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Racer Tech Thread

Old 10-11-17, 11:26 AM
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I think the standard should be arms, spider, rings, bolts, and BB.

Pedals should not be included.
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Old 10-11-17, 11:50 AM
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Agreed.
Now with some frames having empty BB shells (PF30) and other having threads even that is kinda hard to measure as the frame can take some of the weight. Although the threads take more weight on both parts frame and cups usually.

Any comments on pedal spindle width?
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Old 10-11-17, 02:13 PM
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Solution looking for a problem in your, puppy's, case. If his foot was that broad or his fit had issues that require it you would have been well aware many years ago.
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Old 10-11-17, 03:41 PM
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Originally Posted by miyata man
Solution looking for a problem in your, puppy's, case. If his foot was that broad or his fit had issues that require it you would have been well aware many years ago.
If you have big feet (I wear 46s) you can have issues with the heel striking the chainstays. It's very much frame-dependant; I have no issues with my new Allez Sprint frameset but have worn spots on my Look 585's stays even though the chainstays are longer on the Look.
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Old 10-11-17, 05:21 PM
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Coach added spacers for a PM and he liked it. I didn't think it was a big feet thing. Coach and puppy are 44.
I was wondering if it did a q-factor thing. I guess the best way to deal with that is get bigger q-factor cranks, but if you want to stick with a brand, I'm not aware of that option.

On Q-factor I always thought less was better. I don't know racers that care. I'm just ordering and it is an option, so I thought I'd ask.
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Old 10-11-17, 05:33 PM
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Of the physiological issues that could incur a need for longer pedal spindles. A national level U23 rider is an unlikely candidate for most. At that level all solutions to problems are on the table because of the level of expertise being applied. If his coach/fitter/??? says they are needed for that frame, buy the longer spindle version. Otherwise it's just as I said.
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Old 10-11-17, 06:05 PM
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A lot of it is just frame geometry. I whacked my left heel on the seatstay of my Caad 9 so often that I actually wore a hole into it. Happens sometimes on my Tarmac, happens just about never on my Felt AR.
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Old 10-11-17, 06:11 PM
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Old 10-11-17, 08:31 PM
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Originally Posted by globecanvas
There's some inconsistency about what exactly is included in various advertised crank weights.
cannondale was great at perpetuating that myth that the hollowgram was the lightest crankset, and others repeated that claim without verifying. they often failed to include the required spindle, which is a captive part of most other cranksets.

chainring choice is definitely a factor; there have been stupid-light chainrings which suck (an s-works model stands out from about 8 or 9 years ago as exemplifying this), but it is hard to standardize for that as some cranksets *require* use of a particular chainring (eg DA 9000).

specialized gen III carbon arms (incl spindle) + mandatory spacers/lock ring / dust cap come to 338g (actual).
hollowgram aluminum arms (SiSL2) + spindle + spacers = 375g (actual).

same spindle width and diameter, same arm length.

that's not much of a difference, but it IS an apples-to-apples difference, and it's not in favor of the one who claimed to be lightest.

one can use the ultralight spiderring (53/39) for the cannondale at a stated 175g; a specialized carbon spider + dura ace rings & bolts (which are certainly not light but are notably better) = 200g.

that brings the hollowgram to within 12g, but a set of lightweight rings on the specialized instead of the DA rings would increase that difference.

NBD, except that cannondale has claimed the 'lightest crankset' thing for a long time.

of course, some may prefer a relatively light set of aluminum cranks to carbon cranks. i personally don't have any issue (riding OR crashing!) carbon cranks, and i use carbon cranks off-road (MTB & CX), too.
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Old 10-11-17, 08:33 PM
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Regarding longer spindles. A small part of this book (https://www.bloomsbury.com/uk/bike-fit-9781408190302/ by Team Sky's fitter) talks about how in today's state of the art bike fit science, the "stance width" (q-factor, essentially) is a very ill-understood and highly overlooked portion of a bike fit. IIRC, he essentially says that if you have duck feet and if you have crank rub, then consider getting longer spindles
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Old 10-11-17, 08:35 PM
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Originally Posted by topflightpro
I think the standard should be arms, spider, rings, bolts, and BB.

Pedals should not be included.
one could argue whether rings should be included, as there are some weight weenie rings that shift poorly under load, but pedals should certainly NOT be included.

you'll rarely find someone doing apples-to-apples comparisons with ACTUAL weights.

Originally Posted by Doge
Agreed.
Now with some frames having empty BB shells (PF30) and other having threads even that is kinda hard to measure as the frame can take some of the weight. Although the threads take more weight on both parts frame and cups usually.

Any comments on pedal spindle width?
one can standardize for that if they want to. compare the specialized FACT cranks (30mm) to the bb30 version of sram road cranks to the cannondale cranks (w/ spindle). include all required parts to make it work (e.g., wave washers, lock rings, etc), and exclude the rest of the BB (BB cups/circlips + bearings are part of the BB, not the crank, but spacers are part of the crankset).

spacers add up to a gram or 3 at the most, so that's not a huge issue either.
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Old 10-11-17, 08:41 PM
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Originally Posted by Doge
Coach added spacers for a PM and he liked it. I didn't think it was a big feet thing. Coach and puppy are 44.
I was wondering if it did a q-factor thing. I guess the best way to deal with that is get bigger q-factor cranks, but if you want to stick with a brand, I'm not aware of that option.

On Q-factor I always thought less was better. I don't know racers that care. I'm just ordering and it is an option, so I thought I'd ask.
you're right in that most of the time one must switch to a different brand crank to adjust Q *at the crank*, but there have been cases where some cranks were offered in different Q factors.

sram MTB was that way until recently (156 & 168Q), but with the move to BOOST the narrower Q cranks have gone away. not sure if they ever had different Q factors on the road side.

what pedals does your boy prefer?

i think speedplay offers different axles as an option. LOOK does not (or did not), but you could buy aftermarket spindles (they don't say they are LOOK compatible as a protective measure) to allow for a wider stance. you could also buy aftermarket Ti spindles the same way.

come to think of it, there was a time i was experimenting with different spindle widths, and i think i may still have a set of longer LOOK spindles if you need them. it's a pretty easy swap.

Edit to add: Pretty sure DA pedals come in different widths, too.

Last edited by tetonrider; 10-11-17 at 08:47 PM.
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Old 10-11-17, 08:47 PM
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Originally Posted by TheKillerPenguin
A lot of it is just frame geometry. I whacked my left heel on the seatstay of my Caad 9 so often that I actually wore a hole into it. Happens sometimes on my Tarmac, happens just about never on my Felt AR.
there are a few factors:
* the Q-factor of the crank
* how much and how soon the chain stay flares out
* position of cleats on rider's shoes
* float (more float = more chance of this happening)
* whether the rider pedals "heels-in"
* the shoe size of the rider; bigger shoes = more chance of rub

this has been more an issue on the MTB side in recent years as width at the rear hub is wider than for road and frame manufacturers have been adjusting the width of the stays to accommodate wider and wider tires.

147Q is possible on a road bike (that's for DA; specialized road cranks are narrower @ <138Q). the specialized MTB crank, on the other hand is 167Q. go check out Q for fat bikes!

Last edited by tetonrider; 10-14-17 at 02:05 PM.
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Old 10-11-17, 08:58 PM
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Originally Posted by tetonrider
this has been more an issue on the MTB side in recent years as width at the rear hub is wider than for road and frame manufacturers have been adjusting the width of the stays to accommodate wider and wider tires.
For the purpose of this conversation I feel the need to point out this was a major issue with all roads bikes that married CX or larger tire sizes with endurance road bike geo. Mostly by inexperienced builders until a few years after it was a thing the larger manufacturers jumped on the band wagon.

TKP, this ties in with your CAAD in what sounds like poor bike design work to fit some shortsighted ideal of functionality. The whole compact geo/aero thing has produced a fair amount of bikes that aren't good at being bikes. I can't say what your issue was so don't take issue with the duck foot mirror.

Last edited by miyata man; 10-11-17 at 09:01 PM.
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Old 10-11-17, 09:49 PM
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Originally Posted by tetonrider
...

what pedals does your boy prefer?
Don't know. Never made a thing of it. He just rides what we get and if he thinks it is better - he goes faster.
Which is why I'm asking...


Originally Posted by tetonrider
...
Edit to add: Pretty sure DA pedals come in different widths, too.
They do. Settled on Shimano when buying individual components.

Last edited by Doge; 10-11-17 at 09:55 PM.
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Old 10-11-17, 10:52 PM
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Originally Posted by Doge

On Q-factor I always thought less was better. I don't know racers that care. I'm just ordering and it is an option, so I thought I'd ask.
like many things, some care a great deal, some don't care at all.

some people can feel if their saddle is out of position by 2mm and others cannot; which camp does your boy fall in?

unless you are talking some extreme, the range of difference in Q factor is not very large, and odds are a wider stance may be noticed more for the fact that effective saddle height changed.

popular thinking is that narrower is preferable (and faster, aerodynamically), but there is no right answer for everyone.

people make a big deal about a change from 172.5 to 170 cranks (or even 167.5), but the changes are small and easily adapted to -- for MOST people.

bottom line: depending on what pedals your kid uses, you can adjust spindle length to change stance even if you can't get wider Q from the cranks. i tried to ask which pedals your boy uses, but you said you didn't know.

small changes in position *tend to* matter less because a rider is on and off the bike (in CX), there's suspension involves (MTB), people are in/out of the saddle more, etc. tends to fall more into noise during actual racing.
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Old 10-12-17, 07:15 AM
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Originally Posted by tetonrider
one could argue whether rings should be included, as there are some weight weenie rings that shift poorly under load, but pedals should certainly NOT be included.
I include rings because, as you mentioned earlier, some cranksets only work with certain rings.

The other issue is the spider. It should be included, but Cannondale saves weight be marrying the spider and rings.


Originally Posted by tetonrider
i think speedplay offers different axles as an option. LOOK does not (or did not), but you could buy aftermarket spindles (they don't say they are LOOK compatible as a protective measure) to allow for a wider stance. you could also buy aftermarket Ti spindles the same way.
I think this is correct.

Also, if the difference is minor, one can add an extra pedal washer to increase the spacing. I do this on my right leg as my foot naturally angles out, meaning when pedaling, my heal angles in.
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Old 10-12-17, 07:57 AM
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Originally Posted by tetonrider
there are a few factors:
* the Q-factor of the crank
* how much and how soon the chain stay flares out
* position of cleats on rider's shoes
* float (more float = more chance of this happening)
* whether the rider pedals "heels-in"
* the shoe size of the rider; bigger shoes = more chance of rub

this has been more an issue on the MTB side in recent years as width at the rear hub is wider than for road and frame manufacturers have been adjusting the width of the stays to accommodate wider and wider tires.

147Q is possible on a road bike (that's for specialized; i think shimano cranks are the same). the specialized MTB crank is 167Q. go check out Q for fat bikes!
Yeah, for a while I was riding bb386 which was nice because it kept my heel from whacking on the frame I was riding at the time (it had flared seat stays). I honestly can't feel the q-factor difference between it and BB 30 though, even though it is substantial!
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Old 10-12-17, 08:51 AM
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woah tkp when did you get a felt? been eyeing one of those myself.
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Old 10-12-17, 09:19 AM
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mmm back around KSR! I love it. Highly recommend! [MENTION=360087]dz_nuzz[/MENTION] will sing their praises as well I am sure.
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Old 10-12-17, 09:31 AM
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Already have sung them praises to Mikey. Wonder if there is a reason why a bunch of us ride em ?

Side note: I believe that BB386 was designed to keep the same Q-factor as BB30 cranks. If you look at the differences between the cranks typically BB30 cranks flared outwards from the frame where BB386 typically were straight.

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Old 10-12-17, 09:45 AM
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Oh duh, I think you're right. Straighter crank arms and all that.
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Old 10-12-17, 01:57 PM
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Originally Posted by TheKillerPenguin
Yeah, for a while I was riding bb386 which was nice because it kept my heel from whacking on the frame I was riding at the time (it had flared seat stays). I honestly can't feel the q-factor difference between it and BB 30 though, even though it is substantial!
minor point on nomenclature, but perhaps material:

Q-factor applies to cranks, not bottom brackets or pedals. Q is measured as the distance from the outside of one arm @ the pedal to the outside of the other.

BB30, BSA and BB386 may affect crank options, and the chain stays of a bike may limit Q-factor (most commonly on MTBs these days); the BB itself does not have a Q-factor associated with it.

some wider bottom brackets will require crank arms with less flare/curvature in order to achieve a given Q than a narrower BB (e.g., BB30).

also, while pedal spindle width may contribute to a wider or narrower stance, that is technically a separate from Q.

Q + spindle length + cleat positioning all affect stance.

generally spacers between crank arm and pedal are viewed as undesirable, particularly for carbon cranks. it doesn't mean one won't get away with it, but they're not typically used. (by spacer i mean more than a thin washer used to protect the crank from the pedal.)
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Old 10-12-17, 02:07 PM
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Originally Posted by dz_nuzz
Side note: I believe that BB386 was designed to keep the same Q-factor as BB30 cranks. If you look at the differences between the cranks typically BB30 cranks flared outwards from the frame where BB386 typically were straight.
Originally Posted by TheKillerPenguin
Oh duh, I think you're right. Straighter crank arms and all that.
aside from aesthetics, the flare of crank arms most often is done so that cranks do not come too close to chain stays.

this usually isn't a problem on road bikes, but bikes with fatter tires (MTB -- and even moreso fat bikes) require wider stays and the width happens closer to the BB. you don't want too wide a stance, so crank manufacturers tread a line to be compatible with frames but not hitting the frame.

there are specs for all of this.

wider BBs necessitate that crank arms are more straight to achieve a narrow Q vs. a narrow BB (all else equal).

crank arm length comes into play, too; longer arms have a greater likelihood of hitting chainstays, and they are less tolerant of float in that the riders' heels has a greater chance of hitting the stay.

i think BB386 came about to offer larger bearings (diameter) spaced further apart (width) -- kind of a best-of-both-worlds for BB30 and 24mm bottom brackets.
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Old 10-12-17, 02:16 PM
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Originally Posted by tetonrider
...
this usually isn't a problem on road bikes, but bikes with fatter tires (MTB -- and even moreso fat bikes) require wider stays and the width happens closer to the BB. you don't want too wide a stance, so crank manufacturers tread a line to be compatible with frames but not hitting the frame.
...
And Tandems with weird 160mm rear spacing.

In the day I had three rings on the right of the tandem (Campy C-Record), none on the left. My spacing was 140 and that was long then. That was also the day of square tapered spindles and you could find spindles that would affect the Q, shift right or left and the BB I used had lock rings on both side of the cups so I could also adjust left and right about 3 threads or so.
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