Chevym14

So I order a new Tikit a few weeks a go and I have been looking allover the internet for tikit stuff to help ease the pain of the long build time. anyway I found this photo of one and it looks like it has 48 speeds! dos it have a 3 speed hub and 2 change rings, with a 8 gears in the back?

https://www.flickr.com/photos/yokoham...n/photostream/

fietsbob

I expect the ratio redundancies are many.. I do see 2 cables running back to the rear hub.

1960 I put together a 3 by 3 by 3 27 speed ... finding a triple cog cluster for sturmey archer 3 speeds
+ a triple crank. there was cotter-pin axle BB's back then ..

dorkypants

I know someone with an Air Friday that has 81(!) speeds: triple crank, 3-speed internal hub with 9-speed cassette. Sure, there are a lot of redundant gear combinations, but what he was after was ridiculously low low gears (on top the gear reduction already obtained via smaller wheels).

Whenever people on standard (or 650c) bikes complain about not having low enough gears, even with MTB chainrings and cassettes, I suggest they try a small-wheel bike for even lower lows.

fietsbob

Schlumpf mountain drive crank does it for Me .. Brompton, with just a 3 speed hub,
15t cog .. chainring is 54t, kick it into low range and its as if a 21.6t granny-gear was there
(50,20 is even numbers)

and both being Planetary gears double shifts are easily done, slow bogged down in High & 1st on a hill ,
to get the next gear, low range and 3rd .. or at a dead stop.

dynaryder

Yes,the rear hub is a Dual-Drive;a 3spd hub with a cassette on the end. My Speed Pro TT has one,but with only one front ring. On this bike it would be total overkill;many of the highest and lowest gears are simply unusable except in almost unique circumstances. Would've been a whole lot simpler,cheaper,and lighter to just run a wide range cassette and/or a front triple. That bike above was prolly just built as a design exercise to show it can be done.

Dahon.Steve

I'll never understand why Sram does not take the Spectro 5, 7 and make a Dual drive out of those hubs?? The 3 speed hub they are using is HUGE and I don't see why they could not make it work with a hub that has more gears. It would truly shock the industry to see a production bike with 45 or 63 gears.

bhkyte

one sweet bike however!!

fietsbob

Nu Vinci CVR hub + a Sclumpf Speed or Mountain drive would be another way to go.
the hub is a turn the grip till it feels right, kind of thing, Continuously Variable .

then the 2 speed crankset gearing widens the range..

MD , it's a '/, 2.5 Reduction, or HSD, 2.5X Overdrive [27t(67.5)] .. SD, it's 1.6X overdrive..

bhkyte

whats the view on the du vici for a folder> overdrive ratios?

fietsbob

https://www.fallbrooktech.com/node/24 top is 360% of low. 1:1 is in the middle
so 180% above the lowest ratio is the direct gear, the external sprocket combination X the wheel Diameter

Bike Friday will sell The travel Bikes and the Tikit with the hub..

Like I say I have the Mountain Drive in low range It has some serious torque to transfer to the frame,
so It uses a coaster brake like arm and strap around the chainstay, for most bikes, but Brompton,
for those the arm has a Button-knob, it sits on top of the shelf that has the rear fold pivot running through it.

Overdrives, there is less torque to cope with , so the BB shell gets the edge Chamfered, for grip,
then you clamp a conic compressible ring between the chamfered face
and the conic face of their built in BB assembly ..
[a steel ring for Aluminum Frames, an aluminum one for steel frames ]

Now CM Wasson (I got my MD from him) only stocks the Speed drive, with a 34t chainring.. in overdrive it's functionally a 54 ish Tooth
same as the Brompton +% crank uses.

think they probably work better with the BWR 3 speedX 2 cog hubs..

dynaryder

That would be a pretty ridiculous gear range that most people would never need. 1x8/9/10 with DualDrive produces a pretty freaking wide range on it's own. My Speed Pro's 11-26 cassette gives me like a 26-120" range. With an 11-34 on 26" or 700c wheels you'd go up and down any hill without mashing or spinning out.

$325 for the Nu Vinci,$650 for the Schlumf,with tax/shipping that's about a grand just for the gears(and that's not including the cost of the wheel build). That's going to what,double,triple the price of the bike? I'll stick with derailleurs for the weight savings and tool-free wheel changes.

fietsbob

Quick math. 360%, x 1.6 is 576%, a Rohloff on its own is 526%

.. going to the NuVinci Website they did announce they have a QR version, now .. no tool wheel changes .. done..

Tax? I'm in Oregon , we get punished for Income, Feds and State, and Property, County, taxes ,
but Not Sales Tax.

dynaryder

Either setup is a whole lot of money and weight.

Good for them. More money(it's not stock,it's an option) and you still have to disconnect the shift cable. Derailleur drivetrain with discs is just the QR.

fietsbob

Minuses; theres the chainroller near the dirt with any wide range capable derailleur, on a small wheel bike,
still damageable RD,+ it's even closer to the ground..

and the drivetrain has to be spinning to change gears. IGH shifts fine, stopped

No potential to pull the chain tight , and no belt drive option

.. single cog cheaper than cassette spares..

Just 1 thumbwheel & QR to pull the wheel on my pLlama-Rohloff.. short chain tensioner.

bhkyte

Interesting,but main advantage in my mind of dual drive is that's its fully compatable with shimano/sram shifters and brakes.

One misconception about dual drive is that its heavy. I haave posted this on the dahon anniversry bike thread. It weighs around the same as a 27 or 30 speed set up. Just the weight is in the hub,not the chain rings and front mech