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Discussion Starter #1
I'm in the process of converting my old steel hardtail Trek 930. The cranks (shimano STX) have this compact spider (5 arm) with a 94/58mm BCD. My problem is twofold:

How do I set it up for One chainring up front? The way it is configured is that the granny is the only ring attatched to the crankarm. The middle bolts to the granny and the outer to the middle. Is there any adapter I could use to mount just a middle ring or posssibly a big ring?

Do they even make a bigger chainring (42T and up) to bolt to a 58mm?

thanks for any help in advance
 

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disco said:
I'm in the process of converting my old steel hardtail Trek 930. The cranks (shimano STX) have this compact spider (5 arm) with a 94/58mm BCD. My problem is twofold:

How do I set it up for One chainring up front? The way it is configured is that the granny is the only ring attatched to the crankarm. The middle bolts to the granny and the outer to the middle. Is there any adapter I could use to mount just a middle ring or posssibly a big ring?

Do they even make a bigger chainring (42T and up) to bolt to a 58mm?

thanks for any help in advance
I am not familiar with that crank, but chain rings are not always so cheap. It could be an entry-level crank sold to meet a low price point vs. have broad compatibility.

You might want to consider a moderately priced single speed crank that's ready to go and even in 180mm which is nice for single speed use. I think a 180 mm Stylo and ISIS bb I got were around $135.

You can also search classifieds and eBay for take off 175 mm Truvativ Stylo ss cranks. You'll also see used low cost cranks where you can easily add fresh 36t 5 bolt and 18t in back for not a lot of money.

FWIW: My larger diameter 36 18 setup is quieter than my 32 16 setup.

Don't be afraid of a lot of older stuff if you're on a budget. Don't forget that people used solid bottom brackets and 5 bolt cranks for a long time.

Good luck.
 

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I used that crank of a trash find 930 to set up my first single speed (the 930 frame became my geared MTB). I mounted the middle ring along with the granny. You may have chainstay clearance issues if you find a 42 tooth that will bolt directly to the crank. I do not know if they make one, but there are some custom fabricators that could probably cook up something for you depending on how much cash you want to spend. For me, there was no real disadvantage to leaving the small ring on there with the middle.
 

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The man who fell to earth
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I have an old Trek 950, and it had the STX crank you mention. I gave the cranks away years ago, so I don't remember how it was configured. But if it has a standard 94 mm outer (non granny ring) 5 bolt pattern, then I would think you should be able to simply bolt a chainring on without a whole lotta fuss. You will need smaller chainring bolts to secure the chainring by itself, or use washers (hard to find) or use a bashgard with the standard long bolts (used to secure the middle and big ring instead of just one).

Take a look at this ring ($17 @ aebike.com):



Does this look like it will work? They make them in many differing sizes too, so if you want larger just search the catalog for bigger (or smaller).

And here are the bolts you'll need:



Here are the links too:

https://aebike.com/site/page.cfm?PageID=30&SKU=CR4376

https://aebike.com/site/page.cfm?PageID=30&SKU=CR0010

Good luck



disco said:
I'm in the process of converting my old steel hardtail Trek 930. The cranks (shimano STX) have this compact spider (5 arm) with a 94/58mm BCD. My problem is twofold: How do I set it up for One chainring up front? The way it is configured is that the granny is the only ring attatched to the crankarm. The middle bolts to the granny and the outer to the middle. Is there any adapter I could use to mount just a middle ring or posssibly a big ring? Do they even make a bigger chainring (42T and up) to bolt to a 58mm? thanks for any help in advance
 

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Discussion Starter #5
This project may have to go on the backburner for a while. Was trying to do this on the cheap for kicks but with so many other things going on for me right now (house, baby) this is low priority. Ideally, I wanted a true SS to ride on the street to train with (why I wanted a bigger CW). Added a rigid fork and v-brakes to the front, and nixed the front der. Was hoping to have a clean looking bike with just one ring up front and a magic ratio.

For now, I'll just ride it as a seven speed (7spd cassete in back) or maybe use a tensioner and trim it down to 3 speeds (manual - haha)

At the time, the STX group fell between Alivio and LX for Shimano.

thanks for your help fellas
 

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Discussion Starter #6
Ziggy-Stardust said:
I have an old Trek 950, and it had the STX crank you mention. I gave the cranks away years ago, so I don't remember how it was configured. But if it has a standard 94 mm outer (non granny ring) 5 bolt pattern, then I would think you should be able to simply bolt a chainring on without a whole lotta fuss. Good luck
thanks Ziggy,

that's just it, it seems the only ring that actually connects to the crank is the granny, which is something like 58mm. The other two are bridged off of it. What a POS!
 

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The man who fell to earth
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Wow, so it only has a small 58mm bolt circle huh? They might make larger chainrings that would bolt to that size, but I haven't seen them. I dunno, all I can think of is possibly adapting a BMX type chainwheel similar to this:



Not sure if it would work though. They also make solid (undrilled) BMX chainwheels that I suppose you could drill the 5 bolt pattern into and enlarge the center hole if need be. But that's a hassle, probably easier just to get an old standard 94mm or 104mm 4 or 5 bolt crank. You can usually pick them up really cheap on ebay or ask your LBS if they have any old stuff laying around.

disco said:
thanks Ziggy, that's just it, it seems the only ring that actually connects to the crank is the granny, which is something like 58mm. The other two are bridged off of it. What a POS!
 

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The man who fell to earth
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Actually I just spoke with the guy I gave my cranks to. Here's what I had (STX-RC circa '94 vintage):



If you have the same crankset, I'm 95% sure they have the 94mm BCD (in addition to the smaller BCD for the granny). The 5 bolt, 94mm BCD chainring shown above should bolt right up to these cranks. Don't want to steer you wrong, but I'm pretty darned sure they should work.

Good luck


disco said:
thanks Ziggy, that's just it, it seems the only ring that actually connects to the crank is the granny, which is something like 58mm. The other two are bridged off of it. What a POS!
 

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Discussion Starter #9
Ziggy-Stardust said:
Actually I just spoke with the guy I gave my cranks to. Here's what I had (STX-RC circa '94 vintage):



If you have the same crankset, I'm 95% sure they have the 94mm BCD (in addition to the smaller BCD for the granny). The 5 bolt, 94mm BCD chainring shown above should bolt right up to these cranks. Don't want to steer you wrong, but I'm pretty darned sure they should work.

Good luck
That's them. I hope you are right. I haven't actually taken these apart yet, but from what I can tell, while it appears the outer chainring will attach to the spider - it doesn't. Those bolts are attatched to the middle ring which is in turn attatched to the granny. I don't know, maybe I'm losing my mind..........I'm definitely going to dissect these tonight and report back though - thanks again!
 

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Sweep the leg!
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If I remember correctly Shimano riveted those granny gears onto the crank spyder. Drilling or filing the rivets off would be the correct remedy.
 

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Caffeine Powered said:
If I remember correctly Shimano riveted those granny gears onto the crank spyder. Drilling or filing the rivets off would be the correct remedy.

Not on my stx crank. It is like the one pictured, but with a lot more dirt.
 

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Discussion Starter #12
disco said:
That's them. I hope you are right. I haven't actually taken these apart yet, but from what I can tell, while it appears the outer chainring will attach to the spider - it doesn't. Those bolts are attatched to the middle ring which is in turn attatched to the granny. I don't know, maybe I'm losing my mind..........I'm definitely going to dissect these tonight and report back though - thanks again!
confirmed that these are all attatched to the inner BCD, I am officially in the market for some cheap cranks......
 

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i have those cranks...

a 94 bcm 5 bolt ring will attach to your middle or outer ring position i believe! they work the same way any thoer set of crnaks i have works middle and outer ring bolt to the spider and the granny bolts onto the crank itself.

what ziggy showed in his first post should work just dandy!

i still have the cranks around cause they are fitted wit a 20 tooth granny ring (just in case ;) )
 

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Discussion Starter #14
max-a-mill said:
i have those cranks...

a 94 bcm 5 bolt ring will attach to your middle or outer ring position i believe! they work the same way any thoer set of crnaks i have works middle and outer ring bolt to the spider and the granny bolts onto the crank itself.

what ziggy showed in his first post should work just dandy!

i still have the cranks around cause they are fitted wit a 20 tooth granny ring (just in case ;) )
trust me - I took them apart and the BIG and MIDDLE CHAINRINGS DO NOT ATTATCH TO THE SPIDER. Big attatches to middle attatches to granny, it's jacked - I'll post pics to clarify.....they are Shimano STX but older than teh ones pictured above


can I mix and match crank arms? will this work (so I can bolt a single big chainring) with my STX crankarm on the left without feeling all different and weird?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=56193&item=7154708419&rd=1&ssPageName=WDVW

They are both 175mm, anyone else done this?
 

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I am running the STX on one side and a deore on the other. NO problems. The only problem I have found when doing this is combining a bontrager crank and a deore crank. The cranks were not parallel when they were mounted on the tapers.
 

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Sofa King We Todd Did
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Disco, how much do you really want to spend on a workable crankset? With all this mixing and matching, you might well be better off scoring a new crankset rather than trying to retrofit old and probably worn parts.

For a mere $22 you can get a set of 5-bolt 175mm square taper crank arms:
http://aebike.com/site/page.cfm?PageID=30&SKU=CR7918

For another $15, you can get a big 46T chainring upfront:
http://aebike.com/site/page.cfm?PageID=30&SKU=CR7296

So for a relatively inexpensive $37, you got yourself a tough-as-nails new crankset that'll probably last you donkey's years. And if your Trek uses the same geometry as my 1991 Trek 950, then you'll be happy to know that I found a magic gear ratio well suited for road-going use: 46/18.

What do you think?
 

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Discussion Starter #17
Greenfix said:
The only problem I have found when doing this is combining a bontrager crank and a deore crank. The cranks were not parallel when they were mounted on the tapers.
doh!

thanks, that's good to know! is your STX crankarm the drive side?
 

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Discussion Starter #18 (Edited)
SpinWheelz said:
Disco, how much do you really want to spend on a workable crankset? With all this mixing and matching, you might well be better off scoring a new crankset rather than trying to retrofit old and probably worn parts.

For a mere $22 you can get a set of 5-bolt 175mm square taper crank arms:
http://aebike.com/site/page.cfm?PageID=30&SKU=CR7918

For another $15, you can get a big 46T chainring upfront:
http://aebike.com/site/page.cfm?PageID=30&SKU=CR7296

So for a relatively inexpensive $37, you got yourself a tough-as-nails new crankset that'll probably last you donkey's years. And if your Trek uses the same geometry as my 1991 Trek 950, then you'll be happy to know that I found a magic gear ratio well suited for road-going use: 46/18.

What do you think?

great idea homie, those look bullet proof

what about these for $45 if I strip the other two rings off ???

http://aebike.com/site/page.cfm?PageID=30&SKU=CR1033
 

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Sofa King We Todd Did
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Those come well rated by Matt Chester, I believe. But because the chainrings have ramps and pins and are designed for shifting, often users will replace them with an unramped chainring. That being said, I use the original crankset that came with my Trek 950. 5-bolt Deore LX cranks arms that weigh a ton, mated to the large 46T chainring that came with it, ramps, pins and everything. They work like great.

 

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Discussion Starter #20
SpinWheelz said:
Those come well rated by Matt Chester, I believe. But because the chainrings have ramps and pins and are designed for shifting, often users will replace them with an unramped chainring. That being said, I use the original crankset that came with my Trek 950. 5-bolt Deore LX cranks arms that weigh a ton, mated to the large 46T chainring that came with it, ramps, pins and everything. They work like great.

]

done and done........ordered and on their way......oh man I am in trouble.... :D
 
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