Modern Mountain Bike Geometry By Transition Bikes
Bike geometry can be complicated. It's nearly impossible to know everything about how a bike will ride based on looking at these numbers alone (not to mention these numbers tell you nothing about how the suspension itself will function). But we hear it being done all too often - and to be fair, we do it too. Problems arise when riders focus on just a few of these numbers instead of how they all relate to one another.
There are no right answers here. We're opinionated about this stuff and we'll let you know it. In the end, there are preferences and our hope is that this article provides the grounds for a more informed discussion of bike geometry. We're going to keep it pretty basic, and some of you might find a lot of the topic a little too 101. But we frequently come across pretty educated riders who haven't fully considered some of this stuff. Even in the basics you might come across a few new ideas. We hope it makes you think more about all of the details in your bikes geometry - we think about it a lot.
We'll begin with a topic that we see people confused about all the time....
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Effective Top Tube (ETT) is a traditional way to measure a bikes length. It measures a horizontal line, parallel to the ground, from the center of the head tube to the intersection with the seat tube or seat post. This number is useful for identifying how long a bike will feel while in a seated position.
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Reach is newer way to measure a bikes length. It uses the same horizontal line as the Effective Top Tube, but instead of measuring from the head tube to the seat post, it measures from the head tube to a vertical line that runs perpendicular through the center of the bottom bracket shell to the ground. This measurement identifies how long a bike will feel while standing.
So Reach measures your cockpit anytime you're standing and Effective Top Tube measures your cockpit only while seated with your saddle at a specific height. They're both telling numbers and it's worth considering them together, but we put a lot of emphasis on Reach these days. Any time we're riding aggressively, we're out of the saddle, so it follows that this number is going to have a greater overall impact on the "handling" characteristics that define the modern trail or all mountain rider.
One of the most common problems we see is over-emphasis on Effective Top Tube length. As a whole, bikes tend to be getting longer front ends these days. But that can be done with a longer ETT, a longer reach, or a combination of both. Riders who look only at Effective Top Tube without considering reach may be selling themselves short, literally. That's because seat angle has a huge effect on ETT, but zero effect on Reach. Watch what happens when we make the seat angle slacker:
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The Effective Top Tube is now longer, but the Reach has remained the same. Or to look at that in another way, it's not hard to imagine a scenario where the Effective Top Tube of 'Bike A' is the same as 'Bike B', but the Reach of 'Bike A' is actually shorter than 'Bike B' because 'Bike A' has a slacker seat angle. This happens; a lot. In these cases, Bike A may fit great while seated, but while standing, the cockpit length is too short and the rider doesn't have enough room to move around or find the bikes sweet spot.
The slack seat angle that afforded the rider adequate seated top tube length does nothing to help the rider move around on the bike while in a standing position. It has other effects as well. The riders seated weight will be further over the bikes rear axle, making the rider work harder to keep the front wheel on the ground while climbing and harder to effectively transfer power to the cranks. The taller the rider/seat post, the more dramatic this effect will be because the seat itself keeps moving rearward as the saddle height is raised. So rather than slacken the seat angle to increase a bikes Effective Top Tube, why not increase the Reach? Proper position while seated and standing.
Another problem with ETT as a whole is that, because it's influenced by seat angle, the actual feel that a listed ETT provides will vary from one rider to the next depending on how high they run their saddle, even on the same frame. Reach is more constant. Consider a rider who is 6' with two bikes; both bikes have a listed ETT of 610mm, but they have different seat angles. ETT is always measured in a parallel line to the ground starting at the top of the head tube. Now let's assume this riders actual seat height is 5" above where the ETT is measured. The bike with a slacker seat angle will actually feel longer while seated than the bike with the steeper seat angle, even though
they have the same effective top tube on paper. So saying that you prefer a bike to have a particular ETT isn't really considering all the necessary information.
Longer Reach also means that the measurement from the BB to the front axle will be longer.
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Let's assume that you take a frame and increase the Reach by 25mm. The distance from the BB to the front axle will grow as a result and you now have a bike with a longer wheelbase. You can now shorten the bikes chainstay length to get the wheelbase back to where we started. Same overall footprint, just with more bike out in front and less in the back. Same stability at speed, but a lot easier to push the rear end around in corners and get the front wheel off the ground when you want to. Decreasing the chainstay without increasing the reach would shorten the wheelbase, potentially sacrificing stability at speed. And a slack seat angle combined with the shorter chainstay is going to shift rider weight even further over the rear axle.
With a longer reach dimension, riders can run a shorter stem while still having enough room in the cockpit, whether seated or standing. Short stems provide stability, which is a good thing when you're hanging on for dear life down a high-speed singletrack descent or pointing it through a technical section of trail. When climbing, your tire is less likely to get knocked off line by a root or ledge in the trail. We're going to make a blanket statement here that's intended to offend plenty of people...anyone who doesn't consider themselves a purely XC rider shouldn't be running a stem over 60mm on a mountain bike. That's being generous too. Really we think that max stem length
should be closer to 55mm, maybe even 50mm, but we'll leave some wiggle room in there.
We see people defying this rule regularly - probably because their bike's reach is too short so they put on a longer stem to provide enough room to move around. Or because their bike came spec'ed with a 90mm out of the box and they never changed it.
1UP Heavy Duty Rack Review
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Bike racks come in all shapes and sizes. Some are made for the roofs of vehicles while other go onto the back. The hitch mount variety tend to be the most secure, aerodynamic, and easily locked of the varieties currently available. Having your bike attached to the back of your vehicle for the first time while driving down the highway at 75MPH can be a bit stressful. You are expecting the rack to hold onto you bicylce that can cost over $10,000! This is where a heavily built rack with a strong latching system will give the buyer a true sense of ease. 1UP has been making racks for a number of years. 1UP takes their rack building to the extreme by using machining, billet and very high grade hardware to ensure a very robust design that will likely hold onto your bikes better than The Hulk!
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"We manufacture and sell quality bicycling products and back them up with the best customer service. Our 1 1/4" hitch mounted bike racks , 2" Hitch mounted bike racks, and roof tray bike racks are top quality. The aluminum bike racks are fast loading and light weight. Our modular rack design allows customers to have a 1 bike rack up to a 4 bike rack carrier. Our aluminum bicycle trainer is very sturdy and is the most quiet bike trainer on the market. It has a road-like feel, folds up small for storage, and has a 7lb flywheel. These cycling products are Made in the USA and come with a great warranty. With our 60-day money back guarantee, you have nothing to lose!"
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"The fastest Hitch-mounting and Bike loading Rack ever! 100% Made in the USA
Mounting the 1up USA Quik-Rack to your Vehicle in 10 seconds or less!
This rack has a solid 2" hitch bar and is a fixed 2-bike system. It cannot be reduced down to fit into a 1 1/4" hitch, and the second trays cannot be taken off to make a 1-bike system. It was designed for people who are interested or planning to carry up to 4 bikes. This rack is also great for off-road situations. It weighs 48lbs. It is $31 more expensive than a Quik-Rack + Add-on due to the heavier duty hitch bar.
The 1up USA Quik-Rack has more features than any other bike carrier. Fully assembled and ready for use. You won't get bags full of nuts and bolts to assemble. It mounts to your vehicle in 10 seconds with a unique corner expander ball that eliminates all wobble and play. To mount the Quik-Rack just insert it until it stops, then tighten the anti-theft security expander bolt (1-2 turns). That's it! No Hitch Pin or bolt to install or lose. 1up USA provides the anti-theft security tool needed for the 5 second job. To remove the Quik-Rack just loosen the anti-theft security expander bolt (1-2 turns) and remove the Quik-Rack from the hitch. The one-of-a-kind anti-theft security tool and expander bolt prevents rack or Add-On theft. We are so confident that our security system will prevent rack theft that if your Quik-Rack is stolen off your vehicle we will replace it for FREE! When not in use it folds down in just 5 seconds and fits back in it's reusable box.
Loading your bikes on the 1up USA Quik-Rack in 5 seconds or less.
Loading your bike could not be easier. Just open the arms, set your bike in then close the arms. Your bike is securely held by the tires only. It takes only 5 seconds to load your bike and 5 seconds to unload! There are no bungee cords, straps or clamps to fuss with. The 1up USA Quik-Rack can be used with most bikes and wheel sizes. All bikes with wheel sizes from 16 to 29 inch and as wide as 3-1/4 inch will fit the Quik-Rack. Bike wheel base up to 52 inch (axle to axle) will work also. When not in use it folds down in just 5 seconds and fits back in it's reusable box only 38" X 14" X 10 " and weighs only 48 pounds. Small enough to fit in the trunk of your vehicle. You will not find features like this on any other rack."
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Buying a bike rack is usually an ordeal based on whatever the local shop has in stock. This can be very limiting and will usually only give two options of racks to choose from. These racks typically go from $300-$400 in price. The 1UP is a $600 rack so it costs a fair bit more money than the major brands. But its build quality and retention system more than make up for the price hike. This rack is 100% made in the USA and if you can afford a $6000 bicycle paying a few hundred more for a more durable rack to hold it onto your vehicle shouldn't be a serious issue.
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The 1UP uses an arm on each end that goes up and over the wheels. It will fit 16"-29" wheels and using a 2.5 tire on it is a non issue. The silver part below the trays has ribs cut into it that the red arms slide along. The red arms have a rod that drops down into the ribs and provides the tension to hold the rack closed. To open the rack and get the bike off you press the arms in toward the bike and lift the small red arm up and make it level with the silver section. Then you can open the arm up and do the same to the other side then remove your bike.;)
Instead of using a receiver hitch pin to hold the rack onto the vehicle 1UP went another route. They used a ball on the back corner of the tongue. It floats on a large bolt with a special Allen Key head and as you tighten it down all the slack is removed between the tongue and the reciever by pushing the bolt into the receiver.
Overall the 1UP rack was a joy to use. It held the bikes in place going over rough terrain and moved very little. It has no play in the hitch like most mass produced racks have. This really cuts down on bike movement and over time will produce less wear and tear on the rack itslef.
Loading bikes into the 1UP was a snap it can be done in seconds. We ran DH, 29r's, "Enduro", and kids bikes in the rack wih no issue. Being able to fit a bike with a 52" Wheelbase is a sign that it should work for DH rigs for the next decade or so. The 1UP USA rack is in a league of its own. This is a highly refined rack made to hold bicycles securley to any vehicle with a hitch mount. In fact the quality of this rack is so high it would not be shocking to learn they make no money selling them for what they do.
The 1UP Rack is a beautiful system. The design, finish and fabrication of this rack is on another level. It's ease of use and and ability to hold up the bikes in a secure manner make it a no brainer. If you are looking for a nice hitch mount rack be sure to check out what 1UP has to offer. We would for sure suggest this rack to a friend or family memeber. Why hold your $8000 bike onto your $30,000 car with a $350 rack that wears out after a year or two and bounces all around inside the reciever when the roads get rough when you could just get the 1UP and be done with it.
Questions For 1UP USA
1. How did 1UP come to be?
Cal Phillips started 1UP USA in 2000 as he developed his first trainer and realized selling it through a distributor would make it too expensive. Ecommerce was just gaining traction, so he jumped on board and made his on website.
2. What were some of the products you stated building and designing first?
The trainer and quick-nuts were his first products.
3. What made 1UP decide to enter the bike rack market?
Cal saw the need for a platform style rack back in 2005 as he hated using other brands that just didn’t meet his expectations.
4. When designing the rack what were some of the main objectives you had in mind?
Fast loading, unloading and durability.
5. Where there any features you knew you just had to have on the rack?
By taking a look at ever other rack’s weaknesses then he just set out to solve as many problems as possible.
6. Why use a ball on the receiver to tighten it against the tongue versus say the traditional pin retention style?
That’s a huge feature for 1UP as it not only wedges it rock solid in the receiver, but also allows a couple inches of adjustment in or out depending the vehicle and clearance to the bumper.
7. The rack can hold up to 4 bikes with the extra trays bolted on correct?
All of our racks are rated for up to 2 add-ons. Our 2” 2-bike models are rated for up to 4 bikes.
8. Will the rack hold a Fat Bike? If no and plans on making a wider tray?
The fat-bike market is one of our largest niches. All of our racks are compatible with fat-bikes with the addition of our fat-bike spacer kit. We were the first to adapt!
9. Ever thought of doing a Motocross version of the rack?
Yes, it’s an idea on the drawing board.
10. If you have the 2” receiver is there an easy way to convert it to a 1 1/4”?
Our 1 ¼” racks are all sent with a 2” adapter.
11. Any tips or tricks you would like to share for using the 1UP or maintaining it over the years?
Keep them clean, check the fastening points where the rack pivots incase tightening or replacements are necessary. Don’t leave the rack on for years at a time. The receiver is the first thing to rust on all vehicles and will fuse to the hitch bar of the rack if not taken out on occasion.
12. Is the ribbed aluminum section that holds the red arms in place replaceable if it ever wears too much?
Yes, the glide bars can be replaced. It would take thousands of cycles to wear those out.
1UP USA, Bicycle Rack, Bike Rack, Hitch Mount |
Downill Mountain Bike Geometry Creates A Trickle Down Effect
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The last 15 years have provided some major breakthroughs in mountain biking. Wether it is brakes, rim material, suspension designs, suspension systems from dampers to chassis refinements almost all the major findings come from the Downhill segment. This is where athletes push themselves and the equipment to the outer limits reaching insane speeds over rough terrain and just pounding the piss out of the products. Everything trickles down from Downhill and spreads into the other segments of the sport including Enduro , AM and even XC. This includes bike geometry which has becomes longer and lower over time.
Take a look at the chart above these are all medium bikes. Over the years the TT and WB has become longer while the BB has become lower. The biggest difference is probably in the HT angles they have slackened a fair amount and Mondraker even had a production bike in the 62 neighborhood a few years back! These traits will help add stability, improve cornering and make steep sections more manageable.Many of todays trail bikes in the 6" segment have been following the same trend.
There are a few Enduro bikes out with 65 degree HA and boasting wheelbases in the 48" range. That is slack and long by any stretch. These 160mm bikes by virtue of geometry alone are a better handling bike than many dedicated DH bikes were from a decade ago. They have caught up to the older generation of downhill bikes in stability but the new dedicated gravity bikes are even longer and lower still with the added travel and braking power afforded by more travel.
Having trail bikes become lower, slacker and longer will allow riders to tackle terrain that used to be downhill specific. This can have both good or bad consequences in the long run. Will trails once ridden by a few small handfuls become the trails ridden by the majority some of which may not have the skills to be riding on in the first place? Maybe this will show new trails to riders that are responsible and will help to maintain the system and keep its location a closely guarded secret?
There are some trail bikes out now like the GT Sanction or the Guerrilla Gravity Megatrail that are much closer to a Downhill Bike in terms of geometry. These two bikes are at the far end of the trail bike spectrum. They are trail bikes for Downhillners not trail bikes for XC riders.
As downhill teams spend the money finalizing suspension designs, platforms,and bike geometry the rest of the Mountain Biking world waits in anticipation to see what the fastest on the planet have learned. These findings will typically be implemented into production Downhill bikes and eventually some of these changes will find their way onto the Enduro bikes or even the XC race bikes lines.
Mondraker Bikes is using a geometry they call Forward Geometry. Read a bit below about it...
"Mondraker is relaunching a new geometry concept that offers clear advantages in any category compared with a traditional geometry as all its benefits are focused on improving control, handling and confidence.
Forward Geometry is evolving, in combination with the new 27´5” wheel in All Mountain and Enduro, and 29er in Trail and Marathon, to provide a more democratic compromise and greater customisation options for all users. The basis of the FG concept remains unchanged; the geometry has longer top tubes that are completely balanced with shorter stems. The additional top tube length is the same as the stem loses, so as a result all contact points between the rider and the bike remain in the same position as in a traditional geometry; the only difference lies in the front wheel axle that is moved forward. There is no change in the rest of the geometry.
- Security in steep areas
The front axle is more advanced that in any other geometry making almost impossible to go over the bar in steep sections, it feels more secure and confident due to the slacker angle perception.
- Confidence at high speed
The longer wheelbase makes the bike much more stable over any terrain.
- Direct steering
The really short 10 mm, 30 mm or 50 mm stems mean much less handlebar movement to get the same front wheel angle, thus improving steering precision and making the bike extremely reactive.
- Uphill precision
The front wheel keeps the contact on the ground avoiding wheelies due the longer front-center length.
- Stability on rough sections
The FG defends a new weight balance between front and rear wheel making possible to load the front wheel a lot more than with a classic geometry. This possibility change your handling giving better grip in cornering and improving the control.
Forward Geometry offers new sensations in any category from Marathon to Downhill, as after a short period of adaptation to the handling of the bike overall control improves more than you had imagined. The new geometry makes your riding more stable, reactive and confident, giving you the chance to go faster"
Dave Weagle
The 2014 Méribel World Cup Predictatron
The UCI World Cup circus has wearily wound its way up the narrow road to Méribel Centre for the final round of the 2014 season. Both men's and women's titles are up for grabs, so before the bikes even roll out of the pits, let's have a guess at what may (or may not) happen...
It’s good to be back
The UCI World Cup is back in the Alps! Flat-out hillsides, massive turns, huge woods sections, expensive crepes... You name it, we're back! Short but fast Windham received mixed reviews in the pits, but there's a palpable sense of anticipation about Thursday morning's first practice session here in Méribel.
Decisions to be made
Only 82 points currently cover the UCI World Cup leader, Josh Bryceland and his Specialized Racing rivals, Troy Brosnan and Aaron Gwin. With 50 up for grabs in qualifying and 200 for the win, it's all to play for. But do they all simply go for the win and risk it all or play the maths game and race their title rivals?
Advantage Ragot
In the women's title race the points gap between Manon Carpenter, Emmeline Ragot and Rachel Atherton is 120. Ragot downplayed her title credentials earlier in the year, preferring to focus on her studies, but a win in Windham has her right back in the hunt. She's the only one of the three to have raced this track. Oh, and she's French. In France.
Flying Kiwis
With the title races so close, it's important to remember that their protagonists aren't the only potential winners of the round itself. Blenkinsop and Macdonald are our inside tips for the top. Sam hasn't won a World Cup since 2008, but one look at the final wide open section here can't help but conjure up images of Schladming 2008.
Likewise, Brook took his debut win just up the road in Val d'Isère and knows how to go fast in this part of the world. More importantly however, this is a track where hanging it out, fast and loose deep into a run looks essential. That's something they can both do in spades.
Pressure is on
The team sheets of the UCI World Cup are fairly cyclical things. You'll get a couple of seasons with things remaining pretty stagnant, then in one off season everything can change. We're on the cusp of just such an off season and, for those riders not selected for the World Championships in Norway, this is a last opportunity to shine and impress current or potential employers.
Don't forget that you can follow all the build up to the weekend's racing on our LIVE BLOG here.
Want to experience the best of RedBull.com on the move? Get the mobile app for iPhone and Android at RedBull.com/app.
2014 Devinci Spartan RR Enduro Machine
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Built for the spinning globe of terrain changes under your wheels, Devinci’s new Spartan comes battle equipped. From Devinci Alltricks.com Enduro racing storming the international Enduro race circuit to backyard bike park sessions, Spartan rolls in on full-suspension 27.5-inch Split-Pivot credentials— with ample 165mm rear and 160mm fork travel. While amped frame rigidity makes Spartan an upslope annihilator and bolsters downhill precision for pinning it across turbulent terra firma. Devinci Spartan. Hammer the throttle and launch the gap between freeride adventure and the exploding world of Enduro racing today.
Specifications
FORK Rockshox Pike RCT3 27.5 Dual air 160mm
REAR SHOCK Monarch Plus RC3
TIRES Schwalbe Hans Dampf Trailstar super gravity
FRONT WHEEL DT Swiss E 1700
REAR WHEEL DT Swiss E 1700
FRONT BRAKE SRAM XO trail
REAR BRAKE SRAM XO trail w/connectamajig
REAR DERAILLEUR SRAM XO1 actuation
REAR SHIFTER SRAM XO X -actuation
CRANKSET SRAM XO1 32T
HANDLEBAR Chromag BZA 780mm
STEM Chromag BZA 35
SADDLE Saddle SDG Fly RL, Black
SEATPOST Rockshox reverb stealth 125mm
WEIGHT 13.60 kg / 30.00 lbs
