Cranky thinking!- Mtbr.com
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  1. #1
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    Cranky thinking!

    HEY good people! I am gonna get me a new crankset. I've been riding 175mm long arms for years, but wondered if I might be better off with 170's for length? I am 5'-9" in height and have a 30" inseam. what do you think is the pros/cons when it comes to torque, spinning, ground clearance etc.?
    anyone riding 170's now? Would the 5mm even be a noticeable difference? Any recommendo's on a good crankset for trail, all mountain type riding, would also be welcomed. Thanx huge for any thoughts you can give.
    RAM speed: UP, UP, and away....!

  2. #2
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    Lew,
    If it were me, I would go to a Specialized body geometry shop or whoever else offers that service and get your bike "fit kit" there will be a proper length crank set for you. Don't guess at it.
    Steve
    Drinkin the S-Works Kool-aid

  3. #3
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    I went from 175 XT to a 170 SLX crank about 1 1/2 seasons ago.

    I honestly don't remember if there was much of a difference, but Im fully used to my setup now and it didn't take that long. I have a 36t single ring up front, so I need to spin a little more than big ringers anyways. I don't know if I get less crank strikes b/c of 170mm or I just got used to the bike.

    You will have to raise your seat for the same leg extension...it made me feel a little less stable with the higher centre of gravity, but again its not that big a deal.

    Try it out, its only 5mm.

  4. #4
    Huffy Rider
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    I am 5'4" with a 31.5" inseam and hated riding with 175's. I went to 170's and then when that bike got stolen, I built my new one with 167.5's. My husband is 5'11" and he went from 175's to 170's. We both have nothing but positive things to say about the change. The ground clearance thing was HUGE for both of us as we mostly ride in Sedona. We are both 20yr+ roadies so we like to spin, but there is plenty of torque available on an upshift to get you up and over obstacles.

    So yes, I would say without any hesitation based on my personal experience to go shorter. I really don't understand why manufactures insist on equipping every bike from S-XL in 175's. I won't even demo new bikes anymore if they have 175's, can't stand it. It takes away from the demo experience enough that I won't even give their bike a ride.

    5mm is a big difference and you will notice it, in a good way. I went 7.5 which is huge, I wouldn't change a thing, best thing I did to my bike. Think about it, your circle is going to be 10mm shorter all the way around. It has also taken away some slight knee pain I had with the longer ones, and I don't hit my knees on the bars. I also don't feel like my knees are going to rub on my armpits. (obviously cuz I ride a small and they never should have had 175's to begin with) The amount of bend in the top part of your knees will decrease not making you feel so folded up. I am having a hard time explaining with words, but hope you get the idea.

    As far as cranksets, I can only recommend what we both use. They are DaVinci's (as is tandems) and they use a square taper BB. We love them, cheap, light and versatile. Got questions? Ask.

    Brenda

    PS no cons

  5. #5
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    Great info from all thanks. I have felt like the 175's are a bit much, but never enough to do much about it. Now I have a new frame with more travel, and a lower bb. I need to go to an external type of crankset to accommodate the frame, and so this is a good time to change the arm length. My main concern was whether the climbs would get me if I lost some leverage. But it sounds like Brenda finds that she uses less energy in the long run because of being able to spin smaller circles. sort of like comparing regular squats to deep squats when lifting weights. is that what you mean motochic?
    RAM speed: UP, UP, and away....!

  6. #6
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    Ya, I guess that is a good way to put it. The smaller circles thing is the key, the benefit.

    Good luck!

  7. #7
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    It is so true that the small and med frame bikes should not have the 175's for most short inseam people .

    Small for sure should not have them.


    For me the 175's are way small and to tight of a circle .....( I have a 41" inseam and the XL bike is to small).

    On my road bikes I was making a 188 to 195 throw for me and really loving it , on my mountain bike since I ride the nasty hack and slam up stupid ledges and boulders I have to stay with the little 175's .......they are hard for me to turn smoothly but they do clear the ground with my high BB

  8. #8
    No Clue Crew
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    Quote Originally Posted by kelstr View Post
    For me the 175's are way small and to tight of a circle .....( I have a 41" inseam and the XL bike is to small).
    Jesus Christ, how tall are you, Kelly? I'm 6'2" with a 34" inseam and you don't look too much taller than me although I don't think I've ever seen you off the bike...

  9. #9
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    Quote Originally Posted by big0mike View Post
    Jesus Christ, how tall are you, Kelly? I'm 6'2" with a 34" inseam and you don't look too much taller than me although I don't think I've ever seen you off the bike...
    Im only 6'4" but I have really long legs , and then to make matters worse my arm reach is 3" longer than my height ( generally your height is equal to your arms from end to end ), so I am really screwed up when it comes to bike fit .

    Most XL bikes are still small and the bars are way to low , My XL is a really big XL and I was able to almost get the bars and ft end up correctly , and If I run the seat 2" low I kind sorta feel close to comfortable for AM riding.

    A 190 crank would be the ticket but with only a 14.25" BB height I will not be able to get away with it for AM AZ type riding.

  10. #10
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    I got a pivot Firebird off ebay which came with 170 for over 10 years before this I rode 175. There is a noticeable difference when going up hills=less power.other than that less pedal strikes and I have gotten usewd to it in three months.I am 5'10

  11. #11
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    You all got me thinking now. I just picked up a HIFI Deluxe and this is my first "nicely" and fully suspended bike. On the first test ride today I slammed the ground or rocks four times. Two were so hard it made my hip sore! I stand at 5' 11'' with a 32 inseam, and of course I was looking at parts to save some weight on this thing. I am going to need rings soon, maybe I will keep a look out for a deal on rings and 170's.
    Vassago Cycles, Shadetree Bikes, Flat Tire Bikes, Galfer Brakes USA

  12. #12
    My other ride is your mom
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    I switched from a 175 to a 170 and did notice off the bat a bit less leverage, but I've since forgotten all of that. My ITBS pain went away or was greatly reduced....so for me it was a great change. As others have said, don't forget to adjust your seat height accordingly.




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