Need Help Selecting Crankset

Race Face cranks ARE very, very good ... If the question is what length crankarm to get, then 175mm is probably the length of the crankarms which are currently on your bike -- if you look at the side of the crankarm which faces inward, then you will probably see the size stamped-or-etched near the pedal (e.g., 175) ... [INDENT]You will want the "68/73mm BB" (really, the BB shell's width) ... [INDENT]I believe that the "83mm BB" is for real Downhill bikes whose frame's are typically designed for a single chainring[/INDENT] [/INDENT] BUT, the Race Face CHESTER is a Downhill crankset which is intended for much more robust riding situations than you are currently planning ... and, your bike's frame AND fork (in particular) would probably not be able to withstand the rigors of a real Downhill run. In other words, putting THAT crankset on your relatively plebeian bike is quite a bit of overkill ... BUT, if you chose the Race Face Chester for its appearance, then [B]go for it![/B] BTW. I am under the impression that the Race Face Chester crankset does NOT come with chainrings. [INDENT]Personally, I would probably opt for a set of SHIMANO XT or SHIMANO SLX cranks + a set of Shimano Hollowtech II Bottom Bracket cups ... With the XT typicaly being my preference mostly for cosmetic reasons simply because the painted-silver arms are what I am used to looking at (!?!), but I don't know what the cosmetics on the currently available XT cranksets looks like ... however, if 'I' wanted a crank with a darker spider, then the SLX would probably be the better option ... [INDENT]FSA MegaExo cranks would be a more economical choice than either of the fore mentioned Shimano cranks ... [/INDENT] BUT, a more pedestrian (WHY PAY MORE?!?) Shimano Deore (vs. Deore XT) crankset may be the wisest choice from an economic stand point ...[/INDENT] BTW. What is broken on your current crankset that cannot be replaced?

Thanks for such a thoughtful and complete reply, Alfeng.

I should mention I grew up riding 20" BMX bikes, and I do tend to be hard on my mountain bike even commuting. I like to hop small obstacles and just have a good time when I ride. I do ride downhill single track on occasion, but nothing too big or technical.

I was wanting to spend a little more money on a crank, even though I think it may be overkill, because I always seem to murder them; and I like things to last. I might be able to repair the existing crank, but it has slipped and come apart regularly since day one. I locked the rings in with some locktite a few months back, and they've come apart again, and I'm sick of fixing it. I want something that will handle the torque my legs can put down, especially when climbing.

I was drawn to the appearance of the Chester. I wanted something that would be easy to replace within the context of my existing setup, but you got me thinking. Why do I need a triple up front?... I only use that top front gear when I ride, always.

Do you know of an option more like this crank, but designed for 8 speeds (and then I can just drop my front derailleur and shifter and altogether):
http://www.amazon.com/gp/product/B007YH87CK/ref=ox_sc_act_title_6?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

Thanks for helping out the noob! 🙂 Mechanical components are not my forte.

P.S. Is the frame really that weak? I was thinking about upgrading the fork down the road as well.

The Race Face Chester crankset should be good-to-go choice for a single chainring installation on your bike ...

You just need to use EITHER BMX chainring bolts OR mount a chainwheel "guard" (typically, but certainly not always, with a Single Speed on a MTB-or-frame-with-135mm-rear-wheel, the chainring is mounted on the inner shoulder of the crank's spider which uses 104BCD chainrings [it's due to the greater offset engineered into the spider than on a "Road" crank's spider]).

BTW. Your frame probably isn't too weak, but "real" Downhill bikes are FULL SUSPENSION with a lot of travel (much more travel than you would find on a typical MTB's suspension), front & rear ...

• that is, "Downhill" is generally a fairly specialized classification ...
  

As far as a better fork, I recommend Marzocchi ... their strength is the source of their weakness -- they began as a manufacturer of motorcycle forks (which they still make), so I think that their MTB forks can (¿still?) be considered to be de-tuned motorcycle forks (well, THAT has been MY thinking) & they are consequently a little more robust (i.e., heavier) relative to comparable forks from other manufacturers [OR, maybe they just never cared about the weight of their products!!!] ...

In the now-distant-past (so, presumably the same may be true, now), for reasons which have never been clear to me, Manitou forks could not be rebuilt to spec (according to those how have tried) ...

Rock Shox is owned by SRAM, so THAT is a reason to avoid them despite the quality of the product, IMO ...

FOX & other brands are all probably very good, but 'I' don't know about their long term viability (re-build-ability).

Depending on the situation, I think that you might actually want to consider a 29er suspension fork ... although it will probably cost more, it will result in a slacker head tube angle which could be BETTER for descending (depends on how shallow/steep the inclines are) AND it will give you the future compatibility with larger wheels/tires (if THOSE are in your future) ... and, a slacker head tube angle will probably not be (but, no guarantees) an uncomfortable angle for your daily pavement riding.

BUT, you may want to wait until you know that your bike's current fork is unsatisfactory before replacing it ...

1. it bottoms out too easily
   
2. it is too bouncy
   
3. et cetera
   

Expect to pay MORE THAN $250 MSRP for a reasonably good suspension fork (more like $400+, MSRP ... buy last year's model to save some money ... check MTBREVIEWS.COM) ... when in doubt, don't cut the steerer too short [leave an extra (?) inch] because you can always move it to another frame, later and you never know what the head tube length may be ...

Thank you!