Do not listen to anybody saying you should learn it with the post up.+1 on. The sq lab bars. And don't cut them.
Help a roadie spec a climbing MTB!
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de lars cuevas
- Posts: 191
- Joined: Fri Jul 28, 2006 8:28 pm
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Whatever you do: buy a dropper, with a decent amount of travel (125 mm+). You say you're a terrible handler: you will love the added safety of the lowered seat on the descents, and it'll be way more FUN too! Do not listen to anybody saying you should learn it with the post up.
+1 on. The sq lab bars. And don't cut them.
Do not listen to anybody saying you should learn it with the post up.+1 on. The sq lab bars. And don't cut them.
Last edited by de lars cuevas on Sun Feb 20, 2022 7:21 pm, edited 3 times in total.
XC bikes used to have HTAs not too far from road bikes. I have a 2014 Felt 9 that I still commute on in winter - it has a 71deg HTA and it feels like a crit bike compared to my current mountain bike.
For modern XC bikes, I'd say 67.0 is progressive and 68.5 degrees is modern-normal. Slacker than 67.0 is more trail than racy and anything steeper than 68.5 is getting old-school.
The easiest advantage to understand for slacker HTA is that it puts the front wheel further out front (longer reach does the same), which means you can go down a steeper hill before you get to that 'uh oh' moment as you feel your weight shift around the front hub. All things (including reach) being equal, a 2deg slacker HTA means you can ride a 2deg steeper descent, with the same level of safety or sensation.
Longer wheelbase is a bit different, but if you've owned a Roubaix and Tarmac, you've already felt this a little bit. The difference between road bikes isn't too great (mms), but you'll likely have noticed the Roubaix is more stable and the Tarmac is a bit more eager to turn in. In mountain bikes, the wheelbase can be several cms longer (1100mm to 1160mm isn't an abnormal progression for a model over the last few years), so the difference is very notable.
The downsides can are that the front wheel can feel a bit floppy and steering a bit slower on low speed corners or climbs, but it's far easier to plan your climbing route, or recover from mistakes there, than it is on a downhill. As such, you'll see that longer and slacker has been accepted fairly universally for off-road riding - even drop bar gravel bikes.
For modern XC bikes, I'd say 67.0 is progressive and 68.5 degrees is modern-normal. Slacker than 67.0 is more trail than racy and anything steeper than 68.5 is getting old-school.
The easiest advantage to understand for slacker HTA is that it puts the front wheel further out front (longer reach does the same), which means you can go down a steeper hill before you get to that 'uh oh' moment as you feel your weight shift around the front hub. All things (including reach) being equal, a 2deg slacker HTA means you can ride a 2deg steeper descent, with the same level of safety or sensation.
Longer wheelbase is a bit different, but if you've owned a Roubaix and Tarmac, you've already felt this a little bit. The difference between road bikes isn't too great (mms), but you'll likely have noticed the Roubaix is more stable and the Tarmac is a bit more eager to turn in. In mountain bikes, the wheelbase can be several cms longer (1100mm to 1160mm isn't an abnormal progression for a model over the last few years), so the difference is very notable.
The downsides can are that the front wheel can feel a bit floppy and steering a bit slower on low speed corners or climbs, but it's far easier to plan your climbing route, or recover from mistakes there, than it is on a downhill. As such, you'll see that longer and slacker has been accepted fairly universally for off-road riding - even drop bar gravel bikes.
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FlatlandClimber
- Posts: 2491
- Joined: Tue Mar 31, 2020 3:37 pm
Thanks!
Cervelo P5 Disc (2021) 9.1kg
Factor Ostro Gravel (2023) 8.0kg
S-Works SL8 (2023) 6.3kg
*weights are race ready, size 58/L.
Sold: Venge, S5 Disc, Roubaix Team, Open WI.DE, Émonda, Shiv TT, Crux, Aethos, SL7
Factor Ostro Gravel (2023) 8.0kg
S-Works SL8 (2023) 6.3kg
*weights are race ready, size 58/L.
Sold: Venge, S5 Disc, Roubaix Team, Open WI.DE, Émonda, Shiv TT, Crux, Aethos, SL7
Don't buy a bike with crazy geometry in either direction.
68-69.5 is fin for a head angle.
73.5-74, maybe 74.5 if you have hsort femurs.
76 and 76+ seat angles are whack for an xc bike.
68-69.5 is fin for a head angle.
73.5-74, maybe 74.5 if you have hsort femurs.
76 and 76+ seat angles are whack for an xc bike.
FlatlandClimber wrote: ↑Sat Feb 19, 2022 12:59 pmHelp me out. I know what a head tube angle is and can imagine it lengthening or shortening the wheel base. But what is considered "progressive" and why? What is the advantage of a slacker hta?
Again, main focus is climbing. Handling skills are low.
One unexpected consequence of progressive/modern/LLS geometry is that bikes are HUGE (in length and width). I mean, I an from the 90s 71/73+26" era and a modern mountainbike (also due to larger wheels, but...) is a challenge to move around a cramped space, car, hallway and the like in comparison (especially considering that my bars have widened in average a centimeter per year!).
On the trail, though - unbelievable difference.
On the trail, though - unbelievable difference.
Too progressive or just right depend on your handling skill and your past experience.
A rider who trained on short sketchy bike will find some bike too progressive, like feel the bike to be too slack and less agile to change direction.
However, a new rider might appreciate progressive geometry more. Progressive geometry bike, sacrificing some handling agility, is more stable and if paired with a little more suspension (120mm rather than 100mm) can just plow through stuff that aggressive geometry 100mm have to ride around or hop over.
Cornering really tight on progressive geometry bike might require a bit more lean angle, which is easier to do if you can use dropper post to move seat out of the way.
Try to ride without a dropper post first. Getting used to mtb is already some work. Train to use dropper post effectively adds another complexity.
Soon, you'll know how to ride well without it. Then at that point, try one. Then you can decide if you need it or not.
A rider who trained on short sketchy bike will find some bike too progressive, like feel the bike to be too slack and less agile to change direction.
However, a new rider might appreciate progressive geometry more. Progressive geometry bike, sacrificing some handling agility, is more stable and if paired with a little more suspension (120mm rather than 100mm) can just plow through stuff that aggressive geometry 100mm have to ride around or hop over.
Cornering really tight on progressive geometry bike might require a bit more lean angle, which is easier to do if you can use dropper post to move seat out of the way.
Try to ride without a dropper post first. Getting used to mtb is already some work. Train to use dropper post effectively adds another complexity.
Soon, you'll know how to ride well without it. Then at that point, try one. Then you can decide if you need it or not.
75-76 degree STA are whack on any Hard tail bike but fine of full sus.
On full suspension bike, a bike started with 75 degree STA usually sag to below 74 degree STA under rider's weight. This is because bike usually is set with 15-20% sag front and 30% sag rear so rear sag more and make sta slacker in use.
On hard tail, without rear suspension, there's no rear sag. But front still sag 15-20% making STA even steeper than in geometry chart.
HTA change in another direction. Fork sag and make HTA steeper with rider weight. So, a longer fork that sag more is fine with slacker HTA. (Say, bike with 120mm travel fork can afford to be slacker than bike design with 100mm travel fork).
my version of progressive geometry explanation:
It's Long+ Low+ Slack+ Forward.
Long: bike gets longer on the top tube (and shorter stem). Wheel base gets longer.
Low: BB, headtube, (and fork offset) all are lower, increase stability.
Slack: Slacker HTA for stability.
Forward: Rider position is moved forward on the bike. Since your front wheel moved so much more forward. If the rider sit far back on top of rear wheel, you may have problem keeping front wheel straight while climbing steep stuff. So, the rider have to stand up a lot to keep traction on front wheel.
That's not ideal, so, progressive bike use steeper STA to move center of rider weight forward. Adding traction to front wheel when climbing seated. It also neutralize some length added to the top tube of progressive geometry. The downside is, sit more forward on the bike is less comfortable on flat terrain.
Look at the current Specialized Epic geometry. I'd say that is slightly progressive. Rocky Mountain Element is real progressive (for xc bike). And Canyon Lux is traditional.
It's Long+ Low+ Slack+ Forward.
Long: bike gets longer on the top tube (and shorter stem). Wheel base gets longer.
Low: BB, headtube, (and fork offset) all are lower, increase stability.
Slack: Slacker HTA for stability.
Forward: Rider position is moved forward on the bike. Since your front wheel moved so much more forward. If the rider sit far back on top of rear wheel, you may have problem keeping front wheel straight while climbing steep stuff. So, the rider have to stand up a lot to keep traction on front wheel.
That's not ideal, so, progressive bike use steeper STA to move center of rider weight forward. Adding traction to front wheel when climbing seated. It also neutralize some length added to the top tube of progressive geometry. The downside is, sit more forward on the bike is less comfortable on flat terrain.
Look at the current Specialized Epic geometry. I'd say that is slightly progressive. Rocky Mountain Element is real progressive (for xc bike). And Canyon Lux is traditional.
