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I am considering building up another bike for beach/sand riding only on 100mm rims / BFL & have been considering a few build options, so....I was looking through my collection of old bike parts the other day to see what I have for my next fat build & I found an old set of 1995 shimano STX RC crank arms.

I have just realised that these are similar to the Surly Mr Whirly, 5 arm 58mm BCD:thumbsup:
The granny & middle ring were bolted to the crank & the big ring was bolted to the middle ring using spacers....



So, I am thinking that I could build a bike up with a PW bottom bracket, STX-RC cranks & a Mr Whirly offset ring would work fine?

Unsure if I'm going to build this as a 1x9 (12-36) or IGH, so I'm confused about front ring size for beach crawling.... does a 24t sound ok to you guys?

Advice welcome:thumbsup:
 

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Well, any square taper can be built with a wider Phil Wood BB to get the clearance. What's helpful is that by bolting to the crank you can keep the Q factor lower.

The MWOD cranks aren't too bad for cost though. About $240-$250. Phil BB is what, $120? MWOD rings are like $70. So you're at $190. Not too much more just to have the whole cranks.
 

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Harmonius Wrench
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I've got a set of those cranks in the basement. (Lord only knows why. :D)

The thing is, the MWOD works since the middle ring sits where the outer ring would normally in the chain line. Granny sits where the middle ring would. That STX crank doesn't do that. You're not gaining anything by using that design. (It also is heavy as heck to boot)

Go with the MWOD, or get an Origin 8 Sub Compact double that can be switched over to a 22 X 32 and does move the rings in the chain line over a bit. (Uses an ISIS BB by the way) Milltown Cycles has sold a few Muk builds using this crank with BFL's on 82mm RD's and with a couple cogs removed out back, there is plenty of clearance.
 

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The thing is, the MWOD works since the middle ring sits where the outer ring would normally in the chain line. Granny sits where the middle ring would. That STX crank doesn't do that.
It will if you remove the middle ring, because the middle ring acts as a spacer to locate the granny ring in its "standard" position. If the middle ring is removed, the granny ring will shift to somewhere close to middle ring position. I can't say if there would be chain/spider clearance issues, though, since I don't have one in my hands.
Assuming that the MWOD ring set would clear the STX spider casting (probably), adding the MWOD rings would give you basically the same setup as the complete MWOD crank.
However, with the price of just the Phil BB being nearly the same as the complete MWOD crank, I don't see the point- unless you wanted to do a super-el-cheapo drivetrain with a single front ring and a $30 Choppers US bottom bracket.
 

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Harmonius Wrench
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It will if you remove the middle ring, because the middle ring acts as a spacer to locate the granny ring in its "standard" position. If the middle ring is removed, the granny ring will shift to somewhere close to middle ring position.
I understand your point, but you will only gain about a millimeter or two at best, (the width of the middle chain ring, which is sandwiched between the granny and the spider on an STX crank), and that still won't put the granny where the middle ring would normally be. (The middle ring on an STX is stamped offset, see the diagram)

So, if the MWOD granny is flat, (I assume it would be), there would be little to gain by using an STX crank. That's assuming, as you say, that the middle ring would clear the dummy ears of an STX without major grindage.
 

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I understand your point, but you will only gain about a millimeter or two at best, (the width of the middle chain ring, which is sandwiched between the granny and the spider on an STX crank), and that still won't put the granny where the middle ring would normally be. (The middle ring on an STX is stamped offset, see the diagram)

So, if the MWOD granny is flat, (I assume it would be), there would be little to gain by using an STX crank. That's assuming, as you say, that the middle ring would clear the dummy ears of an STX without major grindage.
If I remember correctly- I had a pair of these cranks a while ago, but gave them away- the granny ring is also stamped offset, in the opposite direction (towards the seat tube). So, putting a flat ring on there (MWOD, or just a single ring) will gain more than just the thickness of the middle ring ears. You are right that it won't shift all the way over to the middle ring position, due to the offset of the stock middle ring.
I don't think there's really anything to gain by using the STX crank, unless you already have one and don't want to spend any money.
 

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Harmonius Wrench
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If I remember correctly- I had a pair of these cranks a while ago, but gave them away- the granny ring is also stamped offset, in the opposite direction (towards the seat tube). So, putting a flat ring on there (MWOD, or just a single ring) will gain more than just the thickness of the middle ring ears. You are right that it won't shift all the way over to the middle ring position, due to the offset of the stock middle ring.
I don't think there's really anything to gain by using the STX crank, unless you already have one and don't want to spend any money.
I've got one, as I stated earlier. The granny is not offset. Again, you can see this on the diagram posted above.
 

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I had one of these. My foggy memory is that it came new with a stamped/pressed offset granny, and at some point over a decade ago, I switched it to a flat granny with thin spacers to make it clear the middle ring.

Could the spider be drilled through, flats cut on the back, and some serious offset gained?
 

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Harmonius Wrench
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I had one of these. My foggy memory is that it came new with a stamped/pressed offset granny, and at some point over a decade ago, I switched it to a flat granny with thin spacers to make it clear the middle ring.

Could the spider be drilled through, flats cut on the back, and some serious offset gained?
I could go down in the basement, grab mine that I've examined over the past few days, and post pics, but trust me.....it ain't worth messin' with an STX crank. ;)

By the time you find out it won't work you could order one that would and be done with it and riding.
 

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Wouldn't the Phil/STX(any 58mm crank) be lighter than Whirlys? It wouldn't be much cheaper(ti would be more), but there's potential for weight savings. The Whirlys hold to true to Surlys durable philosophy, so of course are as heavy as some DH cranks.
 

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Harmonius Wrench
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Wouldn't the Phil/STX(any 58mm crank) be lighter than Whirlys? It wouldn't be much cheaper(ti would be more), but there's potential for weight savings. The Whirlys hold to true to Surlys durable philosophy, so of course are as heavy as some DH cranks.
STX rings are stamped steel. Not very light. Any other 94/58BCD crank, (Old Sugino comes to mind, as I have a couple here) would be lighter than Whirlys with aluminum rings installed.

In fact, I have a 20/30T ring set and the aforementioned crank sets. Now I just need a phil BB......
 

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I have to agree with GT on everthing; I have this crankset as well and was planning to use it as a low-geared SS (not on a fatbike) and can verify that this crank is NOT like the Surly MWOD at all.

@GT: too bad you didn't get to swipe the Phil BB at TripleD, huh?
 
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