which road bike is better?

[Christine Tham]

Just thought that I'd chime in and say that the TCR line is full race geometry. The TCR Alliance has the same geometry as the TCR Advanced and Advanced SL bikes which are ProTour racers. It doesn't mean it's uncomfortable for everyone but it's certainly more aggressive than something like the Defy series.

Sounds like marketing hype to me.

Here are actual published geometry data for an "M" bicycle in the Giant line

Seat tube angle:

• TCR Advanced SL = 73
• TCR Alliance = 73
• Defy Advanced = 73

So, which one is more "aggressive"?

You can compare other measurements as well - the differences between the TCR and the Defy frames are minimal.

It's clever marketing from Giant's perspective - they have a huge range seemingly targeted to every type of rider but in actuality the differences are minimal, or related to componentry rather than frame shapes. For example, I have a TCR (Tweety) and a Cypress (Kitty) - one is marketed as a racing bike, the other as a leisure bike for women. Guess what - the geometries between them are very similar and they actually have very similar riding positions. What is different is the lightness/stiffness of the frame, the quality of the components, etc etc.

As a comparison, the Trinity Advanced SL (which does have an aggressive geometry for time trials and triathlon) has a seat tube angle of 74.1 (or 77.5, depending on where you are measuring it).

From memory, seat tube angles of above 78 are illegal (from UCI perspective), so the Trinity is pretty close to the limit.

[thomas_cho]

You need to consider chainstay length (longer for Defy), headtube angle (shallower for Defy), overall wheelbase (longer for Defy) as these factors contribute to the handling of the bike. You may think they are small, but they make all the difference in frame geometry. All these factors make the TCR racier (twitchier) as opposed to the Defy which will be relatively more stable (or slower to respond).

Furthermore, headtube lengths are longer in the Defy series. Which means for a given size the rider will not be able to lower the handlebar position as much for a Defy than for the TCR. The TCR offers the posibility of a more agressive riding position than the Defy.

Giant Tri-bikes' geometry are designed for the rider to ride comfortable in the aero position on aero bars.

Having said that, Cervelo does not market their "relaxed" geometry RS model as a relaxed bike. Instead they make claims that some professional riders choose the RS version as it simply suits the rider.

[Christine Tham]

You need to consider chainstay length (longer for Defy), headtube angle (shallower for Defy), overall wheelbase (longer for Defy) as these factors contribute to the handling of the bike. You may think they are small, but they make all the difference in frame geometry. All these factors make the TCR racier (twitchier) as opposed to the Defy which will be relatively more stable (or slower to respond).

Furthermore, headtube lengths are longer in the Defy series. Which means for a given size the rider will not be able to lower the handlebar position as much for a Defy than for the TCR.

The differences are minimal, and feels minimal as well when riding. I have tried TCR, OCR (older version of Defy) and you know what I have trouble distinguishing between the two from a riding and handling perspective.

Now if the Defy had a seat tube angle of say 71, I would agree that it should feel more relaxed. Actually, it would be nice if Giant made a good touring bike, I would consider buying it.

[thomas_cho]

You are entitled to how you feel on the bikes.

But the geometry differences are there, and they are there for a reason.

[Christine Tham]

You are entitled to how you feel on the bikes.

But the geometry differences are there, and they are there for a reason.

As far as I know, there is no conclusive data that demonstrate performance/handling differences between, say, normal frames and compact frames.

And yet the geometry differences between these kind of frames are far greater than the tiny differences between TCR and Defy.

Of course, if you have data showing differences in performance/handling between the TCR and Defy (on the same rider), I would be very interested in seeing them.

[thomas_cho]

As far as I know, there is no conclusive data that demonstrate performance/handling differences between, say, normal frames and compact frames.

And yet the geometry differences between these kind of frames are far greater than the tiny differences between TCR and Defy.

Well, see here for Giant's take on compact frames. Essentially you can have a compact frame and a traditional frame with the same factors that affect handling as I have pointed out. Re-paraphrasing what the Giant website states, a compact frame is simply one where the front and rear triangle is made smaller by creating a sloping top tube. Doesnt affect headtube angle, seat-tube angle, trail, chain-stay length, etc. So its little wonder there is minimal differences so to speak. So to say that there is a lot of geometry differences is not entirely accurate. I am not sure why you claim there are large geometry differences between a compact frame, and traditional frame.

Of course, if you have data showing differences in performance/handling between the TCR and Defy (on the same rider), I would be very interested in seeing them.

Data, well the sort you are after I have not come across. What I have come across on the internet are views on the issue

1. Zinn's little write up on head tube angles here
2. Here is another (not sure about the author but it touches on the key issues)

Plenty more on the web if you can be bothered to search. I am not saying there is definitive formula for the perfect handling frame, but the relationships between frame geometry and how one feels on the bike is there.

[Christine Tham]

I am not sure why you claim there are large geometry differences between a compact frame, and traditional frame.

I made no such claim. You were making a point that small differences between the TCR and Defy geometry are significant - I am simply observing that these differences are not bigger than the differences between normal and compact frames.

I think you are missing the point here - we are not debating about the subtleties of frame design and geometries.

There seems to be a suggestion in several posts that the TCR has an "aggressive" frame that will make the riding position "uncomfortable."

What I'm pointing out is that the seat tube angle of the TCR is in fact completely standard and no different from other bikes in Giant's range (or indeed other manufacturers).

As you know and I know, there are only 5 contact points between the rider and the bicycle. If the seat tube angle is the same between two bicycles, it should be possible to fit a rider such that the relative positioning of the rider with respect to the bicycle is identical across the two bicycles, therefore from a "rider positioning comfort" perspective the two bicycles should be identical.

*That* was the point I was making. That's certainly proven in my case - I have two bicycles targeted to very different riders, and yet because they have the same seat tube angle I have adjusted both of them so that the positioning of my body with respect to the pedals and saddle are effectively identical. So the TCR is as "aggressive" as a leisure/comfort bike.

As for differences in chain stay lengths etc. - yes, they can potentially impact performance/handling etc. but there is no concrete evidence, and in any case we are moving beyond the topic of rider positioning comfort.

Plenty more on the web if you can be bothered to search. I am not saying there is definitive formula for the perfect handling frame, but the relationships between frame geometry and how one feels on the bike is there.

There are certainly lots of subjective opinion. However, very little actual data.

[waynohh]

The largest factor for a "aggressive" bike is the smaller angle your body makes. i.e. the angle that your ankle, hip and shoulder make. Someone riding a hybrid may have an angle of 150 to 180 degrees. Someone on a relaxed road bike might have 130 to 150, someone on a racing bike might have 110 to 130 and a tri bike might have 90 to 100.

The more you reduce the angle, the more upper body weight you support with your arms. That means you have to have the upper body strength to do so, unless you're on aero bars and it also means, the less you weigh, the less pressure on your wrists, etc.

TCR is in a different category than Defy from the factory, though if you slammed the stem down on the Defy you would make them closer. The TCR you don't have the option of moving the handlebars up the 40mm to 50mm difference unless you get some new forks.

If you have a small upper body, then the difference between supporting say 30% of your weight on your hands and 40% may be too subtle to comprehend.

[Christine Tham]

The largest factor for a "aggressive" bike is the smaller angle your body makes. i.e. the angle that your ankle, hip and shoulder make.

That's funny - most books I've read defined the "aggressiveness" of a bicycle to be the seat tube angle, since the riding posture can be adjusted (by changing stem etc.).

Also, if you recall, we were talking about the TCR Alliance W 2009, not a hypothetical bicycle. I can assure you, given I have personally seen this model, that it does not result in an "aggressive" riding position. The top tube length, for example, is shorter than the equivalent men's model.

I would also point out that given I am an owner of a TCR myself, I've found it is capable of being adjusted to a fairly relaxed riding posture. And I'm riding a frame that seems to be slightly larger than optimal for my body (according to fit calculations).

If it really was as uncomfortable to ride as you suggested in an earlier post, I wouldn't be riding 200 km on it every week, would I?

If you have a small upper body, then the difference between supporting say 30% of your weight on your hands and 40% may be too subtle to comprehend.

I can actually ride it with only two fingers touching the shifters. I also rode it for a period with only one hand (whilst my broken finger was healing). Just ask pine - she's seen me going downhill on Akuna bay on the bicycle with only one hand on the handlebar.

I very much doubt that my hands/fingers were supporting anywhere close to 30% of my weight.

[thomas_cho]

Christine, I think you are confusing bike fit with bike handling.

I could put an adjustable stem on a Surly LHT and have it -30 degrees bringing the bars well below the top of the headtube, install a Profile Fast forward seatpost altering the effective seat tube angle, thereby creating an "agressive"(aero) riding position, but the LHT will still feel sluggish taking corners (this is the result of the frame geometry). As you said, you can of course change the bike fit on most frames to suit your riding style.

A person who is contemplating the choice of a new road bike should be aware of handling differences, as that along with an appropriate bike fit will translate into how the rider's experience of the bike.

There is no reason why an aggressive position should be equated to an uncomfortable riding position. However, not everyone would be comfortable nor have the strength to maintain a flat back, aero riding position as the pros do. It differs from person to person. Again this is more an issue of bike fit, rather than the bike itself.

Your experience might differ and thats fine.

[Christine Tham]

Christine, I think you are confusing bike fit with bike handling.

No, I am simply responding to waynohh's post. I have never claimed that all bikes handle the same, but I do claim that you can adjust bike fit such that rider position is identical across different bikes (within certain caveats, like identical seat tube angle).

There is no reason why an aggressive position should be equated to an uncomfortable riding position.

No, and I have never said that either. Others have, though:

No else else has mentioned that the TCR is Giants' most aggressive geometry bike. Most likely an expensive decorative item for the garage after a couple of weeks unless you're a gymnast, etc.

My point was that the specific bicycle in question, which I was speaking from a first hand experience, is neither aggressive nor results in an uncomfortable riding position (provided of course it has been fitted to the rider).

Please, try not to dispute something I did not say. It's easy to make posts like "You are wrong because you said X" when I didn't say X.

[Focusfire]

Let's just say the TCR is optimised towards an aggressive fit. Of course if you want, you can swap out parts to make it less so but why bother even buying a TCR bike if that's not what you want?

[Christine Tham]

Let's just say the TCR is optimised towards an aggressive fit. Of course if you want, you can swap out parts to make it less so but why bother even buying a TCR bike if that's not what you want?

Can you explain exactly how a bicycle can be "optimised" towards an aggressive fit if it has exactly the same seat tube angle, stem tube angle etc. as most other bicycles, and things like stems are stock standard sizes?

Especially since we are talking about a women's bike where Giant has deliberately relaxed a lot of the dimensions, including top tube length?

[Focusfire]

Let's just say the TCR is optimised towards an aggressive fit. Of course if you want, you can swap out parts to make it less so but why bother even buying a TCR bike if that's not what you want?

Can you explain exactly how a bicycle can be "optimised" towards an aggressive fit if it has exactly the same seat tube angle, stem tube angle etc. as most other bicycles, and things like stems are stock standard sizes?

Especially since we are talking about a women's bike where Giant has deliberately relaxed a lot of the dimensions, including top tube length?

Defy and TCR geometry is not the same. Check the Giant website.

[waynohh]

I think Christine's point is that the WOMENS TCR is completely different i.e. "dumbed down" compared with the mens version and is more like a endurance frame with TCR stickers.

[flammer]

Fight, fight, fight!!

But when it's about the finer points of Giants, it's like two deros fighting over a flagon.