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So I understand that having a fork with a 1.5" steerer in a 1.5" steer tube would make for a that much stiffer front end of the bike. What I'm wondering about though is when you're just using a fork with a 1 1/8" steerer on a bike with a 1.5" steer tube, is that bike as strong as any other bike with a 1 1/8" steer tube or is it actually potentially weaker because you're using reducers to take up the extra space. See what I'm saying? Is a bike with a 1.5" steer tube running a fork with a 1 1/8" steerer just as strong as a bike with the same fork but a 1 1/8" steer tube instead?
 

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~Disc~Golf~
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my guess is this... If every thing else is even - same tube thickness, welds, geometry etc., the fork would be just as strong.
both frames would be as strong as well. the adapters take up roughly the same amount of 'real-estate' as the cups would in the head tube.
 

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Capricious youth...
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The Gabelsteifigkeit tells me everything I need to knowzzzzz!!!!!

:D

In all seriousness, I ran reducers with a King headset with my 1 1/8th Totem on my 7point, and never had a problem. The headset never even loosened up on me. VERY stiff, but certainly a little heavier than just running a 1point5 headset with a 1point5 steertube.

Put 9 days of riding this summer at Northstar on that bike, and never had a problem with stiffness or rigidity.
 

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Sorry, basically, the first column illustrates the stiffness going from 1.125 to 1.5. 1.5 showed no measurable torsional flex, which is why there's no value there. The second row across is the braking stiffness.

On the right hand, they compared a QR to a 15mm QR, and as you can see, there isn't too much of a stiffness gain. In fact, they put it in perspective of the stiffness to weight ratio, and it was actually lower with a 15mm. More weight and not a proportional amount of stiffness gain.
 

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Jerk_Chicken said:
On the right hand, they compared a QR to a 15mm QR, and as you can see, there isn't too much of a stiffness gain. In fact, they put it in perspective of the stiffness to weight ratio, and it was actually lower with a 15mm. More weight and not a proportional amount of stiffness gain.
Well that settles that one... I was planning on getting a 15mm set up for my XC bike. I think that I will get a Pike instead.
 

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squish is good
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Jerk_Chicken said:
On the right hand, they compared a QR to a 15mm QR, and as you can see, there isn't too much of a stiffness gain. In fact, they put it in perspective of the stiffness to weight ratio, and it was actually lower with a 15mm. More weight and not a proportional amount of stiffness gain.
Well holy crap. You found data that shows that result!? I mean, I didn't like 15mm before but now...

I really wish the major US mags would run articles like this, I've settled on Decline as a favorite for the time being but even it feels like a big advertisement sometimes.

On the 1.5 thing, I can't tell a difference at the handlebars between any of em. I'm not super impressed with the 1.5 standard personally but I think for some of the really big hucksters it can be beneficial.
 

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Hey JerkChicken,
which magazine had the article on the headtube comparison. Was it the normal BIKE? Ive got this months Mountain BIKE and Mountain Bike Rider and I didnt see it in there.
oh and BTW, make some room in your Private Mailbox. :thumbsup:
 

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Living Ghetto Fabulous!
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sullie said:
Is a bike with a 1.5" steer tube running a fork with a 1 1/8" steerer just as strong as a bike with the same fork but a 1 1/8" steer tube instead?
I tend to believe what all the frame makers are saying on this; more surface area to weld the headtube on and less chance of ovalization due to increased surface area for the headset... ;)
 

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l would compare this data with the motorcycle industry... dang, these bikes are motorcycles, without the motor.

l never took a mechanical engineering course in my life but, seems to me, the bigger circle has a better impact resistance. Headset, frame and the steerer tube where it meets the fork crown. Totem's with 1-1/8" seem to be a smidge We Todd Did.

C-Dale's been using an oversized head tube for years, shoot, l only cracked three of them!!!
 

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i like rocks
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on my bottlerocket, i just got done going from a 1.125 to a 1.5 steerer.

old: fox 36 1.125 steerer, cane creek dbl xc headset, thomson elite 50mm stem, deity 25.4 bars

new: fox 36 1.5 steerer, chris king headset, thomson x4 stem, deity dirty 30 bars.

i weighed the parts before and after, and all in all, the 1.5 conversion saved about 30 grams. the end result: ALL of the parts are significantly burlier, AND i saved a minuscule amount of weight. to top it off, it just like burly cool. and well, theres more, the germans say its stiffer!

so how can you go wrong? no real ride time as its winter.... in chicago.... but i doubt i'll feel any stiffness increase, and its not like i had any reliability problems with the old setup, but i'm still awfully glad i made the swap.
 
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