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Q-Factor in triple vs. double, what problems, if any?

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Q-Factor in triple vs. double, what problems, if any?

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Old 12-13-10 | 05:44 PM
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First, make certain that the Q factor is different between the two cranks. Don't assume. Although BF wisdom (such as it is) will almost always claim that triples are wider between the pedals, it's not necessarily so.

Second, if one or the other crank is wider, make certain that the wider Q factor isn't the correct Q factor. It may be some other issue that's causing the problem. For women, it can often be that a little more space between the pedals is a good thing. (And, I wouldn't be shocked to find some compact somewhere that's wider than some triple.)

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Old 12-13-10 | 05:50 PM
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Originally Posted by DaveSSS
Carbon Unit...

You've made the proper comparison. You won't even notice the 23-26-29 jumps - they're much more tolerable at the low end, when the going gets tough. The top and low end gears will be nearly identical.
Thanks for the feedback. I wasn't sure if going with a 12-27 or 12-29 was the better option. I would rarely, if ever, use a 29 but then when you need it, it is great to have it. If the jumps weren't too bad, I would probably go with the 12-29. The jumps on a 12-27 are something like 23-25-27. The rest of the cassette is the same between a 12-27 and a 12-29.
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Old 12-13-10 | 06:03 PM
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Originally Posted by FlashBazbo
First, make certain that the Q factor is different between the two cranks. Don't assume. Although BF wisdom (such as it is) will almost always claim that triples are wider between the pedals, it's not necessarily so.

Second, if one or the other crank is wider, make certain that the wider Q factor isn't the correct Q factor. It may be some other issue that's causing the problem. For women, it can often be that a little more space between the pedals is a good thing. (And, I wouldn't be shocked to find some compact somewhere that's wider than some triple.)
It's pretty rare to find a double that's wider than a triple, especially for the modern external bearing, 2 piece types.
Normally, to do such a thing, you would have to use a really wide square taper, probably for frame clearance issues, which a road bike will never have and using such a wide axle will also give chainline problems. Now, if this was a MTB crank we're talking about, then it's possible, but for road cranks, it's very unlikely that a double will have a wider Q-factor than a triple.
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Old 12-13-10 | 06:44 PM
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Originally Posted by Carbon Unit
I almost never use the smallest chain ring on my triple. Maybe once a year I might use it....There is probably a part of me that wants something that is new and cool too...It all works but a new compact group would be like having a new bike to me.
It's the same with me.
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Old 12-13-10 | 07:58 PM
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All of the input is great, but I didn't want to start another triple vs. compact debate.
I'm more concerned about a wider Q-factor predisposing me or my wife to injuries. I doubt that the triple caused her hip problem, but I'm curious about what effects it has on an injury that is already there.
If the wide Q-factor could hurt either one of us, I wouldn't hesitate to make both compact doubles.
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Old 12-14-10 | 08:43 AM
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A 34/27 low gear is like a 30/24, so it's a little lower than a 30/23. If the 30/26 is rarely, used then the 34/27 might be just the ticket.
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Old 12-14-10 | 09:22 AM
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For me, a wide crank causes very bad knee pain for me. Switching to speedplays helped because of the float and then when I went to a low q factor crank, my knee paid disappeared.
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Old 12-14-10 | 09:32 AM
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Some riders may also benefit from Lemond Wedges. I've read postings from Speedplay users who complain about the outer edge of the lolipop wearing out. The problem is foot misalignment, where the outer edge of the cleat is all that contacts the pedal. If the feet are properly aligned, there will be relatively even contact and wear. I discovered that I had the opposite problem, but only with my left foot. The spring clips of my X type cleat wore a groove in the pedal spindle. That a sign of forefoot valgus that require shim with the thick side on the outer part of the cleat.

I've ridden behind riders with some very odd leg movement while pedaling. One of the most common is the knee(s) flaring out much wider at the top of the stroke, rather than straight up and down. I've also seen knees that appear to be rotating in a circle at the top of the stroke and folls with a lot of side to side heel movmement.

https://www.cambriabike.com/shopexd.a...m=051000001100
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