Enduro/gravity bike suspension and geo

[Thermophage]

Answer to the seat tube difference - you're measuring actual, whereas they list effective, by drawing a line between the BB and the seat post when the saddle is level with the bars. Seat tube kinks, so eff will always be different to actual.

 

Head angle - Evil specs their bikes with a fork of a certain Axle to Crown height. if you have a fork with a lower A2C, you will have a steeper HA. If you have a fork with a longer A2C, you will have a slacker HA. Not all 160mm forks have the same A2C measurement. 

Also...if your bike is not on a perfectly level surface and you measure the angles without zero'ing your measuring device to the surface the bike is on....you're not measuring the true HA, SA, etc

Good thing to do is take a side-on picture, then make a line drawing in Paint or photoshop or PowerPoint and then measure the angles.

[Thermophage]

I would assume Trailtech would sell the correct A2C.

But it is everything I thought, except for the effective STA, don't see why they would list this as opposed to the actual STA.

Assumption is the mother of all...

But TBH, a 10mm change in A2C will only result in roughly 0.5 degree change in HA...So your 2.5 degree change is what, a 50mm A2C difference between spec and actual if your angle measurements are correct. That can also come from running a longer fork than spec too if that's the case. But it's more likely your measurements are off

[Captain Fastbastard Mayhem]

I would assume Trailtech would sell the correct A2C.

But it is everything I thought, except for the effective STA, don't see why they would list this as opposed to the actual STA.

There's no such thing as a "correct" a2c. Different forks from different manufacturers have different measurements. They're just higher or lower. 

 

Also - effective seat tube angle is used as it's the most accurate way to measure it, across different frame designs. Some frames have no kinks in the ST, some do, some have bigger kinks and Knolly's seat tube is in a totally different area entirely, forward of the BB. It gives an element of parity across different manufacturers, so that Cotic (for example) who have a straight seat tube from the BB all the way to the seat collar, don't seem to have a vastly superior ST angle to that of, say, Evil. They measure to the same space, from the same space, being the height of the saddle when level with the bars, from the BB. BUT - they *should* list actual ST angle as well, as that'll allow you to see if your ass will be moving faster rearwards for every mm the saddle is raised when higher than the bars. 

Edited February 13, 2019 by Captain Fatbastard Mayhem

[Captain Fastbastard Mayhem]

Assumption is the mother of all...

But TBH, a 10mm change in A2C will only result in roughly 0.5 degree change in HA...So your 2.5 degree change is what, a 50mm A2C difference between spec and actual if your angle measurements are correct. That can also come from running a longer fork than spec too if that's the case. But it's more likely your measurements are off

Yep. This. 

[PhilipV]

, being the height of the saddle when level with the bars, from the BB.

Are you making this up?

Who climbs with their seat that low?

[Grease_Monkey]

Are you making this up?

Who climbs with their seat that low?

That's really how they measure effective SA - just stupid. That's why the only number that matter is actual SA - especially for guys on the taller end of a size that run their seatposts far out. Then actual becomes very slack.

[Captain Fastbastard Mayhem]

Are you making this up?

Who climbs with their seat that low?

sadly, no...

[Headshot]

That's really how they measure effective SA - just stupid. That's why the only number that matter is actual SA - especially for guys on the taller end of a size that run their seatposts far out. Then actual becomes very slack.

As long as the user knows this, its not much of a problem. I didnt but its never really bothered me. A bike that has a steeper STA is just that, steeper and because its a standard measure you can compare bikes easily. 

[Grease_Monkey]

Okay, so question for the geometry knowers.

 

I'm getting a Transition Sentinel on Monday, much slacker and longer than anything I have owned before. Transition bases their geo on what they call SBG (Speed Balanced Geo). Basically super long (475mm reach in L), super slack (64° HA), which is balanced with a short stem (40mm), steep SA, and a reduced offset fork (42-44mm as oposed to 51mm) to being the front wheel closer to the rider which reduces front wheel flop in slow speed stuff and gives better traction. By all accounts the 7mm reduced offset actually makes a difference and is not just some gimic.

 

 

I am building everything over from my Evil incl. my standard offset Ribbin. Somewhere down the line I want to buy a Fox 36, Grip 2 fork with reduced offset, but they are expensive, so it will take a while to save up. For now the Ribbon with standard offset will do the job.

 

So my question, SBG is based on a 40mm stem and short offset fork to get weight over the front wheel. My logic tells me that when using a standard offset fork, using a 50mm stem may have the same effect getting weight over the front wheel. What do you guys think? Will it work, or should I just stick with a 40mm stem?

 

Obviously I will play around with both to see what works for me, but everything on the bike will be new and take a while to get used to - so some advice on a starting point would be good if anyone has experience with this?

[Thermophage]

Okay, so question for the geometry knowers.

 

I'm getting a Transition Sentinel on Monday, much slacker and longer than anything I have owned before. Transition bases their geo on what they call SBG (Speed Balanced Geo). Basically super long (475mm reach in L), super slack (64° HA), which is balanced with a short stem (40mm), steep SA, and a reduced offset fork (42-44mm as oposed to 51mm) to being the front wheel closer to the rider which reduces front wheel flop in slow speed stuff and gives better traction. By all accounts the 7mm reduced offset actually makes a difference and is not just some gimic.

 

 

I am building everything over from my Evil incl. my standard offset Ribbin. Somewhere down the line I want to buy a Fox 36, Grip 2 fork with reduced offset, but they are expensive, so it will take a while to save up. For now the Ribbon with standard offset will do the job.

 

So my question, SBG is based on a 40mm stem and short offset fork to get weight over the front wheel. My logic tells me that when using a standard offset fork, using a 50mm stem may have the same effect getting weight over the front wheel. What do you guys think? Will it work, or should I just stick with a 40mm stem?

 

Obviously I will play around with both to see what works for me, but everything on the bike will be new and take a while to get used to - so some advice on a starting point would be good if anyone has experience with this?

Simple answer is save your money, keep your parts, run a 50mm stem.

I had the exact reservations when I moved late last year from a 2016 Banshee Spitfire, which has pretty modern geo, to a 2018 Transition Patrol.

Running a 44mm offset as opposed to the 37mm offset. Initially running a 33mm stem which was perfect on the Spitfire but "odd" on the Patrol. Swapped over to a 50mm stem and felt great. Although this MIGHT be because I had adjusted a bit to how differently one rides the SBG bikes.

So don't consider changing forks just yet. We have a mate with a XL Sentinel and reduced offset fork (Ribbon Coil as those are available in a reduced offset too). SO potentially you guys could wif...bike swap and see how much difference there is ITO handling etc.

I can tell you one thing, the 64HA is no detriment whatsoever to climbing performance while seated on these bikes. The steeper ST really puts you in a forward position and front wheel grip is amazing. Similarly if you REALLY want to get the most out of it when going down or going fast you will need to learn to ride the front of the bike more than you may be used to with the Evil.

[Captain Fastbastard Mayhem]

Okay, so question for the geometry knowers.

 

I'm getting a Transition Sentinel on Monday, much slacker and longer than anything I have owned before. Transition bases their geo on what they call SBG (Speed Balanced Geo). Basically super long (475mm reach in L), super slack (64° HA), which is balanced with a short stem (40mm), steep SA, and a reduced offset fork (42-44mm as oposed to 51mm) to being the front wheel closer to the rider which reduces front wheel flop in slow speed stuff and gives better traction. By all accounts the 7mm reduced offset actually makes a difference and is not just some gimic.

 

 

I am building everything over from my Evil incl. my standard offset Ribbin. Somewhere down the line I want to buy a Fox 36, Grip 2 fork with reduced offset, but they are expensive, so it will take a while to save up. For now the Ribbon with standard offset will do the job.

 

So my question, SBG is based on a 40mm stem and short offset fork to get weight over the front wheel. My logic tells me that when using a standard offset fork, using a 50mm stem may have the same effect getting weight over the front wheel. What do you guys think? Will it work, or should I just stick with a 40mm stem?

 

Obviously I will play around with both to see what works for me, but everything on the bike will be new and take a while to get used to - so some advice on a starting point would be good if anyone has experience with this?

As thermophage says above, but also... Ribbon Coil. Cheaper, coil, ramp control goodness. Or, Lyrik RC2. LOVING mine.  

Edited February 14, 2019 by Captain Fatbastard Mayhem

[Thermophage]

Also, Cane Creek is releasing the Helm in reduced offset shortly and having had one for the last few months I finally hit the sweet tinkering spot on the fork and holy hell is it nice 

[Jewbacca]

they have some sexy hardtails!

They are basically just 3 tattoo'd weirdo's who make some pretty weird and wonderful bikes!

 

I am on the look out for a proper fun to ride Trail bike. 

 

Everything these days is too slack and a tank.

 

The Marin Rift Zone looks nice, but our trails aren't steep enough for any of this crazy long and slack stuff.

 

If we had parks with uplift I would have bought one of those FR frames from Sick months ago!

 

As it stands an affordable trail bike with decent reach and pedalable numbers seems to be missing.

 

The Marin rift zone comes in at 14kg less pedals.

 

If any of you have any decent suggestions for a really fun, pedallable trail bike that isn't a western Australian road train I'm all ears!

[Grease_Monkey]

Simple answer is save your money, keep your parts, run a 50mm stem.

I had the exact reservations when I moved late last year from a 2016 Banshee Spitfire, which has pretty modern geo, to a 2018 Transition Patrol.

Running a 44mm offset as opposed to the 37mm offset. Initially running a 33mm stem which was perfect on the Spitfire but "odd" on the Patrol. Swapped over to a 50mm stem and felt great. Although this MIGHT be because I had adjusted a bit to how differently one rides the SBG bikes.

So don't consider changing forks just yet. We have a mate with a XL Sentinel and reduced offset fork (Ribbon Coil as those are available in a reduced offset too). SO potentially you guys could wif...bike swap and see how much difference there is ITO handling etc.

I can tell you one thing, the 64HA is no detriment whatsoever to climbing performance while seated on these bikes. The steeper ST really puts you in a forward position and front wheel grip is amazing. Similarly if you REALLY want to get the most out of it when going down or going fast you will need to learn to ride the front of the bike more than you may be used to with the Evil.

Good to hear, so the logic checks out then, I will stick to the 50mm stemm and my current Fork (which I love).

[Hairy]

First things first .... congrats on the bike.

 

Now to make your life simple, can you not just get the Ribbons lowers in a 42-44mm offset?

 

If so, I am sure it could save you a wad of cash that can be spent on a good couple of beers?

 

Okay, so question for the geometry knowers.

I'm getting a Transition Sentinel on Monday, much slacker and longer than anything I have owned before. Transition bases their geo on what they call SBG (Speed Balanced Geo). Basically super long (475mm reach in L), super slack (64° HA), which is balanced with a short stem (40mm), steep SA, and a reduced offset fork (42-44mm as oposed to 51mm) to being the front wheel closer to the rider which reduces front wheel flop in slow speed stuff and gives better traction. By all accounts the 7mm reduced offset actually makes a difference and is not just some gimic.


I am building everything over from my Evil incl. my standard offset Ribbin. Somewhere down the line I want to buy a Fox 36, Grip 2 fork with reduced offset, but they are expensive, so it will take a while to save up. For now the Ribbon with standard offset will do the job.

So my question, SBG is based on a 40mm stem and short offset fork to get weight over the front wheel. My logic tells me that when using a standard offset fork, using a 50mm stem may have the same effect getting weight over the front wheel. What do you guys think? Will it work, or should I just stick with a 40mm stem?

Obviously I will play around with both to see what works for me, but everything on the bike will be new and take a while to get used to - so some advice on a starting point would be good if anyone has experience with this?

[Grease_Monkey]

As thermophage says above, but also... Ribbon Coil. Cheaper, coil, ramp control goodness. Or, Lyrik RC2. LOVING mine.

I may in the future do a coil conversion on my Ribbon, but would want to ride one extensively before doing it - coz once it's done there is no going back!

 

And before I would conver to coil in the front I would do coil on the back. But once again, am very happy with air, so I would wanna test a coil out lots before even thinking of it.