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  1. #1
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    light crank, lowest q factor?

    What crank and BB will give me the tightest q factor. Q factor is important, followed by price, followed by lightness. Thanks.

  2. #2
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    road BB...

    Quote Originally Posted by dmrun148
    What crank and BB will give me the tightest q factor. Q factor is important, followed by price, followed by lightness. Thanks.
    whatever crank you may choose...a road BB will get you a narrower Q-factor.
    on square BBs the road lenght is 103mm vs 107mm of MTBs
    octalink XTR has 112.5mm vs DA that has 109mm and the same spline
    ISIS road has 108mm vs 112mm of MTBs

    next in line is the pedal width which varies big time. you want to stay away from Eggbeaters as those are ca. 10mm wider overall than other pedals. narrowest pedals usually are Ritcheys. narrower by a couple of mm! you also want to adjust the cleats on your shoes all the way to the outside of the adjustement range. that's what Thomas Frischknecht does and also will bring your feet inwards by a couple of mm per side.

    as for cranks you will also have to check Ritchey cranks which usually are the narrowest on the market.
    if Q-factor is that important definitely stay away from all the integrated cranks as these are all wider that the regular counterparts!

    as an example:
    -my Ritchey WCS octalink crank with XT octalink BB measures 165mm.weight of crank+BB = 935g
    -on my MTB i have a FRM Ti BB (with Ritchey road 103mm square axle) and Storck powerarms...Q-factor =165mm at an overall weight of just 560g
    -integrated 04 XT had 180mm / 910g

    anyway - each part of the whole combination of BB,crank, pedal and cleat has a couple of mm potential! all together this resulted in almost 30mm (!) narrower Q-factor on my winterbike when i switched from XT integrated back to Ritchey cranks and other pedals etc...a BIG IMPROVEMENT!

    i would guess that a old Ritchey WCS SQUARE crank on a 103mm axle would be narrowest. i'd say 155-160mm should be doable that way. next in line should be the ISIS-version on a 108mm road BB.
    Last edited by nino; 01-27-2005 at 04:22 AM.

  3. #3
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    Have to be carefull though....

    Too narrow a spindle and crank setup you may run into problems with chainsuck. Also I had a problem once that I couldn't get my E-Type front derailleur to shift to the granny gear.

  4. #4
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    its for singlespeed

  5. #5
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    [QUOTE=nino]whatever crank you may choose...a road BB will get you a narrower Q-factor
    [...] anyway - each part of the whole combination of BB,crank, pedal and cleat has a couple of mm potential! all together this resulted in almost 30mm (!) narrower Q-factor on my winterbike when i switched from XT integrated back to Ritchey cranks and other pedals etc...a BIG IMPROVEMENT! [...]
    QUOTE]

    What you say is true for most people, but some pedal with their heels pointed inward, which means they need a short BB axle lenght and a relatively long pedal axle lenght. For example, I can only use an Eggbeater (or a Shimano with the cleat pushed all the way out) with a Hollowtech II XTR or and old Ritchey Logic crank, though with low profile cranks like the TruVativ Stylo, I can set the Shimano cleat all the way inward...

    -b

  6. #6
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    Quote Originally Posted by Mr. Scary
    Glad I don't have your knees they must ache!
    You should try some Specialized shoes with the Varus wedge technology, it may help straighten your pedaling stance. Sounds like you are rolling your ankles.
    Never had any knee problems, and I pedal with my knees inward as well. My inward ankle/knee "style" is nothing compared to what I see at races from guys in front of me, or even some pros. It's simply something that you are born with. Zatopek, the first man to run 20 kms in one hour had such a funny running style that many thought he had some serious problems...

    -b

  7. #7
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    I'm duck-footed as well

    My heels hit my cranks no matter what I do. I don't run road pedals on my road bike because the spilndles are too short and I smack my feet on the cranks and stays- I use eggbeaters instead. In my mtb, I rubbed the label off my old XT cranks in under 6 months- not muddy riding either. Last year in one muddy race I rubbed groves into the sides of the crank.

    Moral of my story anyway is that while a low crank Q-factor might be ideal (provided you can get your chainline right- shouldn't be a problem on a single), low pedal spindle length could cause problems for some people.
    A hardtail is forever

  8. #8
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    8mm per side...

    Quote Originally Posted by Hardtailforever
    My heels hit my cranks no matter what I do. I don't run road pedals on my road bike because the spilndles are too short and I smack my feet on the cranks and stays- I use eggbeaters instead. In my mtb, I rubbed the label off my old XT cranks in under 6 months- not muddy riding either. Last year in one muddy race I rubbed groves into the sides of the crank.

    Moral of my story anyway is that while a low crank Q-factor might be ideal (provided you can get your chainline right- shouldn't be a problem on a single), low pedal spindle length could cause problems for some people.
    i on the other hand have 8mm of space between my feet and the crankarms when clipped in in the Eggbeaters...
    that's much mm too wide a Q-factor...

    not all have orthopedic problems!

  9. #9
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    Ritchey logic cranks

    Quote Originally Posted by dmrun148
    What crank and BB will give me the tightest q factor. Q factor is important, followed by price, followed by lightness. Thanks.
    I have two single speed set-ups using Ritchey logic cranks, requiring older, square taper bottom brackets (I use Phil Wood). A Ritchey logic compact with a 32 tooth ring weighs 540 grams and has a q-factor of 154mm (outside to outside of crank arm) when mounted on a 108 mm spindle. As Nino notes, your model of pedal will also impact q-factor.

    I also have an even older standard Ritchey logic crank on a phil wood bottom bracket (I don't know the spindle length however) that has a 145 mm q-factor -- it just clears the chainstays of a Bridgestone MB-1 frame. I know that the "pitch" of the crank arms are different for the two Ritchey cranks such that the older standard Ritchey logic crank won't clear the chainstays of my main ride using the 108 mm spindle, whereas the "newer" Ritchey Logic compact crank does work. There is no difference in chainline between the two cranks.

  10. #10
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    Quote Originally Posted by nino
    i on the other hand have 8mm of space between my feet and the crankarms when clipped in in the Eggbeaters...
    that's much mm too wide a Q-factor...

    not all have orthopedic problems!
    Well at least I don't have a problem with my road bike, even when running 2004 Dura Ace cranks which are not really low profile at all. I like low Q-factor and narrow chainline, but for me there is a limit: I need a few mms longer pedal axle. Actually I didn't understand in your previous posts how you managed to run a minimum Q-factor setup + very short pedal axle. You might have opposite othopedical problems... and very small feet. Anyway: who's perfect...

    -b

  11. #11
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    2 different things...

    Quote Originally Posted by macsi
    Well at least I don't have a problem with my road bike, even when running 2004 Dura Ace cranks which are not really low profile at all. I like low Q-factor and narrow chainline, but for me there is a limit: I need a few mms longer pedal axle. Actually I didn't understand in your previous posts how you managed to run a minimum Q-factor setup + very short pedal axle. You might have opposite othopedical problems... and very small feet. Anyway: who's perfect...

    -b
    q-factor is the distance from crank to crank (measured on the outside) and has nothing to do with the pedal axle lenght.
    overall width sure is affected by pedal axle lenght but not so the q-factor.
    i have 8mm space between my feet and crankarm if clipped in on my eggies. so what does that mean? it means i can run ca. 6-7mm shorter axles without touching the cranks. that will give me a 12-14mm shorter overall distance....that's like having a 14mm narrower q-factor. i have euro size 41 with my Sidis. nothing special.

    a shorter pedal allows you to have your feet closer together without having problems with the chainline. shorter pedals will allow for higher cornering speeds too. there's no need to carry extra lenght in pedal axles

  12. #12
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    Quote Originally Posted by nino
    q-factor is the distance from crank to crank (measured on the outside) and has nothing to do with the pedal axle lenght.
    overall width sure is affected by pedal axle lenght but not so the q-factor.
    i have 8mm space between my feet and crankarm if clipped in on my eggies. so what does that mean? it means i can run ca. 6-7mm shorter axles without touching the cranks. that will give me a 12-14mm shorter overall distance....that's like having a 14mm narrower q-factor. i have euro size 41 with my Sidis. nothing special.

    a shorter pedal allows you to have your feet closer together without having problems with the chainline. shorter pedals will allow for higher cornering speeds too. there's no need to carry extra lenght in pedal axles
    I measured it last night and have only 5 mm of space with my Eggbeaters (shoe size 45). I know from experience, that a few mms less and I start rubbing the non-low profile crankarms and the chainstays. I use to have an excellent steel MTB frame which was 12 mm narrower chainstay than my present bike and with a TruVativ Stylo + 108 mm ISIS BB I could still use the Shimano cleats adjusted so my shoe was only 1 mm from the crankarm. By the way, Sidis were always too narrow for my feet...

    See, we are all different and hard to state the final truth in any question related to anatomy...

    -b

  13. #13
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    Quote Originally Posted by dmrun148
    its for singlespeed
    Would not that primary constraint in your setup is the rear cog chainline? So that any difference would be only in pedals and cleat position?

  14. #14
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    I agree Eggbeaters are wiiiiide.... their new Quattro pedal is a few (~2) millimeters shorter.

  15. #15
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    i run isis 108mm with triple ring and xrt 950 front der. The front der works well, but it´s difficult to set it up properly. Most mtb front ders. are designeg to work with wide q-factor cranksets.

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    Q-factor is independent of chainline

    Quote Originally Posted by MaL�L
    i run isis 108mm with triple ring and xrt 950 front der. The front der works well, but it�s difficult to set it up properly. Most mtb front ders. are designeg to work with wide q-factor cranksets.
    Q-factor can be (and usually is) independent of the chainline. My Ritchey Logic crank has the same chainline as any Shimano triple crank but the q-factor is as much as 15 mm smaller (155mm vs. 170mm). It's all in the bend/pitch or the crank arm. Consequently, front der. adjustment is not usually a problem, although the tolerance can be a bit tight between the big ring and the outer plate of the der.

  17. #17
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    ritchey cranksets are diferent

    as you said, q factor can be independent of the chainline. But is no usual. In fact, if you use a crankset designed for a 50mm chainline when using a 113mm bb, that same crankset will obviously have a 47,5mm chainline when using a 108mm BB.

    So ritchey are designed to have a 50mm chainline with shorter than 113bb. But that´s not usual, the usual is have the correct chainline for triple but with "standar" 113mm bb.

    The problem in this cases is not the small q-factor, the problem is the wrong chainline.

    I use a adjustable chainline bb (frm). but this is not true because it modify the chainline but it also moves the cente rof gravity of the Q-factor length a few mm to the right side of the bike.

    Do you understand what i mean?

    thanks

  18. #18
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    What I really wanted to say is...

    Quote Originally Posted by MaLóL
    as you said, q factor can be independent of the chainline. But is no usual.
    The point I meant to make was that if Shimano/Race Face/Trutativ or whoever wanted to, they could make a smaller chainline by changing the pitch of the crank arms. I don't understand why they don't...

  19. #19
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    smaller chainline? why?

    what we need is bigger chainlines, like the ritchey cranks, not smaller...

  20. #20
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    Oops, meant to say smaller q-factor...

    Quote Originally Posted by MaLóL
    smaller chainline? why?

    what we need is bigger chainlines, like the ritchey cranks, not smaller...
    Sorry, I meant that from my perspective, Q-factor should generally be smaller than the "big" manufacturers make their cranks. A crank with an appropriate chainline can be made that has a narrow Q-factor -- witness Ritchey cranks. Just make the crank arms more straight up and down... Of course, the frame manufacturers might have an issue with designing chainstays that would clear narrow Q-factor cranks.

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