MTB geometry

JHZR2

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Need a bit of schooling on MTB geometry. Want to start getting into it more with my oldest, and back to riding more with some of my friends. I went from a 2000 KHS Alite 26”, to a Scott Scale 29er (2012-ish). I really like the Scott, I test rode a good number of 29er bikes and found it to be the most nimble and enjoyable to ride. I kind of have the itch for a more aggressive MTB, and caught my eye on the Jamis Dragon.


While I like light bikes for putting them easily on a bike rack on a vehicle, for all intents and purposes I don’t think a bit of weight from a steel frame matters much. I do notice a bit of flex in my Scott Scale, and I feel like I’d like to try a steel bike since I have a light aluminum bike.

But the geometry seems different, the bike seems long…they say that, “We’ve been designing and building Dragons since 1993, but this latest version is an entirely new beast. Slacker front end and longer top tube means more room to get rowdy…with the buttery smooth ride our steel Dragon is legendary for. Say hello to your new favorite hardtail.”

I don’t really understand MTB geometry much, never have really looked into it. What does the slacker front end and longer top tube mean practically speaking? How does it help me climbing in loose soil and rocks? I would like a bike that I can climb steeper terrain in conditions with loose soil, rocks, and lots of roots.
 
this explains it better than I can. FWIW I like my "old school" geometry bike better than my newer one, but I am happy on both

 
I have been out of hard core bike riding for decades but,, weight is the enemy and with geometry, you have to ride it to see if it works for you.. .
 
This
I have been out of hard core bike riding for decades but,, weight is the enemy and with geometry, you have to ride it to see if it works for you.. .
You can't depend on someone telling you a bike looks slack or not. And the labels for MTB bike types, I have found grossly everlap. Downhill to enduro to trail.........

YES frame geometry is important, but it must be way way more important for folks who push limits. Seems like to me - for most riders who do all all sorts of riding (from pavement to trails to downhill to climbing) - the ability to quickly change as needed seems key.

I find the fact that I dial my suspension in on the fly near the top of changeable things, (of course gearing is always top) but a dropper post is right up there. I can turn my shocks (all three) OFF with the flick of two switches or full dampening with some sag if I like. My carbon "downhill" bike really isn't. It rides great everywhere. Oh it's happy pointed down some scary stuff and that's a great thing, but turn the rear shock off, put the fronts at ~ 25% and it climbs fine, put them both at 0-25% and street is great. Full on? Flat or downhill crazy trails with ease.

Yet even with my heaviest seat (I have 3) and winter fenders, my bike is light enough for me.
 
The biggest issue with new bikes is finding one. There's a serious supply problem that isn't going to resolve in the near future. That Jamis is a good bike but can you find one to buy?

I've been riding mtbs since '88 and have usually stepped up every few years to stay current. I sold a 2016 Devinci 27.5x3.0 full suspension bike in July of 2020 thinking I'd replace it with a 2021 hardtail in the fall in the meantime I'd ride my 2000 Litespeed hardtail. The Litespeed was a pretty good bike BITD and I rode it hard and fast. The current geo was 71 deg head tube and 72 deg seat tube, 110 mm +/- stem, 26 inch wheels, 80mm fork. Going from the Devinci to the Litespeed was a shocker, the Devinci was at the beginning of the new normal geo, longer and slacker so the Litespeed felt like I was sitting high and way over the front tire. I had to back off and walk some downhill bits that were no problem on the Devinci and tech uphills took a lot more concentration. Current geo on "trail" hardtails is 65/66 deg head tube, 74/75 deg seat tube, a longish top tube and a short 40ish mm stem. It feels funny, the front tire feels way out in front of you like a chopper. I really wanted a Salsa Timberjack but they were not to be had until April of this year so after much searching finally found a 2021 Specialized Fuse Expert that I drove 100 miles to Phoenix to buy. I can say without a doubt this is the most fun to ride mountain bike I've ever owned. It's kinda heavy with the 29x2.6 tires and beefy 130mm fork but it's so stable on chunky downhills and turns well and surprisingly climbs well I don't care about the weight. I'm at a stage where I don't care about going FAST but I want to ride well and feel safe doing it. I got the bike last October and have over 2000 miles on it now and still love riding it 50-60 miles a week on fun trails.

I would have bought a Dragon but there were none to be had. It has a build spec close to my bike and weighs the same. It's not going to be as nimble and flicky and light as the Scale but it would be a hoot to ride. I was skeptical about the 1x12 drivetrain and dropper and 29x2.6 tires but they all work. If you want to go fast all the time a "cross country" bike that's lighter and less slack with 29x2.2 tires might be better.

Hope that helps. Watch the review video that's linked on the Jamis website by the Hardtail Party guy.
 
It's about your body positioning on the frame. So, a little more of your weight will be over the bars, helping your climbing while seated. But tires (size and tread design) along with air pressure will also greatly influence the grip on loose soil, rocks and roots.
 
I don’t really understand MTB geometry much, never have really looked into it. What does the slacker front end and longer top tube mean practically speaking? How does it help me climbing in loose soil and rocks? I would like a bike that I can climb steeper terrain in conditions with loose soil, rocks, and lots of roots.

Wait, didn't you recently get a new bike?

Anyway, being able to climb steep with loose dirt rocks and roots takes some good technique and strength as well as good equipment. IMHO The best bike you could buy for those conditions would be full suspension with wide tires like 2.8s or 3.0s. Next would be a hardtail with the wide tires. The longer wheelbase helps keep the front end down and gives you a wider range to shift your weight to keep traction. The slack front end on these trail bikes is good for stability and going down steeps with rocks roots etc, the downside is on slow steep climbing they want to flop a bit side to side and you have to get used to that. I noticed it at first but got used to it and it's not a problem. Depending on your terrain and how you want to ride 27.5x 2.8 tires might be worth a look as well as 29 x 2.4-2.6 size. Some bike brands have the same bike with either size tires. The full suspension Devinci had 27.5 x 3.0s and it would climb steep rough stuff I didn't think I could ever get up.

A friend came here to ride and brought a Specialized carbon Epic hardtail with more conservative cross country geo and we traded for a 25 mile ride one day. It was definitely faster on smoother trails and was obviously lighter but in rock gardens and steep downs I really had to back down compared to my bike. He had a blast on mine.
 
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I don’t really understand MTB geometry much, never have really looked into it. What does the slacker front end and longer top tube mean practically speaking? How does it help me climbing in loose soil and rocks? I would like a bike that I can climb steeper terrain in conditions with loose soil, rocks, and lots of roots.
For climbing steep rough terrain, you need traction. The most important thing will be the right kind of tire, and tubeless so you can run low pressures for even better traction. If you run tubed tires at the low pressures that give great traction, you'll get flats. The next most important things for climbing will be frame efficiency and light weight. IME, frame geometry is also helpful as it can get your body in a position that has better leverage for your pedaling, but for climbing it's not as important as those first factors. Where frame geometry makes the biggest difference is on the downhills; it determines how responsive the bike is. This is subjective. One man's "stable/solid" is another man's "slow/unresponsive", and one man's "responsive" is another man's "twitchy". Of course, as a conventional front suspension compresses, the head angle gets steeper/more aggressive which you can definitely feel.
 
Here's a good comparison of contemporary frame geometry and parts then vs now. 2021 Specialized Fuse and 2000 Litespeed Pisgah. The Litespeed has a swept riser bar otherwise the bars would be lower than the saddle.
fuse&LS.jpg
 
Wait, didn't you recently get a new bike?

Anyway, being able to climb steep with loose dirt rocks and roots takes some good technique and strength as well as good equipment. IMHO The best bike you could buy for those conditions would be full suspension with wide tires like 2.8s or 3.0s. Next would be a hardtail with the wide tires. The longer wheelbase helps keep the front end down and gives you a wider range to shift your weight to keep traction. The slack front end on these trail bikes is good for stability and going down steeps with rocks roots etc, the downside is on slow steep climbing they want to flop a bit side to side and you have to get used to that. I noticed it at first but got used to it and it's not a problem. Depending on your terrain and how you want to ride 27.5x 2.8 tires might be worth a look as well as 29 x 2.4-2.6 size. Some bike brands have the same bike with either size tires. The full suspension Devinci had 27.5 x 3.0s and it would climb steep rough stuff I didn't think I could ever get up.

A friend came here to ride and brought a Specialized carbon Epic hardtail with more conservative cross country geo and we traded for a 25 mile ride one day. It was definitely faster on smoother trails and was obviously lighter but in rock gardens and steep downs I really had to back down compared to my bike. He had a blast on mine.
Yeah, a grocery getter and tool around town getting ice cream and going to the park with the kids bike… a trek verve. Totally different reason - my wife is pregnant, amd we were both looking for something a bit more comfortable than our mtbs for just going on the boardwalk, rail trails and the surface streets around town.

I do have a specialized road bike that I haven’t used in years (might convert to a gravel bike), and my Scott scale, which I love but seems to have a tiny bit of flex in some conditions. So whether I keep the Scott, or not, I’m generally interested in a decent mtb, since my oldest is interested in getting into it. I want something that I can build skill on, does well climbing in dirt, and thst is comfortable enough, for other conditions.

Because I’m no racer, and have I guess excess weight (both fat and muscle), I think I’ll be better served loosing a few pounds, over fretting over bike weight. It seems like a steel bike would be good for my 6’4, 250ish mass.
 
Yeah, a couple of pounds on a bike isn't going to be a big deal. You're probably looking at XL frames, something to think about is that steel is known to be a softer ride usually than aluminum, meaning more flex. You're a big guy, you may feel some flex in that steel Dragon. The Scale bikes were always thought to be lightweight in the class so it's not surprising that you feel some flex. A softer ride isn't a bad thing unless you get tire rub or ghost shifting from too much flex. Good luck.

This guy does a pretty good job reviewing hardtails. He does have his idea about what he wants in a bike but what I like is he compares how this rides and handles versus other bikes he's tested.
 
To help answer your question about geometry and climbing (technical climbing). A slacker bike, a longer seat tube and a longer bike will definitely climb BETTER. Much better. Your front tire won’t lift nearly as much compared to a less slack head tube angle. The overall reach of the bike to handle bars to where you sit (longer bike might help), also won’t allow to lift that front wheel as easily. I higher seat tube angle will keep you waited/centered/balanced. The bike won’t easily wander as much. The steering will stay more in line of where you want to pint the bike and go, which is HUGE in technical steep climbs. It really is.

And as far as going down the other side of that hill, a slacker front will make the bike feel more stable.

And as far as length of the bike, I prefer a longer bike. It feels more stable to me. I find them to be better for technical choppy rides where my front tire encounters something and I need my rear tire to not encounter the same thing (because I need to dig myself out of it, or avoid it entirely).

The downside is that sometimes these types of bikes are not as flickable and fun. Sometimes they arent easy to do drops and jumps with. Wheelies with, not a lot of fun. Unless you’re a very good rider with those types of things, but I prefer being able to climb like a billy goat. I love chunky, choppy, technical mountain biking. I love difficult climbs and all the trash I have to ride through, around, up and over. That’s my thing. I love that stuff. I’m not a downhill, table top, 5 foot drop, type of guy. And just by the looks of it, the Jaimis Dragon would fit me to a T...but it’s hard tail so I’m out. Too old for that pain. Haha.
 
Wide bars..like 750mm or longer go along with those slack angles.

So many years ago when I started riding steep angles with 520mm bars were the norm on the converted road bikes.

I like slack with wide bars with the 26 and 29 wheels.
 
I remember the last 80s when mountain biking was still fairly new. Modern mountain biking really comes from riding Marin Water District trails in the 70s. They had to improvise with what they had, but eventually they started making purpose-built mountain bikes, starting with Gary Fisher working with Tom Ritchey.

Back then I remember the talk was that a smaller, tighter frame than a suitable road frame would be suitable. I rode a 57-58 cm (22.5-23") road bike. but I was told that a 17-18" mountain bike with a long seatpost and shorter wheelbase would be more manueverable. However, my first mountain bike was used more for my college commute, and that was 19", although I did take it on trails a few times.
 
The longer wheelbase and slacker headtube bikes really help on descending on the steep stuff. You'll be able to roll down stuff that you probably wouldn't try on your old bikes. High speed stability is better too. For me, while I still ride my old mtb, the replacement will have much more reach and wheelbase.
 
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