For the geometry experts...

[Daverino]

I've come across the opportunity to buy someone else's custom seven steel frame. It's got the TT measurement that works for me, but the front geometry I can't get my mind around. I'm not a racer, but like to push myself in the occasional group ride. I prefer climbing (and descending) and going for long rides. My current bike (whose ride qualities I really like) is a Specialized Roubaix. Here are the Seven's specs:

TT: 535mm
HT: 145mm
STA: 74
HTA: 71.25
Fork Rake: 50mm
Trail: 62.5mm
Wheelbase: 1000mm

I'm guessing that this is a fairly slack HTA, which I don't mind. The bike is not available for me to test (too far away), but I'm tempted to make the plunge. My questions is: Any further opinions on how something like this will ride?

[Marcusaurelius]

I seem to remeber colnago steel frames have a slack head angle and they are known to be a great riding bike. I rode a friend's and it felt good even if it was a little small for me.

[cmg]

tall head tube for a frame with a 53.5 tt. is the seat tube a short one? 49-51? usually head tube length is around 100mm.

[regularguy412]

tall head tube for a frame with a 53.5 tt. is the seat tube a short one? 49-51? usually head tube length is around 100mm.

My thot, too.

How do the numbers compare to your Roubaix? My riding buddy has an '05 Roubaix and the front end seems tall-ish. That is, the front end is taller, relatively speaking, compared to his ~90 model Serotta NHX. If it's any consolation, he's riding the NHX exclusively now.

Mike in AR:beer:

[pdmtong]

roubaix has slack HTA and longer rake to compensate. this may be similar.

[Peter B]

My guess is the TT slopes at least 4* to get that HT length. You should be able to get from a nearly level saddle to bar relationship to decent bar drop unless you have very short legs or are looking for >3" drop. The trail number indicates a bike with stable handling. Should be smooth and confidence inspiring rather than a twitchy crit or track frame. Remember that the 74* angle will make that TT seem a bit longer for a given setback than a 73. Figure a cm per degree and calculate relative difference based on the STA of your Roubaix.

Peter

[Ken Robb]

[
Remember that the 74* angle will make that TT seem a bit longer for a given setback than a 73. Figure a cm per degree and calculate relative difference based on the STA of your Roubaix.

Peter[/QUOTE]

Isn't it the other way round= slacker st angles=longer top tubes?

[Peter B]

For the sake of discussion let's assume TT is measured CC. Consider as a baseline a 73* STA and 53.5 TT w/ a 6cm setback (saddle tip to BB). The tip of the saddle is now known as a point in space. Increase the STA to 74*. If you do nothing else, the tip of the saddle is now pushed ~ 1cm further forward in space (do the trig). So is the HT (the TT stays constant at 53.5, right?) In order to maintain the original 6cm saddle setback relative to the BB we'd now have to move the saddle back the same ~ 1cm. But since the TT is a constant at 53.5, and the HT was pushed ~1cm further forward, TT has now effectively grown by the same ~1cm to 54.5.

Peter

[ThirtyEast]

It looks to me like Seven was trying to build this bike with the elimination of toe overlap as their primary focus. That's the only reason to have such an extremely slack head angle with that fork. It's not going to handle like a Colnago because the fork rake is so different. This bike is going to steer quickly but turn slowly, if that makes any sense. In other words, because of it's wheelbase, which is considerable, it's turning radius will be very large, but small inputs to the handlebars will result in the bike deviating from center. Not twitchy, but a little quick with the inputs.

[Daverino]

My thot, too.

How do the numbers compare to your Roubaix? My riding buddy has an '05 Roubaix and the front end seems tall-ish. That is, the front end is taller, relatively speaking, compared to his ~90 model Serotta NHX. If it's any consolation, he's riding the NHX exclusively now.

Mike in AR:beer:

The numbers are quite close. I was riding a 54cm Roubaix which has:

TT: 548mm
HT: 165mm
STA: 73.5
HTA: 72
Fork Rake: 49
Wheelbase: 1000mm
No details on the website re trail, which I suppose could be calculated.

Here are the Seven's specs:

TT: 535mm
HT: 145mm
STA: 74
HTA: 71.25
Fork Rake: 50mm
Trail: 62.5mm
Wheelbase: 1000mm

New info: the ST length on the Seven is 48.2.

I think I'll make the purchase. In the 4 years I've had my Roubaix, my only complaint is that I feel a little stretched out in the cockpit. This new frame might be exactly what I'm looking for. T

Thanks for everyone's input!

[Daverino]

This bike is going to steer quickly but turn slowly, if that makes any sense. In other words, because of it's wheelbase, which is considerable, it's turning radius will be very large, but small inputs to the handlebars will result in the bike deviating from center. Not twitchy, but a little quick with the inputs.

You are describing my Roubaix perfectly! This actually helps me confirm that the Seven is probably for me. Thanks.

[cmg]

please post a photo of the seven when you complete the build. it would be interesting to see how close both are in geometry.