Chris0381

Not not a serious heavy MTB'r but I enjoy hitting the rocky and woody trails. I purchased a used 2004 Trek 4300 and did the following changes.

New:
SRAM PG-850 with power link chain. $30
UN-73 BB $20
SUGIMO XD-300 crank 26/36/46T $50 edited 26 was 25
XTR Derailleur used $30
Stem riser to raise bars for touring $20
New wheelset with slicks to swap out for touring $80
Bar ends for touring $20
Sigma 850 Cyclo computer $15
6 ft Home Depot 3900 lb pull high vis plastic coated chain $10 (home storage)
Heavy duty MasterLock $8

Tools: Priceless

Everything works fine and wondering if it may be worth swapping out the Alivio Rear derailleur; and if so, what would you all recommend for this 8-speed bike.

FYI : I wont be upgrading to 9-speed in the future.

I'm just in the mood for upgrading if its not too expensive as its a fun project. Keep in mind, its not top of the line bike so $100 + derailleurs may be an overkill. So far I've done all the work myself and enjoy working on bikes.

My local Bike shop here in Berlin CT has been more than great.

Later on Ill ask for fork upgrade advise.

Thanks

maddmaxx 

An LX should handle this without breaking the bank.

Chris0381

Thanks ther Mad one. I like it. Ill look into an LX.

The model LX M581 has a 45T total capacity is this the largest chain ring and if so can I squeeze it onto a 46T chaninring bike.

ZeCanon

with proper chain length and as long as you're not running something stupid in the rear like a 36, yes.

JiveTurkey

Total Capacity = Chainring Difference - Cog Difference

45 = (46-25) - Cog diff.

Cog diff. = 24

(Always show your work!)

There aren't many wider cassettes than 11/34, so you should be fine. Make sure your chain length is as short as possible (for better efficiency), but just long enough to handle all the gear combos (wrapped just around the largest chainring and cog, w/out the derailleur, plus one link).

Chris0381

Yea Turkey. I removed a link today becase the chain was rubbing afgainst the RD cog while on the lowest cog and lowest chain ring.

I have the chain as short as it will go before removing the S-Bends on the RD cogs while on the bigest cog and bigest chain ring.

I found this

The total capacity is calculated by subtracting the size of the smallest chainring number from the largest chainring and adding it to the difference between the largest and smallest cog in the rear.

Present Total capacity = (46-26) + (32-11) = 20+ 21 = 41T

The Alivio has atoal capacity of 39T and thus may be justifcation or an upgrade a it is working fine though; but may explain why it bottomed out on the chain when on the 2 smallest gears.

The LX looks great.

Thanks

JiveTurkey

If you want decent and inexpensive, Nashbar.com has the Deore RD-M510 for $16 (one step below LX): https://www.nashbar.com/profile.cfm?c...%20Derailleurs

It can handle an 11/34 cassette, so it has a total capacity of at least 43.

By the way, capacity has to do with how much slack the rear derailleur can take up. If set up with the correct chain length, any rear derailleur can handle the highest gear (largest chainring/smallest cog), but if the capacity of the drivetrain exceeds the rated capacity of the derailleur, the chain will rub itself near the lower pulley while in the lower gears (as you noticed with the Alivio). Generally speaking, the longer the cage of the RD, the higher its capacity.

Chris0381

Sounds good there Gobbler.

Any way someone can provide a schematic so I can tell the difference between direct and non-direct attachment. Right now mine wraps around the axel at the dropout just like a run of the mill stadard bike. Can I use either ?

JiveTurkey

Hmm, having a little trouble understanding exactly what you mean.

Are you talking about where the rear derailleur attaches to the frame?

Chris0381

I was confused.

I thought I had the old style were the claw was part of the derailleur. I just looked at it and realized I remove the derailleur using an allen key. I hope Im right and that the spring will not unwind on removal. Im used to the old fashioned 10 speeds.

So what Im asking is no matter what model of shimano I choose, they all connect the same and wont have to worry about a specific model number except for SGS or GS.

Cyclist30907654

you won't notice a difference between Alivio and Deore. Jenson sells XT derailleurs for insanely cheap.

JiveTurkey

I thought you might have been talking about the old 10-speed style. You probably already know this, but you likely need the SGS (long cage) model of any derailleur. Well, good luck in your upgrading, whichever you go with. I have a Deore rear derailleur now, and will be saving up for an XT shadow.

Chris0381

Looks like Im good to go. Im looking for an XT or XTR myself if I can get a used one in good condition.

Yep SGS is what I need.

With winter on coming and the bike doing well now, I'll just be patient. I expect the ebay buying bids to dry up in the winter or stores looking to move old stock or maybe even a police auction.

JiveTurkey

Sounds like a good plan, though if I were you I'd be annoyed with the chain rub in the lowest gear and get the Deore for now b/c it is so cheap.

Chris0381

actually the chain rub disappeared when I removed a link. I get no rubbing at all but I have spent a lot of time learning how to adjust derailleurs and trial and error with positioning.