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2 speed BB

1170 Views 13 Replies 10 Participants Last post by  itsdoable
Anyone ever set up a bike with one of these to get a road gear & a trail gear?

Saw a hand cycle yesterday that had 2 of them on it. Pretty cool; on a regular bike you can shift it with your heel!
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Bigwheel, the 29er proponent outa Crested Butte, knows all about it. What's really cool about it is you can use it with a fixed gear. I want one in the worst way, but am poor/cheap.
Nice, I have just converted to the singlespeed lifestyle this year after 16 yrs. of geared Mtn. biking and I'm not goin' back...
The trails here in Bend, OR are so singlespeed friendly, but my friends kill me on the road on the way to the trails with the 33x16 setup on my Surly...
I would love to here more from people about this setup because I'm hoping to have a 29" Vulture built this year after I sell the Heckler, and this seems like a nice option to consider.

Jefe' (Bend's dirtiest Acupuncturist)

worldpiste said:
Anyone ever set up a bike with one of these to get a road gear & a trail gear?
I rode one on a 29er at Interbike. The heel-shift is pretty cool once you get the hang of it. The only drawback is that you're stuck with whatever ratio they build into it, but you could always adjust that via bigger/smaller cogs. I just remember that neither of the 2 gearing choice felt "right" for what I was doing at the time (dirt & gravel demo lot, singletrack). IMO a great SS/fixed option for the road.

Never seen one of them in person, but here's my 2 speed with a "get to the trail" 17 and a "trail" 21 cog. Up front is a 32. Wheel size is 700c with a 2.1 Nano up front (KM fork) and a 44c Moto in the rear. The frame is for small wheels but I releived the c/s and s/s bridges to fit the 44c Moto.

Shifter is an old modified Suntour thumb shifter with Double-U Tee Bee adapter.
1 in RBR classifieds (cyclecross)

I just saw one in the classifieds at RBR.


Seems pretty cool

here is a link to Sheldon Brown disscussion of them.

Would be cool to go super over kill and mate this with a Rohlf speed hub.
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bulC said:
Bigwheel, the 29er proponent outa Crested Butte, knows all about it. What's really cool about it is you can use it with a fixed gear. I want one in the worst way, but am poor/cheap.
Are you sure about this FG business bulC, cuz that's actually what I was wondering. On their website it says "no" on the fixed gear application, but OK for coaster brake. And I assume it would be fine for SS too
I've had a speed-drive for a few years now, originally bought it to convert a SS into a 2-speed. I wanted a ~2:1 ratio or general riding, and a lower gear for climbs, skinnies, stunts, technical sections, etc... Schumpf make them in either a 2.5:1 step-up or step down, or a 1.65:1 step-up. Ideally I would have liked to get a 2:1 step-down gear.

The unit is nicely made, heavy but sturdy. The smallest regular chainring is 34t, but you can get a special 27t.

I ran it on my trail bike (converted SS!) for a few years, and it worked fine. However, there is some play in the clutch which is built-in to allow it to shift properly, and it makes ratchetting more difficult - alot of play before the wheel engages. Shifting is easier with the old non-low profile strait arm cranks, it's harder to hit the button with your heel on low profile crankes. Strait crank arms are only available in 170, unless you can score some old RF Turbine strait crank arms with the removable spider. Sometimes you accidentally push the button when you are manuvering the bike in technical sections. Depending on the unit, you have to modify the BB (45 deg chamfer) so that it can transfer torque to the frame. You hit your ankle on the crankarms alot more with non-low profile cranks. There's a slight but definite energy loss feel when you are in the step-up gear.

Schumpf said NO to fixie use with my unit. I think the play in the clutch would be a pain.

In the end, I moved the cranks over the the road bike, and returned the trail bike to SS. It works and feels much more natural on the road than on trails.

PS: Rohloff does not need this, the gear range is wide enough - unless you are on a recumbent...


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The ratios don't work out too well.

Let's say you want to use a 2:1 offroad gear, nominally 52 gear inches. Run that thru a speed drive @ 1.65:1, and you end up with an 86 inch road gear. That's pretty steep for SS on the road.

Try the mountain drive (2.5:1 reduction) with a decent 72 inch road gear, and you end up with 29 inches on the trail. Spin, baby!

You're better off with 3 or 4 tooth difference freewheels on a flip/flop. And you can buy something nice with the $500 left over.
Thanks for all the feedback Tom.

Yeah I run the Sclumph bracket drives. I run a mtn. drive in conjunction with a 7spd (sorry for the sacriledge) on one bike pictured here,

and have a speed drive on another bike with a 9spd. I didn't like them as a 2 spd, but a few others here have them and like them just fine.

They have proven to be pretty bombproof. There are a few special tools needed to get them setup and apart also. I will probably keep using them for my needs for some time to come.

I built the bike in that ad and sold it last year....Fixed gear use is not an option according to Florian, also use at temperatures below 0 degrees F can be a problem.
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Very Nice

Bigwheel said:
Yeah I run the Sclumph bracket drives. I run a mtn. drive in conjunction with a 7spd (sorry for the sacriledge) on one bike pictured here,

Very Nice! Let me know when you sell that one.
I'm wondering if I could live (go faster racing) with the 1.65:1 . Ideally, I'd have a SS-style gear that gets me over every hill in the race course, as I'm SS riding now, but also a larger gear for the flat and DH's. I like 34-17/18 for most Dutch courses, but the long straights kill me, as I'm a heavy fast rider normally. 1.65x longer than 34/18, that's LONG. At 15mph I'd go from spinning to pushing, but hmmm, so cool!
Bigwheel, how would you rate the energy loss in the gearing system? Noticable, or not worth mentioning? Would Speeddrive mean that there's no loss in the lower gears, as it's direct drive?
Uh-oh...from their website : "You need a 45°-milling cutter for installation". Sounds scary.
Unfortunately only shorter crankarms available. I'd be really confused by now had they offered somehting over 180mm. This system sounds like it could be faster than a derailer setup, if a course is too flat for SS'ing to be so already. I should look into 3-speed rear hubs once.
Cloxxki, I ran my 2-speed as a trail bike, 34:26, so I had a 2.16:1 high gear and a 1.3:1 low. Because you have 2 gears, you should 'bracket' what you are using now, since the SS gear is a comprimise between spinning out on flats and stalling on hills. Most smooth trails could be run with the higher gear, and when the slope got too steep (or long) then I'd drop into the lower gears. The low gear was good for the rock gardens too. I thought a 1.65:1 step in gears was pretty good for trails, but I would have prefered the high gear to be direct drive, as there is a small but noticable loss though the gear train. IMHO - my uninstrumented experience, my Rohloff hub gears "feels" more efficient than the speeddrive.

45°-milling cutter: not a big issue in reality, standard BB's can still be used after you have chamfered the BB shell, and most BB shells on aluminium bikes have a small chamfer already. The chamfer just needs to be big enough for the torque transfer ring to bite into.

Cranks: takes standard square taper cranks, but you need to find a spiderless driveside. However, you can use 2 left cranckarms, and swap the axle in the right pedal. However, the BB is designed for non-low-profile crankarms, which are not the easiest to get. Low-profile arms will work, but the pedal stance gets pretty wide. I found some old 175mm RaceFace Tubines (pre-LP versions) with a removable spider in an lbs junk bin that worked fine.

3-speed hubs: I've tried several 3-speed hubs (Shimano/Sachs/SRAM), most didnot hold up to mtb'ing. I currently still have a SRAM Dual-Drive 3-speed disc hub that is working, but Bob (RedHaze) broke his last year, and I'm expecting to do the same eventually. The Speed Drive appears to be mtb-able. The Rohloff is the only one that is really designed for mtb-ing.

Dotek (Taiwanese) was advertising a 2-speed crank, and I was trying to get one in to try out (much cheeper than Schumpf) but it never made it into this country (Canada). Probably a good thing, I would have broken those too...


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