FrankTuna

I've been getting serious about riding this year, and plan to train over the winter with an indoor trainer and I'm working to drop some lbs. I can hang with 18mph group rides and have done 2 centuries this year, but want to join the fast 21-22 mph group rides and do at least 4 centuries next year.

I'm looking to buy a dedicated road bike, preferably carbon that can run true 32mm tires. I already have a Topstone that's great, but I'd like to keep that set up with big tires and a rear rack.

My head is spinning with all the choices out there and I'm 6'5" so no local shops have anything in my size in stock. My Topstone is an XL, with 40.2 cm reach, 120 mm stem, and 64 cm stack. The Supersix is supposed to be a fast, race type road bike and the 62 cm has a 40.6 reach and 63.4 cm stack. That seems pretty close to my Topstone which is supposed to be a more relaxed, endurance geometry.

What would make the Supersix faster? More aero tube shapes and less weight? How much faster would this be vs an endurance bike at the same weight like a Synapse? It seems to me based on the measurements that you could get a similar fit on either, or am I missing something?

caloso

The engine.

FrankTuna

I get that...and that's a common refrain. But if the engine was the only variable, why do we cyclists worry about all the other stuff? Given the same rider on a Supersix and a Synapse, with the same wheels and fit, do you think there's no difference in performance?

RShantz

Obviously the engine is the main factor. But to try to answer your question: The race bike is likely to be lighter and likely to feel like it accelerates better. Rake may be different which would impact steering.

RShantz

Much of the items discussed on this forum relate to marginal gains.

topflightpro

It's not just about stack and reach.

Endurace frames also tend to have slacker angles and longer wheelbases, which result in a more comfortable, less twitch ride.

Also, bike sizing differs by company. One brand's 56 may be another's 54. So, while your endurance Topstone has a similar stack and reach to the racier Cannondale, that could just be due to how the two companies size their bikes.

FrankTuna

Well I don't think I'd look good with shaved legs, so I'm looking at my other options

FrankTuna

I've been thinking about the wheelbase issue too, which must be related to the angles too. I had a Trek gravel bike for a few months and sold it because I wasn't happy with the fit. I had alot of toe overlap, and that's not an issue with the Topstone since that has a long wheelbase. Is some toe overlap to be expected on a typical road bike?

melikebikey35

This. Endurance bikes are designed around comfort. Then race bikes are designed around performance...stiffer, more responsive, quicker handling, etc. So, while overall speed between the too may not differ much, how they feel/get up to that speed can be very different.

With that said, the best thing that you can do to improve overall speed, is upgrading your wheels/tires. A stiff, light and aero wheel on 25-28mm race rubber will provide a very noticeable gain.

caloso

The Supersix will likely be slightly lighter and quicker steering. Which means that it will corner and accelerate better, and climb faster. If you're racing crits or hilly road races, that would be important to you. But for centuries and group rides, I don't think it would make much difference at all. Any aero difference can be made up with a tighter jersey and bending your elbows more.

I'd get whichever one fits better. Or comes from the shop that's nicer.

CliffordK

One would have to look at each bike/brand. Other features are that most brands are trying to specifically add some flex to the endurance bikes.

So, Specialized adds Zerts and the Future Shock in the Roubaix and a few other bikes.
Trek uses IsoSpeed decouplers in critical locations.

Another thing to look at is tire sizes.

Traditionally, many of the road bikes were topping at about 25mm, or perhaps 28mm tire sizes.

At 6'5", how heavy are you? You might find yourself leaning towards 28mm, or perhaps 32mm tires. Anyway, I would certainly put tire clearance as one of the criteria that I'd use with choosing a new bike.

bbbean 

The geometry isn't similar.

FrankTuna2

Cannondale Synapse (first) vs Supersix (second) for a 61/62cm frame...

Reach: 40.2/40.6
Top tube: 60.4/61.1
Stack: 64.0/63.4
Wheelbase (both): 102.8
Head tube angle (both): 73°
Stand over: 86.8/87.0
Trail (both): 5.8
Fork rake (both): 4.5
Chain stay: 41/40.8

hefeweizen

FrankTuna
What would make the Supersix faster? More aero tube shapes and less weight? How much faster would this be vs an endurance bike at the same weight like a Synapse? It seems to me based on the measurements that you could get a similar fit on either, or am I missing something?


Bike Frame Stiffness / Pedaling Stiffness
Giant TCR Race 163 / 71
Giant Defy Endurance 141 / 70

topflightpro

The New Evo definitely has a more relaxed geometry than the previous version.

But the Synapse will still have higher bars with a shorter reach.

DaveSSS 

The purpose of using the stack and reach dimensions is to allow bar height and reach to be made the same, with different stem lengths and spacers under the stem or stem angle changes.

What is often overlooked when comparing frames with different stack heights, is the reach value needs to be adjusted to the same stack height on both frames. If you're trying to decide between two sizes, with a 20mm difference in stack height, 6mm should be subtracted from the reach of the smaller frame, assuming that the smaller frame will need 20mm of spacer under the stem and none would be used on the larger frame.

You often see the reach of frames only increasing by a few millimeters between sizes, while the stack changes in 15-20mm increments. This makes more sense when a 4mm difference becomes 10mm, once the reach is adjusted to the same stack height on both frames.

Darth Lefty 

There are a lot of "marginal gains" to be found between an aluminum Topstone and a carbon racing bike. You will be able to tell the difference.

RShantz

I'd be curious to know how much faster the racing bike frame would be if the two bikes were at least on the same tires and he road in a similar position for aero purposes.

He may enjoy the ride more based on how the bike feels, but solely discussing speed I'm just not certain how much faster, if any, the race frame would be.

N00b_Cyclist

If you haven't already...what's keeping you from looking at the new Trek Domane? Comes with 32 by default, and can fit wider. Can also go down to a 25-28 if you're looking for something a little more race-like. While the bike is pretty heavy on the lower end, it dips down into the 17lbs range on the higher end bikes. Which isn't that bad for an endurance bike. Again, if we're talking about "marginal gains"...I could lose 20lbs of body weight before I start worrying about the fact that my bike is 2lbs heavier than my buddies. Not sure if that's true in your case or not, but it might be worth a look if you're thinking of doing a lot of centuries.

Chi_Z

i think a cheaper option is to sell the alloy topstone then get the carbon topstone and another wheelset. If you enjoy your current groupset you can just sell the frameset and move everything over. My Niner is my everything in one bike.

ridingfool

For me not much I don’t have those 2 bikes to compare . But I do have a BMC granfondo an indurance bike and a few race bike and for me the speed is about the same I feel the specialized tarmac handles a little better into turns and on descends . But as for speed never say to myself I’m taking out one or the other bikes so I can be faster on a ride that day.

billyymc

Or fictional gains.

N00b_Cyclist

Lulz. I mean, there are many kinds of people who ride bikes...some of those fall into the category of well...people who fish for any and all gains, fictional or otherwise. Not my place to judge.

big john

I ride larger frames (62-64) and no bike I've owned in 35 years has had toe overlap. I also have big feet (49). If any of them did have it I didn't notice.

For recreational cyclists the speed differences between bikes isn't going to be much if the bikes are reasonably similar. The fit/comfort is important for century type rides.

I've always used 23 tires for everything but am thinking about trying something larger.

Why is there a FrankTuna2?

mstateglfr 

You last paragraph is the best reason for stack and reach to exist- it normalizes what frame sizes are called. So yes while isnt just about stack and reach, you cire a good reason for those measurements to be heavily considered.