Originally Posted by
muni50
Hi,
I have a Deore LX Front DErailleur.
I am looking to replace the crankset because the chainrings are worn and also I have a stuck pedal. The chainring is 52-42-30 (in the crank is written FC3304 and in the largest chainring "Shimano SG A-52). In the rear, I have 8 speeds.
I am struggling to understand the compatibility between FD and crankset (and rear cassette?) Here are my issues:
1. From Shimano's page the specs for the DEore LX FD, it says 'Applicable front chainwheel = 44/48T' . How can this be, if I have clearly been riding with a 52 chanring? Should I buy a new cranset with max 48 or 52 teeth?
2. I would like to have actually only 2 speeds instead of 3. What are the considerations apart from the 48/52 question above? DO I need to change anythign in the back cassette e.g. from 8 to 9? Do I need a new FD or will the Deore work with 2 speeds?
Thanks a lot!!
1) front ders are the least complicated mechanical item on a bike. the difference is in the cage. a road der will have a larger curvature to match the larger ring diameter. a compact mtn f der will have a smaller curvature to it. as long as you dont want to use a compact mountain der to shift to a 52 ring, you can probably make it work. most f ders have a bit of leeway through height and angle adjustments. you can also the bend the cage if you know what youre doing. also road and mtn ders have different cable pull and ders for triples have more travel.
2) try not to think of cranks as for "road" or "mountain." try to think only of the gearing you desire, the crank length you need, chainline, and compatibility. in your case the main issue would be chainline. a double would require a narrower bb spindle. depending on the crank you get, it may come with a new bottom bracket so your issue is solved. if you want to keep your old bb, you have to find a triple with the same bb interface as yours.
you dont need a new f der if you stick to a crank with similar size rings and the performance was acceptable to you
i think a 24/36/46 110bcd crank is ideal for most people. this is considered a compact road but is a very traditional size used by tourers and mountain bikers. the benefit is the abundance of chainring sizes, and the wide range of very usable and realistic gears. if you dont need the granny, remove it. i would recommend a crank without built in granny tabs for that.
"compact" refers to the bolt circle diameter. different bcds allow for different min size rings. your current 130bcd allows for a min 39min. a compact road has a 110bsd which allows a 34 inner and something smaller than a 52 outer ring - something many people find useful
btw, are you aware that the left side pedal loosens by turning to the right? that might be the source of your stuck pedal.
http://www.rivbike.com/Cranks-Chainrings-s/41.htm