[troy]

Little update.

CS extended to 16.7" (425 mm) for 27.5" wheels, WB to 46.85" (1190 mm)

BB height raised to 13.2" (335 mm) with 2.3 x 27.5 wheels

ST angle changed to 74 deg.

Seatpost dia. 31.6 mm

Have to add front derailleur mount to the front triangle and idler mount to the drive side aluminum plate, shock mount to the front triangle + change tubing thickness a little bit, tweak the swingarm a little. What do You think guys?

 

[MmmBones]

looks hella moar kewler

 

[jstuhlman]

looks good! i like a higher bb than most modern standards, so i'd try to raise it even further if i was building it for myself.

 

[troy]

looks good! i like a higher bb than most modern standards, so i'd try to raise it even further if i was building it for myself.

I want it to be 26 and 27.5 compatible so had to rise bb a little, otherwise it would be too low for 26" wheels. What bbh would be better in Your opinion?

 

[jstuhlman]

i'd probably like 13.5" at least, but i ride a bike from 2010 w/a bb height of 14.25" unsagged. i feel like i hear people compaining of pedal strikes a lot more than i used to. i guess it also depends on what kind of terrain you ride. i prefer it as rocky and rooty as possible.

 

[4130biker]

I like your design and thoughts going into it. The rear end looks better IMO. Keep it up!

 

[4130biker]

Will the derailleur tolerate that much movement (mounted to the Al plate) without hitting the chain when deep in the travel? The bikes I've seen it work on have much lower pivots, typically.

 

[troy]

Will the derailleur tolerate that much movement (mounted to the Al plate) without hitting the chain when deep in the travel? The bikes I've seen it work on have much lower pivots, typically.

What I ment was that the der. mount will be at the drive side steel plate @ front triangle and idler @ alu plate. My mistake.

 

[4130biker]

What I ment was that the der. mount will be at the drive side steel plate @ front triangle and idler @ alu plate. My mistake.

Ahhhh, I see. Cool! I dig the breezer style dropouts too. So clean.

 

[OBB]

I want it to be 26 and 27.5 compatible so had to rise bb a little, otherwise it would be too low for 26" wheels. What bbh would be better in Your opinion?

Leave the 26" wheels behind and look to now and the future. BTW, 335 BBH is pretty nice, that's 10mm below on a 27.5 2.3 HR2 equipped bike. Also consider your bike's rate for where it sits when sagged as that can affect the end geometry.

If you're set on using both wheels, you'll have to devise some methods to ensure the geo stays static as the wheels change. That makes things complicated as you'll need multiple systems to maintain BBH and drop, reach, HTA and STA. Best leave it with one wheel size, 27.5 being the more modern choice.

 

[troy]

Leave the 26" wheels behind and look to now and the future. BTW, 335 BBH is pretty nice, that's 10mm below on a 27.5 2.3 HR2 equipped bike. Also consider your bike's rate for where it sits when sagged as that can affect the end geometry.

If you're set on using both wheels, you'll have to devise some methods to ensure the geo stays static as the wheels change. That makes things complicated as you'll need multiple systems to maintain BBH and drop, reach, HTA and STA. Best leave it with one wheel size, 27.5 being the more modern choice.

I'm not talking about using 26 and 27.5 at the same time. Geometry would not change except BBH (the only thing You are changing in the system is tire diameter, WB stays the same, so do HA and other parameters). 26 vs 27.5 would be rider choice.

With 2,4" 650b Maxxis tires BBH is 340 mm (those tires, just like schawlbe are a little bigger than the others)

 

[Sandwich]

I think it looks great, nice job.

 

[TrumbullHucker]

looks awesome dude!!!!

 

[tomasis7]

looks awesome dude!!!!

+1

 

[kidwoo]

27.5 being the more modern choice.

Actually that's a good point.

Don't even make this frame unless you can do it out of carbon fiber. I mean it really is the modern choice.

Wear a fanny pack once you get it all together as well. It's truly the choice of modern endurpers.

 

[kidwoo]

And that triangulated swingarm looks WAY better

The whole thing is looking pretty damn good.

 

[OBB]

I'm not talking about using 26 and 27.5 at the same time. Geometry would not change except BBH (the only thing You are changing in the system is tire diameter, WB stays the same, so do HA and other parameters). 26 vs 27.5 would be rider choice.

With 2,4" 650b Maxxis tires BBH is 340 mm (those tires, just like schawlbe are a little bigger than the others)

27.5 forks have a longer A-C so the geo will change. If you design for 27.5, then the 26" version will get a lower BB, a steeper HTA and STA. Reverse effect if you design around 26 and install 27.5 wheels and fork. Your design chooses to compromise between both so that either works ok, but not great. Best focus on one wheel size. If you're particular about 26" wheels, then go with those. Nothing wrong with them.

FYI, the difference between 26 and 27.5, between forks and wheels, is usually 25mm in front end height. Varies between makes/models of forks, tires and rims.

 

[kidwoo]

^ For reference, I took two different 27.5 frames and put 26" forks and wheels on them. A new nomad and a Norco range.

Both BBs dropped about 0.7" and headangles steepened up by half a degree. That's with pikes. The A-C difference on those between wheelsizes is only 10mm...and since both wheels go up or down in size that's going to be your only difference relative to each other.

Other than BBs, the differences aren't huge switching wheels. The bigger difference is going to be how the wheels themselves handle IMO.

 

[HAB]

'woo, any reason you didn't use a 27.5 fork to keep the geometry changes a little smaller?

 

[OBB]

Other than BBs, the differences aren't huge switching wheels. The bigger difference is going to be how the wheels themselves handle IMO.

Got it. I was imagining a static BB height by having the rear axle in different positions depending on the wheel size.

Still not great to have a 10mm AC increase for the fork and 11-12 increased axle height from the wheels for the 27.5 models. The 10mm AC increase can be 3-4mm at the BB. If you make the BBH acceptable for the 27.5 model, then the 26" bike will be scraping the ground being 13-14mm lower. FYI, the nice riding 27.5 bikes out there have 330-335 BBHs, and something in the 315 range will be very low.

 

[kidwoo]

Ah......moving the rear axle for each......gotcha.

FYI, the nice riding 27.5 bikes out there have 330-335 BBHs,

I know, it's kind of pissing me off. Fewer frame options to put real wheels on. They're getting too damn low

The nomad I switched up was about 318mm. With the way that frame rides, I did think it was a little low. It handled like a champ but just gives up too much travel right around sag on itty bitty things (like what you were saying earlier about leverage at sag) and I would hit things climbing.... It was awesome descending though. The range I've got is about 322 with 26" stuff without as much of that wallow. It works really well.

HAB: That's what I'm saying, the geo changes aren't that significant. The only real big one is BB height, which I very much wanted to drop. I didn't see a need to buy a new fork for half a degree or less of head angle change. You can do that with tires. Plus it would add a little unnecessary twitch to the steering with the bigger offset.

 

[HAB]

Okay if you were using a fork you already had, that 100% makes sense. The difference is minor.

 

[troy]

@OBB I do understand what You are trying to say, but You have to understand 1 thing: You can't predict what the rider will do with his bike. 1 guy will put 2,5" tire to the front, 2,3" to the back, other guy will put 150mm fork in there, other one 160mm, one will go with fox other with marzo with different A2C, different headsets, one will set up SAG to 25% and the other one to 30%, and so on, it is just too many options to consider.

There is no compromise, frame is designed around 552 A2C Pike fork and 27.5" wheels. If You don't like it or have no money to buy new fork and wheels - CS is short enough so You can install 26" wheels and have fun too, 0.5deg ha and sta change won't kill You. I might consider slackening hta to 65.5 deg for that reason, that is all.

With 542 A2c and 2.5"x26" wheels BBH is 324mm (12.75") and HA changes from 66 to 66.4 deg.

 

[kidwoo]

Now let's talk about that leverage curve

 

[troy]

Now let's talk about that leverage curve

It looks like a banana!

 

[kidwoo]

Like a banana doing a sit up or a banana doing a downward dog?

 

[troy]

Like a short legged banana doing a sit up.

Seriously tho, It is very progressive up to the SAG point, then it flattens a little bit and goes linear.

 

[kidwoo]

Facing east or west?






Just put up the picture dammit!

 

[troy]

Production model will probably be sligtly less progressive till the SAG point and more digressive at the end of travel. This is leverage for the proto to verify all assumptions and cope it with HV air can.

 

[kidwoo]

Hooray!

Looks better than a lot of production bikes.


That's an east facing banana with a mild woodie just FYI. Technical term.

 

[HAB]

Looks better than a lot of production bikes.

Making it overall a little less progressive as you described would probably be more gooder, but that already looks decent.

 

[OBB]

Production model will probably be sligtly less progressive till the SAG point and more digressive at the end of travel. This is leverage for the proto to verify all assumptions and cope it with HV air can.

Looks good. Rate is a bit high off the top. Might be hard to stay at sag with reasonable pressures. With a Fox LV unit, I'm guessing body weight + 25% which is alot. Is this frame specifically designed around high volume air cans? If so, the starting PSI will drop, maybe to body weight +15% which is a bit better.

The larger air can will also flatten the progressive end stroke. Looks well suited to a CCDBA or a Vivid Air, but not so much with smaller air cans. Too progressive

Also, consider that a debonair can will compound the supple (high) rate off the top making the bike sit into its travel a bit more.

What size shock? 7.875 x 2.25 I assume?

 

[Jm_]

Why constrain it with a front derailleur?

 

[jstuhlman]

thought the same thing-maybe for upper chain guide mounting?

 

[troy]

@OBB yes it is designed around HV air can shock. In the proto frame, there will be 2-3 shock mount options (on the main triangle) to fine tune the leverage for different shocks. Maybe I will leave them for production model, we will see.

8.5"x2.5" shock.

@Jm_ because people wanted a FD mount... 95% in here are using 2x setup. If i would make one for myself it would be 1x only, trust me.

@jstuhlman there will be ISCG 05 in there, just like in the 1st version, forgot to model it in this iteration.

 

[no skid marks]

IMO you should design it 100% for 27" wheels. If someone want 26" wheel model, just make new swing arm plates.
Forget the front mech too. 1 x all the way.Unless you're throwing a gearbox in there. You don't want to sell your bikes to the type of people that use front mechs

 

[jonKranked]

No front mech. Maybe iscg tabs for us Luddites that run chain guides.

How much?

 

[kidwoo]

That leverage ratio change is still less than this thing everyone's got a boner over.

 

[HAB]

That leverage ratio change is still less than this thing everyone's got a boner over.

Not the thing I have a boner over.

 

[Jm_]

@Jm_ because people wanted a FD mount... 95% in here are using 2x setup. If i would make one for myself it would be 1x only, trust me.

The thing about 1x drivetrains is that you don't have to try and balance out granny gear with middle ring anymore. Most suspension bikes are compromises trying to make either one "not suck". Going 1x frees you up considerably. The drivetrains are here and 1x10 or 1x11 are proven, with gearing as low as we had just a few years ago on 3x9 setups, or even lower.

I'll concede that lots of people can't reckon not having a FD though, even if the gear combos are completely redundant and they never go high enough to use the "extra" gears, they'll still think they need it.