hi im 6'4'' and 295 lbs i live im minnasota and ride my bike year round. so as you could imagine my bikes have issues. plus i ride long distances. so i was just wondering if there were any super heavy duty parts ie cranksets. derailures axles etc that are not totally expensive(still in hs). my mt bike before it got ripped off had gone through 4 rear derailures and one front one, 8 chians, 2 rear cog assemblys and about 25 broken spokes. all becouse i was doing something dumb or it was really cold (broke the spring in my rear derailure when it was 35 below and cracked one in half when it was 28 below).so its not like it was the manifactures fault.

Well my guess is you aren't shifting as well as you could, IE, not shifting under load. You want to learn to soft-pedal when you shift so you aren't as stressful on the chain and drivetrain... thats a huge cause of failure and is really exaserbated by a larger rider.

For durable stuff, look into downhill and freeride parts. They aren't cheap but they are strong. Best value in wheels are Sun Ryno Lites on Shimano hubs... you can get a set for under $200 usually. Cassettes, just get a LX or XT cassette and thats about as good as they get. For chains I always buy SRAM, but the Powerlink system I think may be a problem for big riders.

Raceface for example provides guarantees against failure on some of their components...even if the rider breaks them by doing something crazy. Such components would be expensive initially, but if you break as many components as you say you do, this might be cheaper in the end.

What exaclty is soft pedalling?

Opposite of hard pedalling.

Soft pedalling is when you choose the right gearing to not mash on the pedal. Bmxers mash...roadies spin (pedal softly)...

Soft pedal is where you build some momentum just before a shift then you lower pressure on the cranks during the shift then continue normal pressure after the chain makes the transition. This is especially helpful when making chainring shifts.

At temperatures that cold, the steel parts on your bike begin to get brittle, so you need to be make an extra effort to be gentle on them.

my major problem is that i slide into stuff and i cant use studded tires. after my first derailur i was told and shown how to soft pedal so i know how to and i implement that. the lbs dude told me about saint gear anyone know or heard anything about it

What time period is this in? I am 6'5 and 270...and over a year period. What you have gone through is not unreasonable for example. You like have strong legs and with the weight a lot of torque. (although a properly built wheel should easily take most of what a person can throw at it. I can do 5 footers and don't go through 25 spokes )

Either that or your lbs is scamming you. Going through deraileurs is hard without first breaking a deraileur hanger. And for him to mention saint seems ridiculous. That is extremely overpriced and meant for serious banging (freeriding)...what exactly was wrong with your deraileurs...chains and cogs are easy to go through, I tend to go through them faster because I am not the best pedaller through rought stuff.

Rear wheel...25 spokes...at various times?A competant mech should have told you to buy a new rear wheel, handbuilt on a heavier rim. Either that or a complete rebuild. Once you break a few spokes you can very rarely FIX the problem. What rims were you running.

It sounds like your shop a) doesn't know how to deal with heavier riders and their needs and b) does know how to deal with breakages similar to fr usage.

So lets start there.

Man, your a big guy. Have you looked into the single speed revolution? This would solve many derailluer issues

I couldn't imagine as a heavier guy trying to do long trips on a ss...

I suppose a problem with the wheels could be to blame for the spokes, but I'm thinking cold weather is just as likely of a likely scenario.

When steel gets cold, it undergoes a "ductile-to-brittle" transition. The effect is measureable at higher temps, but it only becomes significant when the temperature is below freezing. The result is cold steel parts can't bend as far before cracking as warm steel parts. Rather than being able to bend pretty far under an excessive load, they just snap. This effect probably contributed to the sinking of the Titanic and actually caused several Liberty ships to break in half spontaneously during WWII. Springs and and spokes are already made from pretty hard steel alloys, which are already relatively brittle, in spite of taking more force to bend. Good alloys will withstand lower temperatures better, but 35 below is probably enough to begin effecting any steel. I think some titanium alloys do not undergo a ductile-to-brittle transition, but I doubt you could find titanium deraileur springs.

Use heavier spokes if you can get them. Keeping your tire pressure a little lower than normal may help by reducing the stress from going over bumps. I don't know what to do about the derailuer other than keep the bike inside when you're not on it, so it will be warmer, and avoid excess shifting once it's cooled down so you don't stress the springs as frequently.

I would definitely be interested to hear if other riders in cold climates have experienced this, as well.

as far as the rear derailleur goes, perhaps something more uplevel like the new XTR or the SRAM X.0 would work better in such severe conditions? The X.0 says it has a titanium spring.

one other thing to keep an eye on is your bars.... When I got my new bike, I looked at my trek and the bars were cocked to my dominant hand. Also, If you don't ride smooth, as I dont, watch your saddle. The rails on a saddle not meant for big guys can bend pretty easy.. I ride a Haro BMX saddle now, think the rails are 9mm as opposed to 8mm.

As far as the derailleur, could you mod a lizrd skin to make a little coat for it, that wouldnt impede function, obviously? That would keep off the ice, block wind chill, and keep in any heat generated by the friction inside, though it may not be much if any.

Just an idea.

How many spokes does your rear wheel have. Big guys should use at least 36. A touring grade, handbuilt wheel would have 13/14 guage butted spokes. This type of wheel is not very expensive, esp compared to the exotic pre-built ones.
LX and XT are both good strong bits of kit. XTR has a lot of lightweight material, eg Al instead of steel axle. Its a few grammes lighter but not neccessarily any stronger.

Thank you cyrogenic. I just checked out SRAM's website and it does say the extension spring is titanium. Unfortunately, the X.0 is about $150 and the site doesn't say anything about the other springs in it being made from titanium. Also, it turns out not all titanium alloys are as resistant to cold. I guess I could be going down a dead end. Perhaps if you were able to talk to an engineer from SRAM or Shimano, you might be able to find out which, if any, of their products are appropriate for extremely cold temperatures. The worst that could happen is their customer service rep says "We don't have that information and our engineers are busy." The best would be for either company to design their parts with cold weather in mind or make available cold weather springs and pins, etc for replacement.

Almost forgot. Aluminum alloys undergo almost no ductile to brittle transition, so some aluminum parts will fair better than steel counterparts in cold weather. Alas, it makes crappy springs and doesn't work as well as steel for parts that move, like cogs.

Also

Anyone remember the Grunge Guard??? It was a rubber cover for the rear derailleur to keep, well, grunge out of the moving parts. I would imagine that would work.
https://www.cambriabike.com/SALE/dera...unge_guard.htm

holy **** it DOES exist!

For a crankset it's hard to beat a Truvative Hussefelt mated to a Gigapipe Team DH bottom bracket. Beyond that I agree with what seely said.