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Gigantic Hawk
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1,776 Posts
Discussion Starter · #1 ·
I'm planning to redo my crankset and gearing this winter. I currently have a set of 175mm E13's, but will probably switch to 170's. I'm looking for a bit more ground clearance, and a little bit more leg comfort (I prefer a shorter crank length.) My question is, should I factor this length reduction into my gearing? The Sheldon Brown gearing calculator shows that those 5mm's can mean a difference of 1 tooth up front. In looking for greater ground clearance, I may go with a smaller cog, and a spiderless crank so that I can run a smaller front ring. Looking at running 28/9 x 16 which is similar to my current setup. Just curious as to others opinions.
 

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The need for singlespeed
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Yep, factor it into your gearing. This way you'll experience the same effort during climbs, and in theory, you can spin faster on the flats.

I'm going to 29/16 spiderless. Losing four teeth and two chain links will allow me to :sleep: more peacefully at night.
 

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Dinner for wolves
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1,567 Posts
I am contemplating a similar change. I have 175s on my SS Canfield and 170s on my fixed Karate Monkey. I don't feel a difference between the crank lengths while climbing. One by one I will replace my cranksets with spiderless 170 set ups. Pedal strikes are common enough here in the rocky East to justify the change. Either bougie SRAM/HBC combos or Middleburn trials set-ups (24:14 - devil horns)
 

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896 Posts
I've got an almost new XTR M-970 cranks listed on ebay right know, they are 172.5 length.

Check them out if you guys want to go shorter from 175 mm

Nothing beats the M-970 for a SS set up, period!

mojo
 

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Low Rep Count
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2,959 Posts
Been running 170's from the get go but with a 32:18. I would love to go to more of a micro drive set up but that will mean replacing my cranks (which I actually love) as well as a new rear wheel (wheels are something I want to get a new set of anyway) since my White's use a freewheel. I haven't seen too many 14t freewheels that are worth much of anything so I would need to get a free hub style rear hub (HOPES!!)

For now and for the sake of money and my marriage, I will stick with what I got! However, I never felt the difference in the 5mm when it came to climbing. I felt a bigger difference when raising/lowering my saddle. However, having longer crank arms will help to provide a longer stretch period in your quads as well as provide for decent leg extension all at the same time. I thought that changing my seat height would help out with that, but lowering my saddle some resulted in my legs just feeling compressed and not really allowed to reach a nice extension (not all the way straight mind you). Sorry, I have been dealing with my quads cramping up lately when my rides exceed 18 miles. Been trying different things and this was one of the things that was suggested.
 

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I too recently switched to 170's. I have about a 29-30" inseam or so. With 175's I felt as though I was forced to pedal in squares. My pedal stroke now seems much smoother "especially" when spinning 120rpm's on the flats. As for climbing I actually feel as though I can stay on top of my gear better. To top it off I used to get some occasional knee pain with the 175's and that now seems to be gone as well.:thumbsup:
 

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Gigantic Hawk
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1,776 Posts
Discussion Starter · #10 ·
My current setup is a 34t Rotor, 175mm E13's, and a 19t trials WI freewheel attached to my rigid Canfield Nimble9. My pedal stroke is much smoother with the Rotor ring, but I'm not sold on it. I also don't like the loss of ground clearance with a bigger ring.

My fixie has 165's, and my old 26er had 165's too. I've never experienced any issues with these shorter cranks (love my fixie setup) so that's what got me thinking about this. I also have a short inseam around 29".

My WI freewheel can be rebuilt into a 16t so that I can keep my 72 points. I am still trying to find out if I'll be able to get a decent chainline running a spiderless crank.

Thanks for the input so far. Nice to see that others have gone this route too.
 

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I too recently switched to 170's. I have about a 29-30" inseam or so. With 175's I felt as though I was forced to pedal in squares. My pedal stroke now seems much smoother "especially" when spinning 120rpm's on the flats. As for climbing I actually feel as though I can stay on top of my gear better. To top it off I used to get some occasional knee pain with the 175's and that now seems to be gone as well.:thumbsup:
I have a 29-30'' inseam as well.You inspired me to put my take off my 175mm cranks and try the 170mm cranks on my 29er ss! I also threw on the bash guard!

Now i cant wait to take all of the components off and put on my new Tomac flint ss!!! In mid November.
 

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Gigantic Hawk
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1,776 Posts
Discussion Starter · #14 ·
I have a 29-30'' inseam as well.You inspired me to put my take off my 175mm cranks and try the 170mm cranks on my 29er ss! I also threw on the bash guard!

Now i cant wait to take all of the components off and put on my new Tomac flint ss!!! In mid November.
Looking forward to hearing how this turns out for you.
 

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.......
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I just went 165mm (from 172.5) on my fixed roadie two weeks ago. I like the spinability. I didn't notice any loss of leverage on climbs either. I'd like to try 170's on my MTB.
 

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Jam Econo
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4,213 Posts
I had always run 170s until a bad thing happened.

I decided to try 175s to see about this add leverage everyone was talking about. At first it felt like I was riding a bike too big for me but I quickly adapted. Then another bad thing happened

so I slapped some compact road cranks in the 170 length and I liked how they felt a little "spinnier".
I never had to adjust my gearing between crank lengths.
 

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hispanic mechanic
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2,701 Posts
I've used 170mm cranks for about 8 years now. I'm about 5'11" with a 33" inseam, and have run the gamut of crank lengths- 165mm for DH and on the track, 172.5 on the road, 180 when I started SS, 185 for BMX...
When I turned my Karate Monkey fixed, I found myself having a hard time spinning those 180s on the long SoCal downhills, so I switched to 170, and have not looked back. Wes Williams was big on shorter cranks for his "28"" bikes way back when, and it feels good to me. I really do feel like I can stay on top of the gearing on climbs better with shorter cranks.
The only issue I have is that the Ritchey WCS cranks I have use the same length arms with different drilling for both 175 and 170 so I get no clearance advantage.
Oh and currently I have a 32x18, but am considering gearing down a touch. I like your idea of going spiderless and a 29t, but I'm concerned about wear- cost and a availability of replacement rings.

Los
 

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sslos;8519981 The only issue I have is that the Ritchey WCS cranks I have use the same length arms with different drilling for both 175 and 170 so I get no clearance advantage. Oh and currently I have a 32x18 said:
I'm considering moving to a shorter crank, but right now I'm running an XT m739 with an HBC 30t spiderless that's working great. As long as you don't mind a little wait the HBC rings are available.

I think you would still get clearance benefit with your WCS cranks. It seems like pedal strikes are more common than crank hits, and the cornering/toe clearance has to do with the pedal location, not the actual crank length. I guess if you are hitting your cranks a lot it might not matter much.
 

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hispanic mechanic
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2,701 Posts
I'm considering moving to a shorter crank, but right now I'm running an XT m739 with an HBC 30t spiderless that's working great. As long as you don't mind a little wait the HBC rings are available.

I think you would still get clearance benefit with your WCS cranks. It seems like pedal strikes are more common than crank hits, and the cornering/toe clearance has to do with the pedal location, not the actual crank length. I guess if you are hitting your cranks a lot it might not matter much.
You'd be surprised how much more I hit the crankarm on these compared to my White Industry cranks. Unfortunately, the massively long BB required to clear the chainstays introduces noticeable flex- first time I've had flex in a BB/crank that I've been able to discern.
Had it not been for that, I'd happily stay with the WI and go 30x17.

Los
 
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