Taller head tube or reversed stem, which is safer? - Page 2

George, here are my specifics…



Bike: 2007 TREK Madone 5.9 (58cm).

Geometry link: http://www2.trekbikes.com/bikes/bike...id=1476000&f=1

Set-up:

- Bontrager 5mm setback seatpost

- Sella Italia Prolink light saddle (set mid rail)

- Stem: Inverted Zipp 145 stem with no spacers

- Bars: Zipp contour (46 cm outside to outside)

- High cadence (mid foot)

- 6’0”, 170, 40 years



I tested the bars again today. Found the new geometry with the flipped stem to be much more comfortable for the hands without too much of a sacrifice in safety. My question is whether I should buy one of the newer Madone frames with the taller head tubes? The way my bike is handling with the flipped stem I feel I have probably already answered my own question, ie. no (not worth the $$$).



However, this still leaves the original question unanswered: Would a new 58cm “performance” Madone with a 3cm taller head tube and a downward angled stem be safer than my model with a flipped stem?



Mike

Quick questions, what length stem? C-C.
Crank length?

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Cheers,
George.

The Zipp 145 stem has a 10 degree angle. The height change for reversing the stem would be approximately 1.72" (44mm) for a 120mm reach example. Approximately 1.57" (40mm) for a 110mm example.

I can not see raising or lowering the torso by those amounts to cause the bicycle to somehow become "dangerous" or unsafe. The change in CG would be pretty small...certainly much less changed than riding while sitting up or while in a deep crouch or going nose-down/ass-up in a sprint.

You state that the current setup has no spacers. It is perfectly safe to ride the bike with a 30mm stack of spacers under the stem and the 30mm maximum spacer dimension is limited by the safety of the leverage point of the stem on the steerer tube. Since you are not changing the leverage point of the stem on the steerer tube, you are not inducing an unsafe condition there.

110mm stem

175mm cranks

Looks like the other poster has determined that there is a 4cm difference in height.

I agree with Bob.

Thank you for the response, we are now playing with a full deck.

Was the bike purchased as a result of a professional fitting service and were you fitted to the bike at the time of purchase?

If yes, go back to them, it may not be the right bike for you. The steerer tube is quite steep, the wheel base short, the chainstay short, and with the widely spaced low spoke count wheels, it would be a twitchy bike to ride anyway.

I could many some suggestions as to better fit, but won't as I now believe it is the wrong bike for your purpose.

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Cheers,
George.

I thought you meant up/down - I agree that fore/aft movement is going to make a difference.

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"All that we see and seem is but a dream, within a dream..."

George,

I bought the bike brand new from a LBS. Trek says that my 58cm is good for someone up to 6'2". When I bought the bike I wanted a very low and aggressive fit as I intended to race with it. I could have taken a 60cm most certainly. In the end analysis, the flipped stem is working for me.

I still wonder whether their new model with the taller head tube is any safer than my flipped stem. Perhaps the LBS will have an answer.

Thanks for your interest,

Mike

Mike,

If you stay with the bike, try a zero offset seatpost with a longer (120-125mm) stem and some spacers under the stem.

This will keep the CofG forward, more weight on the front wheel, and raise your hands and sholders a little. Use some bathroom scales under the front wheel before and after.

I still think the bike is too aggressive for a 40 year old.

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Cheers,
George.

The longer head tube is not there for safety. It's there so out of shape yuppies with pot bellies can buy it and pat themselves on the back for having a "race" bike. It's similar to "club" or "american" fit jerseys.

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"You are like the wind and I like the lion. You form the tempest. The sand stings my eyes and the ground is parched. I roar in defiance but you do not hear. But between us there is a difference. I, like the lion, must remain in my place. While you like the wind will never know yours." -- Mulay Hamid El Raisuli, Lord of the Riff, Sultan to the Berbers, Last of the Barbary Pirates

George, try saying that to Ekimov!!!
Seriously, any fit and athletic 40-70yo is going to have no problem with an aggressive riding position if they train in to it and have no specific and chronic skeletal or other limiting disorder.

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"All that we see and seem is but a dream, within a dream..."

Exactly, but Ekimov and other 40-70 y.o. cyclists are lucky they didn't flip their stems, else their bikes would have become wildly dangerous to ride!!!! Look out, Eki! Look ooooouutttttttttt! For God's sake, don't flip that stem! You'll die!

Every stem should come with a sticker on it, sporting a huge skull and crossbones and, in big red capital letters,

FOR GOD'S SAKE, DON'T FLIP THIS STEM!!!!! YOUR BIKE WILL BECOME WILDLY DANGEROUS AND YOU'LL BE LIKELY TO DIE!!!!!

I think we should all spare a prayer, tonight, for all those poor, unknowing cyclists who have flipped their stems and are thusly one step closer to their graves.

Don't laugh. Dangerous changes to your center of gravity can come about from the smallest of things. One time I made the mistake of putting a PowerBar in my jersey pocket, and it so altered my center of gravity I crashed and broke my coccyx.

I think it may also explain why I have such poor mountain biking skillz. I use a flipped Thomson stem. Maybe if I put it right side up I could give Ned Overend a run for his money.

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"You are like the wind and I like the lion. You form the tempest. The sand stings my eyes and the ground is parched. I roar in defiance but you do not hear. But between us there is a difference. I, like the lion, must remain in my place. While you like the wind will never know yours." -- Mulay Hamid El Raisuli, Lord of the Riff, Sultan to the Berbers, Last of the Barbary Pirates

That's nothing. I can feel the balance shift on my bike that's in sync with my breathing. A big inhale in the middle of a turn widens the turn radius by 15.5cm!

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Morphed Bianchi Camaleonte IV 2006, Ridley Damocles 2006, Garmin, Mac

I completely understand. Once doing hill repeats, I took a dump before doing a descent, and I proceeded to develop a speed wobble!

I think we should all email, write, or call Velo News to encourage Leonard Zinn to write an expose on the potentially dangerous effects of peristalsis on bike stability.

I hope you weren't still on the bike at the time. Could be slippery. That's why I bought a saddle with the cutout centre. Assists with the removal of waste products more efficiently.
BTW, what's the hand signal for faeces to make riders behind you aware?