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I am currently running an old m760 crankset XT with a 32t on my beat up steel 29er. Lately I've been toying with the idea off getting a smaller front ring to increase my obstacle clearance for rolling logs or high-sided boulders/rocks. Then gear the rear cog appropriately, ie. 32-22=29-20. The problem of course is that the BCD of the XT crankset is too large, so a smaller ring than 32 would not fit, at least not in the middle ring position of the triple ring crankset.

One need I have is a super strong crankset, preferrably with an outboard bearing design, as I am a clyde and really pound the bottom bracket. I've been told by shops that the ENO would not hold up for me. Do I need to go custom? If so, who do you recommend?

Lastly, to see if this is worthwhile, how many teeth would I need to drop up front to gain significant clearance, like 1/2 in? Does anyone know of a calculator where you can input the BCD and teeth and get a radius back?

Thanks!
 

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if your a big guy and are worried about breaking stuff, look into Profile BMX cranks with BMX sproket, they are hollow tubular Cromoly cranks. the spindle is steel and pretty heafty, but if you have the cash they make a Ti spindle (although it may have a weight limit)

for rings you can find anything form a 24-46t in plenty of options as well as colors if your into bling

forums.mtbr.com/ showthread.php?t=465969
 

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local trails rider
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Get a Shimano SLX with a 32T ring, and use a bash ring.
(or Saint, if you want a really Really REALLY tough crank)
 

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perttime said:
Get a Shimano SLX with a 32T ring, and use a bash ring.
I guess that we'll disagree about the need for a bashring (and that's fine, It's what people do:D ) but personally I've found them more a hindrance than a help. If your'e always rolling rock steps then maybe, but I find that the space between the bash and the chainring just serves to hold a lot of debris (grass, small twigs, heather etc) which starts to force the chain to run further out on the chainring.
I had this problem running a 2x9 setup, but sometimes you were on the granny ring and needed something to protect the other chainring.
I reckon that the chain does a pretty good job of protecting the chainring on a SS though.

Prob.depends where you ride as much as anything...
 

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local trails rider
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Andy R said:
I guess that we'll disagree about the need for a bashring (and that's fine, It's what people do:D ) but personally I've found them more a hindrance than a help. If your'e always rolling rock steps then maybe, but I find that the space between the bash and the chainring just serves to hold a lot of debris (grass, small twigs, heather etc) which starts to force the chain to run further out on the chainring.....
We can agree to disagree...:p

I originally went for a bash for a couple of reasons:
- extra protection, as I'd damaged a big ring and bent my derailer hanger before going SS
- standard length chainring bolts work without any fudging

Later, I discovered one more reason:
- some have managed to break four bolt chainrings and spiders in SS use. I figure a bash will reinforce the system like a big ring does.

Debris does tend to stick there, and the bash ring makes it harder to get out.
 

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If you're a clyde and running a SS I heartily recommend going with BMX cranks. I agree that Profiles rock but you can get some with a Euro BB for around a $100. Once you try them you won't go back.
 

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Try some Middleburns. The RS7 is super-tough, warranted for trials and DH. They do a nifty SS ring called the Uno, but it only goes down to 32t.



They also do a double set-up (the Duo) which has a 27t or 29t inner, which you can run on it's own similar to an Uno.

Then just get a nice square taper BB (Phil Wood, White, SKF), or just use Shimano UN54, they're cheap enough to replace every few months, but tough enough that you shouldn't need it.

For the record, I don't reckon outboard BB bearings are any tougher than decent square taper ones.
 

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Well, a 32t ring is ~4.5" in diameter. A 29t ring would be ~4.3". So you'll gain 3/32" clearance by changing out the crankset and ring to a 29t. Not worth it. You'd have to go to a trials setup to get the kind of clearance you want.

Perhaps spend your money on a frame with a higher BB.
 

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Had some experience with the Middleburns. Not very stiff - in fact quite flexy (I'm only 160#). Outboard bearings do make a big difference, especially for a clydesdale-type fellow. I'd not recommend square-taper.

At one point I wanted to experiment with more clearance up front, so I ran a 24-15 on my 29er. That setup did give me noticeably more clearance, but it went through chains and rings VERY quickly (less surface area for the same amount of force). Unless this sounds like an agreeable trade-off to you, I'd agree with others above - going from a 32 to a 31, 30, or even 29 isn't going to be that big of a deal, certainly not enough to warrant changing cranks and such. Good luck!
 
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