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Posted: Jun 24, 2019 at 11:08 Quote
R-M-R wrote:
ktm87 wrote:
how does it ride so far? ive been working on this for awhile which is extremely similar. ordering material this week for it
]

If you like, I could give some kinematics and geometry feedback if you send the Linkage file.

yea i can send it to you. geometry is what i want so im set with that but just curious on linkage layout. i have a pretty progressive curve which is what i was aiming for too. bike will have a pinion and a idler up top to deal with chain growth

Posted: Jun 24, 2019 at 11:55 Quote
ktm87 wrote:
how does it ride so far? ive been working on this for awhile which is extremely similar. ordering material this week for it

Hi, I am really impressed of the kinematics. It genereates so much traction, no matter what you are doing on the bike. especially the climbing is insane!
But what you definetly have to keep in mind is that the chainstays really extend a lot, when you are going throgh travel. I´ve put the main Pivot 240mm above the BB, and i would not go any higher than that.
Also, your concept has got a small but very important difference to mine: While yours is a single pivot, I´ve built a inverted horst link, which gives you a lot more controll over the braking behaviour (Anti Rise).
The most important things before thinking about progression are allways anti-rise and anti squat, because these are much harder to control, than the progression and shock stroke etc..
You will also have to keep in mind, that the anti-squat ratio, linkage calculates, only will be correct for a 1:1 gear
at the pinion, because the chain-foce changes.

I hope that my english is not too bad and i hope i could help you. Smile

Posted: Jun 24, 2019 at 12:02 Quote
JokerT wrote:

Hi, I am really impressed of the kinematics. It genereates so much traction, no matter what you are doing on the bike. especially the climbing is insane!
But what you definetly have to keep in mind is that the chainstays really extend a lot, when you are going throgh travel. I´ve put the main Pivot 240mm above the BB, and i would not go any higher than that.
Also, your concept has got a small but very important difference to mine: While yours is a single pivot, I´ve built a inverted horst link, which gives you a lot more controll over the braking behaviour (Anti Rise).
The most important things before thinking about progression are allways anti-rise and anti squat, because these are much harder to control, than the progression and shock stroke etc..
You will also have to keep in mind, that the anti-squat ratio, linkage calculates, only will be correct for a 1:1 gear
at the pinion, because the chain-foce changes.

I hope that my english is not too bad and i hope i could help you. Smile

ahh yes i didnt look close enough at yours. interesting set up. i love how it all came out.

Posted: Jun 24, 2019 at 20:42 Quote
ktm87 wrote:
how does it ride so far? ive been working on this for awhile which is extremely similar. ordering material this week for it

If you make two I'll buy the other

Posted: Jun 25, 2019 at 5:01 Quote
thunder-nuggets wrote:
ktm87 wrote:
how does it ride so far? ive been working on this for awhile which is extremely similar. ordering material this week for it

If you make two I'll buy the other

after i get some time on it i plan on making them to order if other people want them. probably next year

Posted: Jun 26, 2019 at 0:27 Quote
JokerT wrote:
ktm87 wrote:
how does it ride so far? ive been working on this for awhile which is extremely similar. ordering material this week for it

Hi, I am really impressed of the kinematics. It genereates so much traction, no matter what you are doing on the bike. especially the climbing is insane!
But what you definetly have to keep in mind is that the chainstays really extend a lot, when you are going throgh travel. I´ve put the main Pivot 240mm above the BB, and i would not go any higher than that.
Also, your concept has got a small but very important difference to mine: While yours is a single pivot, I´ve built a inverted horst link, which gives you a lot more controll over the braking behaviour (Anti Rise).
The most important things before thinking about progression are allways anti-rise and anti squat, because these are much harder to control, than the progression and shock stroke etc..
You will also have to keep in mind, that the anti-squat ratio, linkage calculates, only will be correct for a 1:1 gear
at the pinion, because the chain-foce changes.


I hope that my english is not too bad and i hope i could help you. Smile

@Ktm87, did you design it as a single pivot or a multi link of some type?

Posted: Jun 26, 2019 at 5:10 Quote
adespotoskyli wrote:

@Ktm87, did you design it as a single pivot or a multi link of some type?

orginally it was a swingarm 4 bar but ive moved to a horst link since that picture so i could get the pivots where i wanted for little better numbers

Posted: Jul 10, 2019 at 13:51 Quote
First post for me but been reading and watching a lot and I have to say hats off to you guys for all those awesome builds!

Now it's time for me to build one and before I'm getting to much into the design I thought I might get some opinions from you guys on what I've done so far. The plan was a progressive 29er trailbike with similar travel numbers to my exisiting Pivot Mach 5.5 to have something to compare it to. As a reference, I'm 176cm (5'9'') tall.
Rough frame shape in Linkage to get a feel, final clearance check and design will probably be done in Blender as I know my way around it quite well.
Intending on running it with a coil shock, but might go with a MRP progressive spring, some insights on the progression of lev.-ratios for coil shocks would be welcome.
Antisquat above 100% for a good portion of the travel in lower gears...
...and all below 100% in the higher gears for going downhill, I'm not much of a sprinter.
For building it, I plan to make it from chro-mo tubing and fillet braze it with brass. The bikeshop I work at is going to expand and get a framebuilding shop this autumn which I'll be able to use.

Posted: Jul 10, 2019 at 14:20 Quote
NickBosshard wrote:
First post for me but been reading and watching a lot and I have to say hats off to you guys for all those awesome builds!

Now it's time for me to build one and before I'm getting to much into the design I thought I might get some opinions from you guys on what I've done so far. The plan was a progressive 29er trailbike with similar travel numbers to my exisiting Pivot Mach 5.5 to have something to compare it to. As a reference, I'm 176cm (5'9'') tall.

Rough frame shape in Linkage to get a feel, final clearance check and design will probably be done in Blender as I know my way around it quite well.

Intending on running it with a coil shock, but might go with a MRP progressive spring, some insights on the progression of lev.-ratios for coil shocks would be welcome.

Antisquat above 100% for a good portion of the travel in lower gears...

...and all below 100% in the higher gears for going downhill, I'm not much of a sprinter.

For building it, I plan to make it from chro-mo tubing and fillet braze it with brass. The bikeshop I work at is going to expand and get a framebuilding shop this autumn which I'll be able to use.

Geometry
Looks like you based it on a Large Mach 5.5. Keep in mind stack affects reach, so it will be between a Large and XL Mach 5.5. Not unreasonable for someone your height, especially with the steep seat tube angle. The combination of long reach and slack head angle will make it feel a lot longer on tight trails. If you want to make it more agile, go steeper on the head angle, don't reduce reach.

Anti-squat
- Your centre of mass looks a bit low, so anti-squat will be a touch higher than your current numbers, but still below current averages. I favour very high anti-squat.
- Is your model in "horizontal mode"?
- You must be using an idler if your pedal kickback is so low. If you're using an idler, why not use more anti-squat, since pedal kickback will be nearly zero?

Brake squat
It's high. Consider adding mounts for a floating brake to allow you to incorporate this later, if you choose.

Leverage
- Average: Looks good.
- Curve: For a coil, more progressivity is better, but there's only so much you can do without a shock link. I recommend a shock with position-sensitive damper, such as an EXT Arma / Storia v3 or Fast Fenix.

Overall packaging
I like it. Rear triangle is compact, seat tube isn't compromised, shock is accessible, room for a water bottle - nicely done.

Posted: Jul 10, 2019 at 16:23 Quote
Geometry wise I deliberately went a bit extreme especially compared to my medium Mach 5.5 (445mm reach) as I can always make another front triangle if it doesn't quite work, probably gonna make a rough prototype just to ride and test before the final version.

R-M-R wrote:
Your centre of mass looks a bit low, so anti-squat will be a touch higher than your current numbers, but still below current averages. I favour very high anti-squat.

Thanks for pointing out the COG. height! Anti-squat is deliberately somewhat low as this bike probably won't see a lot of climbing.

R-M-R wrote:
Is your model in "horizontal mode"?

Please explain, I'm still kinda new to suspension design and working with Linkage.

R-M-R wrote:
You must be using an idler if your pedal kickback is so low. If you're using an idler, why not use more anti-squat, since pedal kickback will be nearly zero?


No, not using an idler, trying to keep it simple. Now with the updated linkage(to get proper anti-squat with the new COG.) it's a bit higher but still low. Also a reason why I prefer the lower anti-squat

R-M-R wrote:
Brake squat
It's high. Consider adding mounts for a floating brake to allow you to incorporate this later, if you choose.

Kinda fixed that by playing around with the rest Big Grin

R-M-R wrote:
Curve: For a coil, more progressivity is better, but there's only so much you can do without a shock link.


Setteled on an even flatter curve and will probably go with an air shock but might try my progressive coil from my Mach 5.5.

Thanks for the quick, in-depth feedback!

Posted: Jul 10, 2019 at 17:55 Quote
NickBosshard wrote:
Geometry wise I deliberately went a bit extreme especially compared to my medium Mach 5.5 (445mm reach) as I can always make another front triangle if it doesn't quite work, probably gonna make a rough prototype just to ride and test before the final version.

I wouldn't call it extreme; just wanted to put it into context.

NickBosshard wrote:
Thanks for pointing out the COG. height! Anti-squat is deliberately somewhat low as this bike probably won't see a lot of climbing.

That's reasonable. More anti-squat will also produce a more rearward axle path, so it can have a dual benefit. Fears of pedal kickback interfering with suspension function are greatly exaggerated and can largely be addressed with a low-engagement hub.

NickBosshard wrote:
Please explain, I'm still kinda new to suspension design and working with Linkage.

There's a checkbox in the upper right for "horizontal mode". With it unchecked, the rear suspension curves are calculated with the suspension in pitch (rear compression only); with it checked, the curves are calculated with the bike in heave (both ends simultaneously).

NickBosshard wrote:
No, not using an idler, trying to keep it simple. Now with the updated linkage(to get proper anti-squat with the new COG.) it's a bit higher but still low. Also a reason why I prefer the lower anti-squat

Ah, I see now. I mistook the 32/10 kickback curve for 32/50. It's far too low for 32/50, hence my assumption you were using an idler, even though the bike image didn't show it. Now that I realize the curve was for 32/10, it makes sense.

NickBosshard wrote:
[Re: brake squat] Kinda fixed that by playing around with the rest Big Grin

How so?

NickBosshard wrote:
Setteled on an even flatter curve and will probably go with an air shock but might try my progressive coil from my Mach 5.5.

A progressive coil will help a little. Might as well try it, since you already have one.

NickBosshard wrote:
Thanks for the quick, in-depth feedback!

Salute

Posted: Jul 12, 2019 at 5:51 Quote
Amazing work as always.

Just wondered if anyone has been building with the new Trunnions shocks in mind? And if so, has anyone got measurements for the mounting widths and bearing choice ? Tried to find them through shock manufacturers but so far no luck.

Posted: Jul 12, 2019 at 7:07 Quote
NickBosshard wrote:
Thanks for the quick, in-depth feedback!
RMR is the real MVP. By far the most educational and awesome active user of PB.

Posted: Jul 12, 2019 at 7:20 Quote
scotteh wrote:
RMR is the real MVP. By far the most educational and awesome active user of PB.


^^^^ this RMR has helped me a ton. knows his stuff

Posted: Jul 12, 2019 at 8:05 Quote
Couldn't agree more serious depth of knowledge and awesome enough to give time towards others tup


 
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