TT or regular aero frame?

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aerodynamiq
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Joined: Tue Jul 28, 2015 9:32 am

by aerodynamiq

addictR1 wrote:thanks guys for all your input... i never plan on putting a road bar on a TT frame.. that would just look odd.

guess i'll have to test ride my friend's propel and see what the hype is all about...


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sawyer
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by sawyer

This thread question a bit like asking "why not ride 90mm rims all the time on a road bike". They are more aero. And in every other respect they are inferior for most road riding.
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Tapeworm
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by Tapeworm

FWIW...
1) have run an old TT frame (Issac) in a roadie setup. Handling was like any other bike and worked fine in crits, road races. People who say otherwise, what handling issues are you experiencing? Rider position and cornering lines have seen me through corners on this franken-bike and the TT bike in the skis at a fair clip.

2) such much other woo, I can't even.
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spud
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by spud

^ ditto. Aside from slightly slower steering, it works fine. And it's fast as hell. Of course, I already run a decent amount of drop on my road bike, so this set up isn't that different. You are just rolled forward around the BB.

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Calnago
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by Calnago

"Slightly slower steering"? Slightly, or much slower? Granted it depends on the actual geometries in question, but typically for the same size rider a tt bike is going to have a slacker head tube angle and without a corresponding adjustment to fork offset (rake), will end up having a significant amount of trail. Great for going in a straight line at speed... it's very stable as that's how the bike wants to track, straight and fast. Try going up a relatively steep hill forcing slower speeds behind someone on a nice road bike that is fit well. Watch how their bike tends to track very straight at the front end. Versus on your tt bike, the front end will likely tend to "flop" as your effort goes side to side with each pedal stroke. The road bike's front end just seems to track straight ahead whereas you have to almost fight the tt bike's front end to act the same way. It's not unridable by any means, but it sure isn't as nice as having a nice road bike geometry in the same situation.

And turns tend to carve much nicer and more precisely on the road bike geometry, no feeling like your wheel is going to wash out in the turn, at least not like if you tried a similarly aggressive turn on a tt bike.

That's basically what I've experienced with the different geometries. I had a custom road bike built for me once and the builder chose a fork with rake of 42mm paired to a headtube angle of 72.5 degrees, very slack for my size of frame. This resulted in a trail of over 60mm. That's a lot of trail. Never did like how this bike handled overall, basically exhibiting a lot of the behavior I described above. That's just a snippet of an answer to your question. Clearly a lot of other variables contribute to the overall handling of any rider/frame combo, but that's a quick nutshell explanation of some of the main areas where the two geometries differ in the handling department and feel on the road.
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Tapeworm
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by Tapeworm

^ none of that makes any sense.

I think y'all need to learn how to corner properly. And ride in a straight line.

Lots of woo here.
"Physiology is all just propaganda and lies... all waiting to be disproven by the next study."
"I'm not a real doctor; But I am a real worm; I am an actual worm." - TMBG

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DMF
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by DMF

Calnago, I've already gone somewhat in depth into the actual geometrics of TT/Tri frames and forks here so I won't do it again. But I urge you, please please have an actual look at modern day geometry charts for the two types of bikes from various manufacturers...

What you are saying just doesn't hold true, when looking at the real numbers. You are drawing conclusions and seem to take som wild guesses here. Please just look at the actual numbers of modern bikes instead. Specifically for trail where the differences for most cases are slim to none when looking at size medium or size large bikes...

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Calnago
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by Calnago

@DMF... I wasn't comparing TT frames to tri frames, which essentially are the same thing except for maybe a less aggressive setup for Tri. I was responding to Tapeworm's question as to what the handling differences are between a tt and a road bike, since he said his tt bike handles the same as any other bike. Granted, some tt bikes of old really aren't that different from their road bike counterparts, but that's not the case today, at least for the most part. And in fairness I do not know what the geometry of his Isacc tt bike is.

When I saw your post, I thought... hmmm... so I did compare the geometries of three brands that I know have representative examples of state of the art tt bikes, and road bikes but that was before I came back and realized you were talking about tt vs tri. In any case, I used Trek (Speed concept vs Emonda); Specialized (Shiv vs Tarmac) and Cervelo (P5 vs R3). All show geometry differences consistent with my post above.

I believe I mentioned tt bikes and road bikes in previous above, and I do lump "tri" bikes into the same category as tt bikes when it comes to geometry, so I think we are on the same page there. :beerchug:
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