x8 drivetrain for a while myself, actually.

Front derailleurs for 10-speed drivetrains are a little different. There's a sticky on the top of the forum that lays it out. I haven't worked on any of that stuff myself. Since compatibility's broken, my current MTB will be staying 3x9 (or 2x9 maybe) for the foreseeable future.
 
#5 ·
Thanks for the help. I saw the front derailleur that came on the bike for four dollars on Jenson's website....that should tell you something!
I suppose I'm doing well since this is the only component that really needs to go. The rest of the components, while lower grade, seem pretty crisp and functional. I will replace them as they wear out.
 
#6 ·
Ya.. I'd look at the Sram X7 or better.. I like them a tad better than the Shimano's as they shift the cable pull and linkages out a tad to the side over the chain where the shimano's are more right behind the tube, gives better clearance to the tire and helps keep the dirt clotting lower... a tad ;) other than that either system works fine..

like AndrwSwitch stated you need a top pull, bottom swing ..if you search around, you can find some last yr's and older models on some pretty wicked sales.. most haven't changed all that much so the newer one's aren't any big thing worth the extra $$$ Especially on a bike like that I'm guessing you're usng as a 2nd/loaner/beater type bike ;)
 
#7 ·
I went with a Sram X9 top pull, top swing. I know my bike came with a bottom swing, but there is a threaded dimple with a bolt for a water bottle mount right above the derailleur. If I bought a bottom swing derailleur, and it was any larger than my current one (which is very compact), it wouldn't fit. I have lots of room from the threaded dimple all the way down to the bottom bracket assembly so any top swing will fit. Basically, having a low clamp mount will ensure that it will fit, whereas a high clamp mount could have been trouble.

Thanks again for all of your help.
 
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