Specialized Tarmac - Sizing for 179cm & leggy

[DaveS]

You really need to know your saddle height and preferred saddle to bar drop. I'm quite a bit more leggy, with an 83cm inseam and 73cm saddle height, at 168cm tall. Since I can handle a 10cm saddle to bar drop, I use a stack height around 525mm. The 54cm has a stack of 544mm. A -6 stem might give you a saddle to bar drop around 8cm, or 10cm with a -17.

On my MTB I have a saddle height of 75cm - (with different pedals / shoes etc, but will give a ball park.)
I don't know my prefered saddle to bar drop as I don't currently ride a road bike.

How do I calcualate the saddle to bar drop on the Tarmac from that?

If your saddle height is 75mm, what I posted above is accurate. The problem is not knowing how much saddle to bar drop you can tolerate. Saddle setback makes a difference. If the saddle is too far forward, it puts too much weight on your hands. Some people fix that problem by raising the bars instead of getting their weight balanced over the saddle. My torso is shorter than yours, so I use 80mm reach bars, so I can use a 110 or 100mm stem. I also use campy, with shorter reach brake hoods.

[alanyu]

You really need to know your saddle height and preferred saddle to bar drop. I'm quite a bit more leggy, with an 83cm inseam and 73cm saddle height, at 168cm tall. Since I can handle a 10cm saddle to bar drop, I use a stack height around 525mm. The 54cm has a stack of 544mm. A -6 stem might give you a saddle to bar drop around 8cm, or 10cm with a -17.

On my MTB I have a saddle height of 75cm - (with different pedals / shoes etc, but will give a ball park.)
I don't know my prefered saddle to bar drop as I don't currently ride a road bike.

How do I calcualate the saddle to bar drop on the Tarmac from that?

If your saddle height is 75mm, what I posted above is accurate. The problem is not knowing how much saddle to bar drop you can tolerate. Saddle setback makes a difference. If the saddle is too far forward, it puts too much weight on your hands. Some people fix that problem by raising the bars instead of getting their weight balanced over the saddle. My torso is shorter than yours, so I use 80mm reach bars, so I can use a 110 or 100mm stem. I also use campy, with shorter reach brake hoods.

He can get a saddle to bar drop around 13cm (saddle top to bar top) max instead of 10cm (STS with a -17 stem) on a 54 frame as his saddle height is 750

[DaveS]

It might help the OP if you explain how you came up with 13cm. He's got 2cm more saddle height and looking at a frame with 17mm more stack than I have. My saddle to bar drop might get to 11cm, but it's certainly not 13. I use the stock 15mm tall bearing cover and no spacer, with a -17 stem. I know I could get 10mm more drop with a 5mm bearing cover. The concern is not about having enough saddle to bar drop, it's about having too much and needing spacers under the stem.

From a geometry standpoint, you start with with vertical height at the saddle, which is the sine of the STA times the saddle height. If it's 75 and the STA is 73, you get 71.7cm. Subtract the stack height of 54.4 and you get 17.3cm. Tfrom there, you have to subtract the bearing cover height, and the stem height to come up with the total saddle to bar drop. I you figure a minimum bearing cover height and 3.5cm for the stem, that comes to about 13cm. It should be no more than 12 a 15mm bearing cover and down to 10 with a -6 stem.

The HTA on my Colnago is only 71.1, so I get 3.5mm of rise at the bars, but that's not much.

[PrimO]

I'm 180cm tall with an 86.5cm inside seam and i ride a 56cm Roubaix. I wouldnt be as flexable as you are OP but i'm not too bad in that dept. I have previously tried 54cm bikes and found the saddle to bars drop too much on longer rides. With the 56cm frame i have less of a drop and the bike fits me perfectly with a 100mm 82deg stem and 10mm spacer under it.

[jadedaid]

Bike fitting is an art, rather than a science. As others have mention it's well worth the money in that it gets you in the ballpark of the fit. You'll know whether the bikes you are looking at are in the right range for you. The caveats being that as you are new to road-biking your position will change as you gain experience, it won't tell you how the bike will feel like to ride in the real world and different fitters have diffenet bike fitting philosophies.

Having played around with various sizes of bikes I think there is no perfect solution if you're leggy (like me). You have to make compromises and given that this is your first road bike I'd say you probably don't know what compromises you want to make yet. If I was in your position I'd get the 54cm. If you're flexible as you say, the stack height should not be an issue. In general I find that although on smaller bikes I struggle with weight distribution more than on larger bikes (owing to proportionally more weight being taken up by your lower half) the steering and handling is generally better. On larger bikes I don't like that the turning pivot is too far ahead, it just feels 'wrong'. But this is all very personal - if you can, ride both and ride them for a while. See what they're like at slow speed, high speed, cornering and if possible on the descent. The Tarmac is a universally acclaimed bike so you can't really go wrong with either. I suspect you will get a better understanding of what you like after you've ridden a few road bikes and have a few thousand miles under your belt.

As for the looks, I know those are important - but I would caution against that. If chasing an aesthetic ideal of a bike has taught me anything it's that looks are imaterial if you're annoyed with the comfort or handling of your bike. I'd rather be riding a 900 dollar alu Allez that handles like I want it to than a 12k wunderbike that isn't quite right for me

[alanyu]

It might help the OP if you explain how you came up with 13cm. He's got 2cm more saddle height and looking at a frame with 17mm more stack than I have. My saddle to bar drop might get to 11cm, but it's certainly not 13. I use the stock 15mm tall bearing cover and no spacer, with a -17 stem. I know I could get 10mm more drop with a 5mm bearing cover. The concern is not about having enough saddle to bar drop, it's about having too much and needing spacers under the stem.

From a geometry standpoint, you start with with vertical height at the saddle, which is the sine of the STA times the saddle height. If it's 75 and the STA is 73, you get 71.7cm. Subtract the stack height of 54.4 and you get 17.3cm. Tfrom there, you have to subtract the bearing cover height, and the stem height to come up with the total saddle to bar drop. I you figure a minimum bearing cover height and 3.5cm for the stem, that comes to about 13cm. It should be no more than 12 a 15mm bearing cover and down to 10 with a -6 stem.

The HTA on my Colnago is only 71.1, so I get 3.5mm of rise at the bars, but that's not much.

Tarmac sl6 size 54 is 73 HTA and 74 STA. The effective STA could be 73 ~ 75 depanding on saddle setback. Vertical saddle height = 75 * sin (73~75) = 71.7 ~ 72.4 cm. Subtract stack then get 17.3 ~ 18.0 cm. It's OK here. Just consider a stocked 15mm headset cover and a -17 stem with 40mm height STS. The effective stack to the center of the bar = 54.4 + (1.5+4/2) * sin (73) = 57.7 cm. Then add the radius of the bar that's 57.7 + 3.18/2 = 59.3 cm, which is the effective stack to the top of the bar. Now the saddle to bar (top) drop is 12.4 ~ 13.1 cm. A 5mm cover can effectively reduce the stack by 1 * sin (73) = 0.96 cm, which means the saddle to bar drop can be 13.3 ~ 14 cm.

sl6 size54 comes with a 100 -6 stem with 3cm (? not sure) spacers, whose saddle to bar drop is around 8cm when saddle height is 75.

And as you mentioned, the concern is really about having too much and needing spacers under the stem. I would add another concern is even that's not enough and one need to flip the stem, which makes the bike ugly. OP don't know what's his acceptable saddle to bar drop is a problem. Based on this I would say 56 could be better considering the stack but it maybe too long and OP may need a short stem.

[boyceuk]

Thanks for all the help and information guys.

So, armed with more knowledge and a tape measure I went back for a second test ride!
I tried a Specialized Tarmac in 54 and 56, and for comparison the less aggressive H2 Trek Emonda in 54 and 56.

We instantly agreed both 56s were too stretched out as my elbows were locked and I felt like I was stearing something out in front of me.
56 Emonda has a 387 reach + 100mm stem + 100mm bars = 587 total
56 Tarmac has a 395 reach + 100mm stem + 100mm bars = 565 total
So he swapped both the stems out for 90mm to try, which did help.

The 54s felt better reach in their stock configureations, though I was aware of the increased drop of the bars.
54 Emonda has a 381 reach + 90mm stem + 100mm bars = 571 total
54 Tarmac has a 384 reach + 100 stem + 70mm bars = 554 total
(54s also have 7mm less reach in the seat position as the angel is steaper.)

Measuring from floor to saddle & bars with a tape, with all spacers in place, I get the drop to be;
56 Emonda - 35mm
54 Emonda - 45mm
56 Tarmac - 60mm
54 Tarmac - 80mm

Overall, the 56s were definitly too long at stock. I seem to be more sensitive to the extra reach than I am to the increasing drop. Maybe its because of my short torso and long arms (+10cm on ape index).
Switching to 90mm made them very close to the 54s, but the smaller frame just felt slightly better still.

Does 80mm of drop sound like a lot for a new rider? It didn't feel bad, just low, on the 30 min test ride, but hitting a hill felt more comfortable / relaxed as the front was higher. Maybe experience is needed.

If I really wanted the best of both world, I could get the 56cm Emonda, and put a 70mm compact reach bar on it. But that isn't in the sale, so would be a be a big reduction in spec or increase in price.

[boyceuk]

My last post is pretty dull, so here a picture of my on the 54 Tarmac for you critique / laugh at.

I expect to see MTB helemt and white socks tucked in on the 2020 Tour de France!

[DaveS]

One thing to keep in mind is that reach can only be compared directly, when the stacks on the bikes are all the same. If one bike has 30mm of spacer, then the reach is reduced by about 9mm. When excessive reach is an issue, I recommend changing to 75-80mm reach bars, so a decent stem length can be maintained. If a drop of 80mm puts too much weight on you hands, it may mean that the saddle needs to be moved back a bit more. There are a lot of fitters who still use knee over pedal to set the saddle fore/aft position and that often is too far forward for a proper weight balance over the saddle.

I use Easton EC90 bars with an 80mm reach, so I can still use a 100-110mm stem.

[wheelsONfire]

I wouldn't buy any road bike frame using anything shorter than minimum 100mm.
If it's a very fast steering geometry, you'd want a longer reach (not frame, but stem + handlebar reach)
Flexibility seems overrated in terms of fit, it means less if your core strength is bad.

Btw, it looks like you could use a longer stem on that bike

[TobinHatesYou]

Does 80mm of drop sound like a lot for a new rider? It didn't feel bad, just low, on the 30 min test ride, but hitting a hill felt more comfortable / relaxed as the front was higher. Maybe experience is needed.

Your arms are almost locked out in the photo and you look tense with your shoulders rolled forward. You are also sitting very far back on the saddle and you have sneakers with immense midsoles.

IMO you should be sitting farther forward and you need about 2cm more frame stack. I'll go against the shop employee and say the 56cm is probably a better bike for you, but honestly you should be looking at an endurance frame.

I'm personally experimenting with raising my stack and just bending my elbows a lot more in both the hoods and drops.

[AnkitS]

I'm personally experimenting with raising my stack and just bending my elbows a lot more in both the hoods and drops.

Ahh that explains the boomer bars. Kinda.

[Jugi]

Does 80mm of drop sound like a lot for a new rider? It didn't feel bad, just low, on the 30 min test ride, but hitting a hill felt more comfortable / relaxed as the front was higher. Maybe experience is needed.

Your arms are almost locked out in the photo and you look tense with your shoulders rolled forward. You are also sitting very far back on the saddle and you have sneakers with immense midsoles.

IMO you should be sitting farther forward and you need about 2cm more frame stack. I'll go against the shop employee and say the 56cm is probably a better bike for you, but honestly you should be looking at an endurance frame.

I'm personally experimenting with raising my stack and just bending my elbows a lot more in both the hoods and drops.

As a static silhouette shot taken on the shop floor with toes on the ground, I think it's spot on.

[guadzilla]

Does 80mm of drop sound like a lot for a new rider? It didn't feel bad, just low, on the 30 min test ride, but hitting a hill felt more comfortable / relaxed as the front was higher. Maybe experience is needed.

Long legs generally come with long arms, so a larger drop is fairly normal. My saddle-to-bar drop is significantly more than yours and it isnt a crazy-aggro position.

Also, a tip - I find people with long legs may be better served by moving the saddle a little further forwards. All my bikes are set up with a zero-setback seatpost and slightly further of KoP-neutral positioning. This makes it easier for me to get my shoulders lower without closing off my hip angle too much - in fact, my road fit is actually halfway between a traditional road fit and a TT fit. Something to consider when setting your bike up.

[DaveS]

With my 168cm height and 83m cycling inseam, I always use a 25mm setback post. Most frames in my size have a 74-74.5 degree STA, so a setback post is a must. To use a zero setback post, I'd need about 2 degrees less STA.

Placing the saddle too far forward will put too much weight on your hands. A lot of fitters fix that by raising the bar height instead of moving the saddle back.