Geometry/riding characteristics question

[macaroon]

I'm interested in a new frame, but I've looked at the geometry and the numbers concern me a bit.

My current bike has a 58 ETT, 74 head angle, 72.5 seat angle, 410 chainstay and a wheelbase of 1000, I use a 140mm stem. I like how it rides, it feels fairly spritely, rides like a road bike should, and goes downhill well.

The new bike I'm looking at has the same ETT and seat tube angle, but a 72 head, 420 chainstay, wheelbase of 1030 and a trail figure of 63.

I'm think the new frame might ride a bit like a barge? Is it correct to assume so? Especially with a long stem? I could use a shorter stem to quicken the handling, but my position would be more upright and Im not sure it'd be as comfy. It'd also be less good for out of the saddle climbs with a shorter stem aswell.

Anyone got any input with regards to the above? Do any of you own a slack angled bike? How does it ride?

[CMiller]

The numbers are not too different, I wouldn't even call the new frame slack angled, to me those are aggressive angles.

I think that you will notice a more stable descent on the new frame with the longer chainstay and slightly slacker headtube, all other factors equal. I believe, however, that the material differences could have an even bigger effect on a frame.

If anything, it might be nice to have a super quick handling bike and another more stable ride in the garage, pick a bike that suits the terrain. Good luck and have fun!

[Peter P.]

If you like truly like the way your current bike rides, then the prospective bike you're looking at will feel quite different.

I'm not sure "barge" is the correct term. It'll certainly hold a straight line with little input from you. It just won't have the "spritely" manners you've grown accustomed to. Most people would classify this frame as one of those "endurance" geometry frames. It could also be considered a sport touring design.

Sounds like this frame also has a 43mm rake fork. The manufacturer probably uses the same fork throughout the size range to keep SKUs down.

My bike has a 72 degree head angle with a 50mm rake fork (and 42cm chainstays). It's definitely a more "calm" steering than my old bike's 73/45 setup, but you could consider it "certified" for a race bike because the same geometry is used by Independent Fabrications on their old, stock size, geometry charts for a similar size frame. I couldn't see putting a 43mm rake fork on my frame. At that point the bike would definitely have too much trail for my liking.

This new frame candidate can certainly do duties for training, group rides, and racing. It'll just handle differently. However, since the numbers concern you, you would be better off avoiding it unless you can demo a bike first.

[pbarry]

I'm interested in a new frame, but I've looked at the geometry and the numbers concern me a bit.

My current bike has a 58 ETT, 74 head angle, 72.5 seat angle, 410 chainstay and a wheelbase of 1000, I use a 140mm stem. I like how it rides, it feels fairly spritely, rides like a road bike should, and goes downhill well.

The new bike I'm looking at has the same ETT and seat tube angle, but a 72 head, 420 chainstay, wheelbase of 1030 and a trail figure of 63.

I'm think the new frame might ride a bit like a barge? Is it correct to assume so? Especially with a long stem? I could use a shorter stem to quicken the handling, but my position would be more upright and Im not sure it'd be as comfy. It'd also be less good for out of the saddle climbs with a shorter stem aswell.

Anyone got any input with regards to the above? Do any of you own a slack angled bike? How does it ride?

Are you positive on the STA and HTA numbers? Looks like they are reversed.

[macaroon]

Are you positive on the STA and HTA numbers? Looks like they are reversed.

Hi, yes, the geometry I posted is correct.

Good points above, perhaps a test would be in order so I don't make an expensive mistake.

I've had a bike with a slack head angle before; I wasnt so convinced. I thought it'd be good downhill, but I perhaps felt that I didnt have enough weight over the front wheel?

I thought head angles generally steepen as the frame sizes increase? I'm assuming because taller riders tend to use a longer stem.

[pbarry]

Got it, old vs. New. :)

[macaroon]

:banana:

[carpediemracing]

I think the second bike will feel slower, esp out of the saddle.

My current bike has 393mm stays. I spec'ed it with 405mm stays. I got a second frame with 390mm stays due to issues with the rear wheel skittering in turns with the first frame. It worked so well I asked the builder to shorten the stays on the first bike.

Although front end was totally unchanged the bike felt absolutely and fantastically different. No real difference seated, except the rear wheel didn't skitter in turns, but out of the saddle it felt like I was riding a unicycle. It would go wherever I wanted it to go. The best.

Both my bikes have long wheelbases due to the longer ETT (565m, on effectively a size S or 50-52 cm frame). Both have 73 HTA with 43mm rake, a copy of my favorite front end bike my old Cannondale.

I can't comment on HTA, trail, etc, because I haven't had any A-B type experiences with that, but for the chainstay, I think the 1 cm longer stays will make the bike feel much more stable or much slower, depending on how you view it.

[pbarry]

The old rule of thumb of 1000mm for wheel base is long gone. Most big cos have thrown that out. Wheel base, no matter the frame size, has been greatly expanded over the last 20 years.

The new frame's slacker HTA, and resulting trail with it's stock fork, will feel like a dawg to you on the first outing. All depends on how you ride if it will matter in a few miles of getting used to it. The trail number is too high if you mainly ride road IMO. Cross or gravel? On the money.

I T-boned a taxi in NYC when I was a messenger. The cab swung across two lanes on Broadway to make a left into my path. My HTA went from 73 to 76 or so, and rake went from 43 to 38, perfect trail! The bike handled like a Porsche on EPO for the two weeks before it failed..

[Peter P.]

I thought head angles generally steepen as the frame sizes increase? I'm assuming because taller riders tend to use a longer stem.

The main reason frames steepen the head angle as frame size goes up is an attempt to keep the wheelbase or front-center within some preconceived number, which appears to be as close to 1000mm as possible.

You would think they'd just build the top tube as long as necessary then add the head angle to the desired ride quality of the frame and just ignore wheelbase. It's as if they want a 60cm frame to corner in the same radius as a 50cm frame.

[Scooper]

OK, I'll admit I'm an older (72) rider and am endurance oriented rather than racing oriented; comfort and stability trump twisting myself into a pretzel and getting fatigued/exhausted on a long ride because of squirrely handling.

The custom 61cm c-t Waterford RS-22 I ride 95% of the time has a 72.5° STA, 73° HTA, 432mm chainstays, 1031mm wheelbase, 75mm BB drop, 42mm fork offset, and 59mm trail.

This bike is stable and comfortable on week long 550 mile rides, and handling is tame but not sluggish at all. It's great on fast descents.

It's a refreshing change from the crit geo bikes I used to ride.

http://i32.photobucket.com/albums/d7/k4drd/Bicycles/Waterford%20B07014/WaterfordRS-22B07014PhotoandDwg_zps6f3d4774.jpg

[Ken Robb]

OK, I'll admit I'm an older (72) rider and am endurance oriented rather than racing oriented; comfort and stability trump twisting myself into a pretzel and getting fatigued/exhausted on a long ride because of squirrely handling.

The custom 61cm c-t Waterford RS-22 I ride 95% of the time has a 72.5° STA, 73° HTA, 432mm chainstays, 1031mm wheelbase, 75mm BB drop, 42mm fork offset, and 59mm trail.

This bike is stable and comfortable on week long 550 mile rides, and handling is tame but not sluggish at all. It's great on fast descents.

It's a refreshing change from the crit geo bikes I used to ride.

http://i32.photobucket.com/albums/d7/k4drd/Bicycles/Waterford%20B07014/WaterfordRS-22B07014PhotoandDwg_zps6f3d4774.jpg
Hey Thompson! This is "just our size".

[tigoat]

It seems like we are so fixated strictly with geometry when it comes to define handling of a bicycle while there are so many other factors involved. The rigidity of your fork, handlebars, stem, wheels, tightness of bearings, etc. can all contribute greatly to the handling of a bike. As long as you are in the acceptable range of angles, the geometry should not matter that much in terms of handling, mostly a subjective thing in your head to diagnose. The human body is amazingly flexible and can be easily programmed to adapt to small changes in handling.

[macaroon]

Brilliant, some more food for thought. I think Im being swayed away from this frame at the moment; most of my riding is between 1 and 3 hours, so "endurance" geometry perhaps doesnt make sense for me?

I once owned a Surly Cross Check; my first ride out, I stood up to climb a hill (something I do alot of) and I remember thinking how unresponsive it felt. Very slow/sluggish. I think the stays were 425mm and the headangle probably somewhere around the 72 degree mark (not sure what the fork rake was).