Chainrings?

[MOHSHSIHd]

So my big ring is bent, and pretty much trashed....from what I can gather it is a Supershift III.....its got 42 teeth, is that all I need to know to get a new one and put it on?


I am the ultimate bike jong, so bear with me

[BLOODSWEATSTEEL]

No. You need to know the bolt circle diameter, the number of mounting bolts [4 or 5,] and if it's a 7/8 speed or 9 speed rear also.

You'll prolly need a little chainring bolt-holder-thingy [for lack of a better term] to get the bolts off with as well. About $2 at your bike shop. They'll know what you're talking about.

[dfinn]

No. You need to know the bolt circle diameter, the number of mounting bolts [4 or 5,] and if it's a 7/8 speed or 9 speed rear also.

You'll prolly need a little chainring bolt-holder-thingy [for lack of a better term] to get the bolts off with as well. About $2 at your bike shop. They'll know what you're talking about.

I've had OK luck using a really big flat head screw driver as the "bolt-holder-thingy", but I recently bought the proper tool for $2. Mosh, once you look at the back side of the bolts that are holding the ring to the crank you'll have a better idea what we are talking about.

what are the options for bolt circle diameter? i've never heard of this before.

[pechelman]

correct me if im wrong, but its usually stamped somewhere on the drive side crank near or on the spider

[homerjay]

Shimano is 104mm.

I've had luck with banging my big ring back straight with a hammer, but that's kind of a temporary solution.

[BLOODSWEATSTEEL]

what are the options for bolt circle diameter? i've never heard of this before.

Common outer BCD's -

130mm - road
135mm - road [Campy]
122 - Stronglight road

110mm 5 bolt - mtb
94mm 5 bolt - mtb compact

146mm XTR M960 4 bolt
112mm XTR M950, M952 4 bolt
104mm XTR [forgot the series,] XT, LX, Bontrager 4 bolt

I'm sure there are more....

[MOHSHSIHd]

No. You need to know the bolt circle diameter, the number of mounting bolts [4 or 5,] and if it's a 7/8 speed or 9 speed rear also.

You'll prolly need a little chainring bolt-holder-thingy [for lack of a better term] to get the bolts off with as well. About $2 at your bike shop. They'll know what you're talking about.

bolt circle diameter I cant find, but its 5 bolt with an 8 speed rear....

thanks

[MOHSHSIHd]

Shimano is 104mm.

I've had luck with banging my big ring back straight with a hammer, but that's kind of a temporary solution.

oh really?


hmmmm....Ill try the hammer method until I have some loot...

im guessing my stuff is shimano cause my components are shimano? or is that a moronic assumption?

[BLOODSWEATSTEEL]

im guessing my stuff is shimano cause my components are shimano? or is that a moronic assumption?

No, it most likely is a correct assumption. Does it say anything on the outside of the crank arms or is there a number M327 or something forged on the inside?

[dfinn]

Common outer BCD's -

130mm - road
135mm - road [Campy]
122 - Stronglight road

110mm 5 bolt - mtb
94mm 5 bolt - mtb compact

146mm XTR M960 4 bolt
112mm XTR M950, M952 4 bolt
104mm XTR [forgot the series,] XT, LX, Bontrager 4 bolt

I'm sure there are more....

interesting. I'm probably running the wrong size bolts. Or is everything pretty standard except for Shimano, who always likes to create their own "standards".

[kidwoo]

interesting. I'm probably running the wrong size bolts. Or is everything pretty standard except for Shimano, who always likes to create their own "standards".

You can't run the wrong size bolts.

BCD bolt center diameter describes the diameter of the circle formed from running a line through the center of the four or five bolts on your spider.

With a four arm it's just the distance between two bolts. Since there is no bolt directly opposite an arm on a five arm, it's more of a hassle.

MOHSHSIHd: depending on how old your cranks are, yours will either be 5 arm compact (94) or 5 arm standard (110). If it was made in the last decade, it's most likely 94.

[kidwoo]

interesting. I'm probably running the wrong size bolts. Or is everything pretty standard except for Shimano, who always likes to create their own "standards".

Oops just realized what you meant.


Yeah you definitely have the WRONG SIZED BOLTS. You have to call shimano directly in yuhpan and ask for the right ones. Remember, for your cranks they only come in TITANIUM. Don't let them try to tell you about standard sizing. You know how they can be about that. MAKE them give the right sized bolts. Read the serial number off your tires and they should be able to tell you what you need.

[MOHSHSIHd]

thanks guys, pretty sure mine are 94 then, the bike is like 7 years old I guess....


tried using a big flathead and a couple came off, but its kinda marring (sp?) the slots, so im gonna go get one of those funky wrenches...

[CS]

big rings are worthless. put a 36 - 38 middle, a bashguard, and be done with it.

[marshalolson]

phish- i have a new raceface chainring for sale at BSR that will fit

[MOHSHSIHd]

phish- i have a new raceface chainring for sale at BSR that will fit

money, ill ask for it when I go in there


hammering it wont work, its basically bent in various places on all sides

[Rontele]

big rings are worthless. put a 36 - 38 middle, a bashguard, and be done with it.

I am realizing that this is very true.

[Choke Slam]

MOHSHSIHd,

Swing by BSR and either get Marshal's ring, or we have a bunch of rings for under $10.

[Darkside]

thanks guys, pretty sure mine are 94 then, the bike is like 7 years old I guess....


tried using a big flathead and a couple came off, but its kinda marring (sp?) the slots, so im gonna go get one of those funky wrenches...

Compact mtn. is only a recent thing, a 7 year old bike is probably a 110BCD, but without knowing what type of crank it is, that's only a guess. Your local shop will be able to help you figure it out and supply you with the ring.

[BLOODSWEATSTEEL]

Compact mtn. is only a recent thing, a 7 year old bike is probably a 110BCD, but without knowing what type of crank it is, that's only a guess. Your local shop will be able to help you figure it out and supply you with the ring.

7 years = 1999. That's not that long ago. Shimano 4-bolts were available in early 97. Compact and microdrive cranks go back to at least 93-94, maybe earlier. Tough to remember exactly, I was just a young wrench then.

[Spats]

big rings are worthless. put a 36 - 38 middle, a bashguard, and be done with it.

The more I ride, the more I agree with you. Big rings are only important if you are racing XC.

[Arty50]

I replaced the big ring (44) on my ride with a 38 and have been super happy. So now I'm running 38-32-22. I have a lot more clearance and it's really helped when doing technical climbing, which I love. But I still can get moving downhill when I need to. The 44 was overkill for any of the riding I do.

[CS]

I replaced the big ring (44) on my ride with a 38 and have been super happy. So now I'm running 38-32-22. I have a lot more clearance and it's really helped when doing technical climbing, which I love. But I still can get moving downhill when I need to. The 44 was overkill for any of the riding I do.

Still too many rings.

Ditch the 32 for the 38 and put a bashguard on and never fear a fallen tree or big rock again.

It's been around 6 years that I haven't run 3 chainrings on a bike. Never missed the 3rd at all. Infact it's more fun. I can try and hop up and on/over rocks and big-ass giant fallen logs and not worry about a worthless, giant calf-slicer getting messed up. One day people will get with it.

[marshalolson]

Ditch the 32 for the 38 and put a bashguard on and never fear a fallen tree or big rock again.

2nd'd. i run a 22-36-bash totally $$$

[Greydon Clark]

What if I keep my big ring but promise to only use it as a bike crampon when climbing logs?