New Bike Geometry-

[Mikej]

If you were building a custom ti disc road bike, for 99% road riding, in about a size 58, what would or have you done for chain stay, head tube angle and rake? I’ve been suggested a 72 degree HTA with a 50mm fork for comfort, which I asked for, but as an additional option vs a more traditional 73 HTA with a 43mm fork. I plan to mainly run 25’s or 28’s, but frame and fork are built to handle 32’s. Just inquiring as to others experience, I’m leaning to the 73. I know it’s vague, but thanks for any input.

[tuscanyswe]

I like steep hta in general so would not go lower than 73 unless a builder could persuade me with reasons i had not thought of.

72 for increased comfort when allrdy riding 28 or even 32s? Im not saying its wrong just would not be a a concearn for me.

[prototoast]

72/50 is a good combo for 35+mm tires for increased tire clearance. For 32mm and under, I would go with 73/43 personally, or even potentially 73.5/43 if you like something a little faster responding (73.5/43 with a 32 tire will match pretty closely 73/43 with a 23 tire).

As for chainstay length, I would go with whatever you normally like riding. Personally I like 410-415 chainstays with an 80mm bottom bracket drop.

[John H.]

Need more info-
1.) is toptube 58? (some name the size by the seat tube length- then it could have anything for tt length).
2.) Stem length?
3.) Saddle to bar drop?
4.) How much saddle setback?

[Peter P.]

If all you've been familiar with are the steeper head angles of previous frames and you have gotten tired of them, then definitely go slacker on the HTA.

But, given the usual HTA on frames your size (73.5 or 74), going to a 72 will be somewhat of a shock. I recommend a 72.5/45 combination. It tames the steering yet it's still perfectly maneuverable, and not flustered by crosswinds.

I have both 72.5/45 and 72/50 on bikes I own. I prefer the 72.5 combo, and if I were to do it again I'd pair the 72 with a 53-55mm fork rake. The 50mm is probably better for gravel riding for stability, and I just haven't adjusted my handling skills to accommodate the combo for road riding, even though there's really nothing wrong with it.

FYI: Independent Fabrications specs a 72/50mm pairing on their older, stock Crown Jewels so it's a perfectly legit setup.

That road bike above with the 72/50mm combination has 42cm chainstays, and fits 32mm tires but you may watch the BB drop otherwise you'll have to squeeze the tire against the seat tube to fit it in the dropouts. Your frame builder will be able to verify.

[72gmc]

I have a bike built for the tire sizes you've listed. It's 73 degrees for head tube and seat tube and stable as can be. Doesn't phase it to add a nitto rack, wald basket, and commuting bag, and it doesn't steer like a truck when I take the rack off. I don't know the chainstay length but it's probably 430 or less, 61x59 main tubes.

[OtayBW]

If it's to be dedicated to road riding, you might like a little more trail (slacker HTA). :hello:

[teleguy57]

My ti Alliance disc (https://forums.thepaceline.net/showthread.php?t=233087&highlight=alliance+disc)(saddle to bar reach 57.8, saddle height 76.6) has a 72.3 HTA with a 47mm rake for trail of 60. Love it.

But the real answer is "what the builder you've selected recommends."

[David Kirk]

what are the -

seat angle?

top tube length?

stem length?

color?


dave

[colker]

what are the -

seat angle?

top tube length?

stem length?

color?


dave

All i care is yellow and white is the best color combo for my riding. Other than that, chose a good builder.

[Mikej]

I didn’t think seat tube length was relevant to geometry so I thought you guys would take the 58 as a top tube. It’s centimeters btw. 73 sta 7.2 drop 41.8 cs. 18 ht. 120 stem at 92.5. 8.3 set back. 78.3 saddle. I see a lot of the full gravel type bike with the 72 / 50. I wanted an Enve fork, so 43 it is. Thanks for the input everyone- now for decal color....not sure about the down tube. To be honest, I started leaning towards qr, non electronic, rim. I don’t need to be anymore complicated.

[Mark McM]

If it's to be dedicated to road riding, you might like a little more trail (slacker HTA). :hello:

There seems to be 2 schools of thought on this. Some say that road bikes should have slacker angles/more trail than off-road bikes because they travel at higher speeds. Others say that off-road bikes should have slacker angles/more trail because they are ridden on rougher terrain. Looking at the range of angles/trails used on most bikes these days, off-road bikes (i.e. MTBs) are the ones with slacker head angles/more trail.

From my personal experience, I find that a slack angle/long trail MTB ridden on the road feels too stable/non-responsive (even with narrow tires), whereas a steeper angle/shorter trail bike feels unstable/twitchy when ridden on trails (even with fat tires). So my preference is steeper head angle/shorter trail on road bikes.

[OtayBW]

From my personal experience, I find that a slack angle/long trail MTB ridden on the road feels too stable/non-responsive (even with narrow tires), whereas a steeper angle/shorter trail bike feels unstable/twitchy when ridden on trails (even with fat tires). So my preference is steeper head angle/shorter trail on road bikes.
I know. You've mentioned this. I have both 'normal' (~56-58 mm) trail bikes and one old Italian steel with trail closer to ~65 mm that handles great for me. All are in my rotation. YMMV.

[commonguy001]

Not a disc bike but-
When I first switched from the older Vamoots Geo to the newer version it was a bit of a shock. I had become very accustom to the handling and feel of the 74 HTA with 40-43mm rake fork and LOVED it.
The newish 58cm Vamoots I have has a 72.75 HTA and I'm running it with a 45mm rake fork. It was not love at first ride, far from it. What I'll say is after a month or so I completely forgot about the differences and have come to love the stability of the bike running tires that measure out to just under 28mm.

Granted there are a heck of a lot more to it than HTA but whoever they did with my 14 Vamoots really works well for me and continues to after 4 years of owning it. Cheers to Campy Man on here for parting with it (I still love it!).

[Mikej]

Not a disc bike but-
When I first switched from the older Vamoots Geo to the newer version it was a bit of a shock. I had become very accustom to the handling and feel of the 74 HTA with 40-43mm rake fork and LOVED it.
The newish 58cm Vamoots I have has a 72.75 HTA and I'm running it with a 45mm rake fork. It was not love at first ride, far from it. What I'll say is after a month or so I completely forgot about the differences and have come to love the stability of the bike running tires that measure out to just under 28mm.

Granted there are a heck of a lot more to it than HTA but whoever they did with my 14 Vamoots really works well for me and continues to after 4 years of owning it. Cheers to Campy Man on here for parting with it (I still love it!).

Thanks for this-

I’m looking at a 59 with 28’s