tomato coupe

Read the thread.
1. The OP purchased a new frame.
2. Another poster noted on the difference between seat tube and head tube angles, and asked about the implications in regards to bike handling.
3. Two other posters and the OP then had a brief discussion about the angles and the handling characteristics.
4. The discussion wasn't about seat tube angle and seat post set back. It wasn't about trail. And, it most certainly wasn't about you and the details of the frames you own.

Shadco 

Very true.

On the other hand this thread has taken the direction so many other threads here do.

Frame selection was based on riding a number of other “endurance” road,and gravel bikes we have at our shop and comparing their specs to this one. Defy, Revolt, TCR, Crux, Roubaix, Tarmac, Impulso,Sprint,765 gravel, 765 Optimum +, and Huez.

This one will be quite different compared to my Roadie and gives me the chance to do a nice Campy build, probably my last one.

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tomato coupe

Say it ain't so ...

Shadco 

I tend to keep bikes a very long time, Raleigh International => Litespeed Arenberg => Gunnar Roadie ==> Look Optimum. Raleigh 25 years, Litespeed 4 years, Gunnar 18 years. Didn’t really care for the Litespeed. I’m 71 bikes have kept me healthy but there will come a point in time where…..

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PeteHski

HTA has a significant affect on handling. When I was considering this frame myself last year, it had by far the slackest HTA of any mainstream endurance road bike I could find. All the others were between 72.5 to 73.5 degrees from memory. I agree the relationship to STA is irrelevant. STA on this frame is pretty standard anyway. It's the slack HTA that stands out to me. That and massive tyre clearance.

Shadco 

So 34mm tire clearance is massive?

This isn’t the same frame as the gravel or plus variant.

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PeteHski

Yeah I see it has slightly different geometry. 765 Optimum+ and gravel have 0.5 deg slacker head angle.

PeteHski

Sorry yes I was thinking of the plus variant, which I very nearly bought last year.

Sy Reene

This is basically what I was wondering. If you arrive at the same trail for 2 different bikes that have differing HT angles, by simply changing fork rakes, would handling feel pretty much the same? Nonetheless, for a "road" (not gravel) bike, this Look seems to have a good amount of trail. I suspect this was done so they could tool every size frame with the same angles and only 1 fork choice, and the slack HT was needed for the XS frame to have tire clearance.

DaveSSS 

Having studied bike geometry for a long time, I look at the trail number and maybe the front-center if toe overlap is your concern. The 67mm trail is not overly large for the intended use of this frame. Some Italian brands don't even list the HTA or fork offset, considering their preferred dimensions a secret. I owned a 55cm Tommasini Sintesi back in the 90's that was that way. I still have a catalog of their offerings from that time. Colnago did the same. My current Cinelli Superstar has a 71 degree HTA with a 45mm fork offset that yields a trail of about 70mm, depending on the tire size. It handles great. My new Yoeleo frames have a 71.5 degree HTA and 43mm offset, that yields about 3mm less trail.
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I use the formula (R/tanH) - (offset/sinH) for trail. The first half of the equation is the trail without fork offset and the second half is the reduction in trail from the offset. The larger the tire diameter, the larger the trail. I've never seen a brand that listed a tire size.

PeteHski

The simple answer is no. They would have similar steering weight, but different front centre/wheelbase and castor. The slacker head angle would be generally more stable on descents. You can consider trail and head angle as 2 distinct parameters, despite their geometric link.

PeteHski

I presume this is a very small frame size i.e. XS. Medium is 72.5 for that frame and 73 in Large i.e. pretty standard angles. What Look have done here is keep the HTA under 71 deg across all their frame sizes. So for you it wouldn't make any difference to your norm, but would be a big difference for a taller rider. I'm 6'1" and nearly all bikes in my size have an HTA of around 73 deg, so the Look 765 really stood out for me as being significantly different - in a good way.

BTW my Canyon Endurace in size XS has exactly the same HTA and trail as your Cinelli, but it's quite different in my size L i.e. HTA 73 vs 71 deg, Trail 58 vs 70 mm. Handling is good, but it can be a little twitchy at times. My Giant Defy is slightly slacker at 72.5 deg with identical 58 mm trail (has about 6 mm more fork offset). My Defy is more stable descending even with such a relatively small difference. I would imagine the Look 765 is even better in this respect.

Sy Reene

Interesting convo. By way of comparison, and partly to blame for my curiosity, my bike has a 74d HT with 40mm rake fork, giving me about 56mm of trail (almost identical setup to a modern Emonda fwiw). I get that slacker HTs can enable more tire clearance for Endurance bikes, but is there really a link between trail/stability and the promise of 'all day comfort' or whatnot that is used to market "Endurance" bikes? I can't say for myself that there's a degree of 'twitchiness' that contributes in any way to making longer rides less comfortable.

DaveSSS 

The geometry of this frame is most different in the larger sizes, where the STA would usually be more slack. A seatpost with a lot of setback might be needed. The 74 degree angle is a bit steep, even in the medium size. A lot of smallest size frames have a 75 degree STA, which is steeper than I'd want, but I could use with a 32mm seatpost setback. I bought 32mm setback posts for my Cinelli Superstar frames, but it turned out that the STA was not the 75 degree listed on the geometry chart.

I ride an XS size in the Superstar, but most brands sell one size smaller. I've never bought the smallest size in other brand. My Yoeleo frames are a 47, which is the next to smallest. My LOOK 585s were size S, the next to smallest.

DaveSSS 

You need to qualify your remarks with a frame size. 56mm of trail is small, but not unheard of in the larger sizes. 58mm is thought by some to be magical for some reason, while the Italian brands favor more trail. The famous LOOK 585 had 58.2mm in all but the two smallest sizes. My size S had 64.4mm and the XS had 67.6mm.

Endurance bikes should have more trail so they're not twitchy at average speeds, but their main attribute is more stack height and shorter reach for a more upright position.

A common criticism of bikes with more trail is steering instability when climbing at 4-6mph. I've got no trouble with it. On fast descents, they're rock solid.
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DaveSSS 

Stick around. You might learn something, other than how to make rude remarks. There are a lot of of misconceptions about bike geometry. This particular frame is odd and not what I'd expect to see from LOOK. Riders needing the larger sizes may be disappointed if they don't understand the limited saddle setback with the 74 degree STA.

tomato coupe

Your remarks had nothing to do with what was being discussed. I simply pointed that out.

PeteHski

I think the difference between road "race" and "endurance" geometry is usually very subtle in regard to steering. This particular frame goes a little further than most, at least in medium sizes and above. I trawled through the geometry specs of most endurance bikes recently and the Look 765 really stood out for its slacker head angle, especially the plus version.

diphthong

love love my old 1995 look kg 131 carbon frame (classic flat top tube). enjoy! that frame looks fast!

Shadco 

Too bad the rider isn’t.

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diphthong

inspiration to keep moving! that's gotta account for something. beats the alternative...

Shadco 

And the fun begins.







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BTinNYC

Where's the muddy pooch?

Looking forward to the build.

Shadco 

This one?




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Shadco 

Some progress the saddle is a joke for a friend, spacer stack and stem are place keepers until the proper one arrives.

The Schwalbe Pro one’s were a ***** to mount.




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