Re: Derbis are pretty sweet.

Totally normal JBOT /

Ok, rode it today now that I got everything working.

It's fine, but I just can't leave it. I think it really needs to be the bike it was destined to be. I just can't climb these mountains at a moderate pace.

Gonna try porting stock and maybe convert the top end to cyl Reed since the fins cool so well. I can do pretty brutal porting and not need to go wc, that would be cool

Re: Derbis are pretty sweet.

Double Trouble Dan /

Derbi's are keepers.

Here is my setup in pictures if you want a mild 50+ MPH build.

IMG_7083.JPG
IMG_7079.JPG
IMG_7078.JPG

Re: Derbis are pretty sweet.

Estoril on a derbi is like chopping its ballz off. Need those rippems that estorils just can't put out to hit over 50 and still have the power to shred hills. Also I would recommend going back down to at least a 19 jbot, imo you usually lose top speed if you gear out variated bikes.

Re: Derbis are pretty sweet.

Totally normal JBOT /

I don't think I need any help with my variated builds. But thx.

I don't agree at all btw if that wasn't evident. I gear up all my variated bikes and they ripppppppp

Matter of fact I gotta add gears to my 50cc stock hobbit build.

It's fast now but it'll be insane with gears . The only way you'd be slower with taller gearing is if your motor is anemic. (edited)

Re: Derbis are pretty sweet.

just a suggestion, do your thing man!

Re: Derbis are pretty sweet.

Charles Cole (OFMC) /

First Polini Cup was won with one of those !

Re: Derbis are pretty sweet.

🇮🇹💦 Of the Loin /

I had a pyramid reed one that was fun

6 roller Laguna variator

21mm phbg

Custom MotoMatic sidebleed Destroyer

That actually got me to a solid 45 and I never ported the damn thing, totally stock

Re: Derbis are pretty sweet.

Totally normal JBOT /

> Daniel '' Wrote:

> -------------------------------------------------------

> just a suggestion, do your thing man!

Variation rant:

The thing is this.

Variation and trans tuning/gearing is one of my favorite arts.

That's been my secret to my bikes.

There's so much hp left over and wasted from a non modified or partially modded transmission. By changing the rate of the rear pulley's tension, and really maximizing its travel, and maximizing and modifying the front variator and fixed cheek for how deep the belt can drop in at rest, you can gear insanely tall and still get off the line like a rocket.

On my lil 50cc hobbit, i actually modded the rear pulley to the point where it's geared way too low.

Belt can stick out of the rear by like 4-6mm. It's crazy.

So when you take off, it actually takes a second or two for the belt to travel the distance it needs to where you can feel any acceleration. Didnt leave it there of course, but it's an interesting observation . Maximizing the variables!

By throwing gears in a bike that can adjust its variation so low, low end would not be lost at all, and as long as the power is there and the trans is tuned appropriately, you'll rip right to the top. It's just like some of those dudes that preach crazy high gearing but are slugs off the line. (Pete N? Idk) If you can get off the line fast with crazy gearing, the bike will get to top speed for sure as long as the trans is tuned right.

And all of this talk so far doesn't even bring stroke into this. PP Derbi is basically a hobbit with a 4mm stroker. So much torque to use in that cranks massive stroke to push thru whatever gearing you want.

I don't run bikes that rely on extreme rpms to get to top speed with low gearing..

Not my thing. Don't like ripping around on a dual variated bike that stays at 12-13k all the time. It's super annoying. 11k is about max I'll go.

Will say that I'm not a racer, won't ever be....but I do like to put the hammer down on rides, but I've got my style and really like it.

TLDR, tall gearing on variated bikes is GRRRRRRRREAT!

Re: Derbis are pretty sweet.

good rant. on the front you can only get so small, why not do low gears and make a wider belt ratio that goes higher

oh wait, duh, taller gears=wider ratio, derp.

Re: Derbis are pretty sweet.

Hey I know that derbi.

Re: Derbis are pretty sweet.

jbot, what motor? interested to see what u do. pull starter opens pandoras box on the derbis.

i got a flatreed slex, but i'm still kind of a derbi noob.

Re: Derbis are pretty sweet.

Totally normal JBOT /

I don't like wide belts unless the engine is making crazy power. Nothing will fuck up variation more than a wide belt. More importantly a thick belt. If a belt was wide and thin, that's cool, but most wide belts are super thick (BX), so they don't bend easily over our lil pulleys.

I'm actually going to explore some vari angle experiments soon on my motobecane to allow a thin belt to get more variation with a limited variation travel (steeper cheeks, baby)

Re: Derbis are pretty sweet.

> JBOT Admin Wrote:

> -------------------------------------------------------

> I don't like wide belts unless the engine is making crazy power. Nothing

> will fuck up variation more than a wide belt. More importantly a thick

> belt. If a belt was wide and thin, that's cool, but most wide belts are

> super thick (BX), so they don't bend easily over our lil pulleys.

>

> I'm actually going to explore some vari angle experiments soon on my

> motobecane to allow a thin belt to get more variation with a limited

> variation travel (steeper cheeks, baby)

Noob question : How small are these pulleys at the narrowest point ? Near shaft size or ???

Just trying to get a better understanding of what you're doing .

Re: Derbis are pretty sweet.

PD- The belt rides the cheek faces so even wide open it will be noticeably larger than the shaft diameter. Angle of the cheek wall, strength of the contra spring, and belt specs are all opportunities to tune.

Re: Derbis are pretty sweet.

> Jonathan R Wrote:

> -------------------------------------------------------

> PD- The belt rides the cheek faces so even wide open it will be

> noticeably larger than the shaft diameter. Angle of the cheek wall,

> strength of the contra spring, and belt specs are all opportunities to

> tune.

The same as any other belt /pulley set up . It's the 'noticeably larger than the shaft' part I was trying to get a handle on .

Re: Derbis are pretty sweet.

Chloe Feldman /

Jbot in derbi world?...uh oh. It was bound to happen eventually. Time to break out the popcorn n a lawn chair. (edited)

Re: Derbis are pretty sweet.

> Jonathan R Wrote:

> -------------------------------------------------------

> PD- The belt rides the cheek faces so even wide open it will be

> noticeably larger than the shaft diameter. Angle of the cheek wall,

> strength of the contra spring, and belt specs are all opportunities to

> tune.

The same as any other belt/pulley set up .

It's the 'noticeably larger than the shaft diameter' I was trying to get a handle on .

Re: Derbis are pretty sweet.

> Double Trouble Dan Wrote:

> -------------------------------------------------------

> Derbi's are keepers.

>

> Here is my setup in pictures if you want a mild 50+ MPH build.

> >

Mannnn I was tempted by the Gila, but there are so many good PP kits still on the market, and when I saw treats had a Metrakit left, I couldnt help it, stock gearing im in the low 50's, but as Jbot pointed out, the rpm's are a bit high, Ill play with gearing once it gets a bit warmer out here (Ohio).

Re: Derbis are pretty sweet.

Downhill Harvey (OFMC) /

> JBOT Admin Wrote:

> -------------------------------------------------------

> On these older SL is the vin stamped in the frame anywhere?

>

> No vin sticker to speak of..

Nope, not stamped anywhere.

Re: Derbis are pretty sweet.

Totally normal JBOT /

It is stamped on the engine above the tranny, I found it. Good enough for me

Re: Derbis are pretty sweet.

No frame stamp, just the neck sticker.

I had a authentic derbi vin sticker.. up until I threw it out as nobody wanted it for $15.

Re: Derbis are pretty sweet.

Luigi Garzone /

Can anyone who owns a variant measure their decals for me? I made vectors of them to cut for somebody but don't know the correct sizes

need to know sizes of these two decals

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