Has anyone tried the SRAM Dual Drive alongside The SBP Shift Kit?

Discussion in 'Frame Mounted Engines' started by Neon, Mar 9, 2010.

  1. Neon

    Neon Member

    I tried searching the forums for this but came up with nothing. I was wondering if this would be the ultimate setup for gearing or would it be just a waste of time and $300.

  2. Hawaii_Ed

    Hawaii_Ed Member

    It seems really nice, my understanding is it goes higher and lower than a standard casette does? I can say with my 8 speed rear, I rarely hit 8th gear unless I am down hill and flying. IMHO the DD SRAM is more gear than you'd need, a simple 8 speed works great.
  3. Neon

    Neon Member

    Thanks for your reply Hawaii_Ed. Your feedback means a lot. I kinda figured it might be a little bit of overkill. But it might be fun to get the feel of driving a Transport again with low, mid-range, and high. Now if they just made a small diesel that was light enough i'd be in heaven.
  4. Hawaii_Ed

    Hawaii_Ed Member

    Are you a military driver? LOL. Running a veggie-diesel bike would be great!

    Realistically, 45 MPH is my cruise speed, that is a decent rpm in 7th gear. If I hit 8th, I lose speed unless I am behind a truck, tail wind, or down hill. The power band in these engines is pretty high and narrow!

    If you have the cash, why not :) More is always better!
  5. Neon

    Neon Member

    Not a military driver just an ex transport mechanic that had to rescue a few rigs. One of the nice things about a diesel is as long as it is oily it will burn it. Not so sure that the common fuel rail system will take anything other than pump diesel though. Never had the nerve to try it. Anyway I have the cash but wasn't sure if it would be worth the effort or if i should give the nuvinci hub a shot like everyone else seems to be doing.
  6. Hawaii_Ed

    Hawaii_Ed Member

    I'd say build it with normal gears, and then upgrade once you get it dialed in. Obviously, I am a fan on the shift-kit. I'd like to try a nuvinci, but I am fine as is.

    I had a dream of building a veggie-mercedes at one point, but I have too many cars!

  7. Neon

    Neon Member

    Not hard to get the veggie Mercedes. Dump in vegetable oil in your tank and advance the timing a hair. Not that i'm trying to convince you to do it or anything but it really is that easy. Actually you don't even have to advance the timing any but it never hurts. And i know what it's like to have too many cars.
  8. Fabian

    Fabian Well-Known Member

    Hi Neon,

    I have thought about the SRAM Dual Drive before, actually i really want to fit one to my motored bike because i never have a 1st gear that's low enough for the hills i need to climb and never have a gear high enough when selecting a front chainwheel that's low enough for hill climbing.

    A SRAM Dual Drive is exactly the solution i want, save for a proper Rohloff hub that's awfully expensive.
    My concern (and it may be unfounded concern) is that the planetary gear drive would blow itself to pieces with the torque put through it from a 9T to 44T Jackshaft ratio and a 30T to 36T chainwheel to cassette ratio.

    If i could be reassured that the Dual Drive hub was sufficiently strong enough to cope with the torque applied to it, my bike would have one fitted tomorrow.

  9. Neon

    Neon Member

    From pictures i've seen of the hub torn apart it looks like it will take a lot of grief. The teardown pictures can be seen at Endless Sphere. I guess the early versions of the hub were not very tough and might last a month. But have since been made tougher. I don't like the idea of being a guinea pig either.
  10. Happy Valley

    Happy Valley Active Member

    Just a comment on this..........
    Fill in the blank above but I see this question come up a lot in relation to MAB engines and components being able to handle the requisite torque from them. These small engines generate almost nothing in the way of torque compared to a 200 lb. cyclist standing up on the pedals cranking up a hill. The point being if bicycle components stand up to heavy duty torquing in cycling tasks they should withstand the few ft. lbs. of torque supplied by a MAB engine.

    I think a more representative question in fitting out components is if they are designed to hold up under the wear and tear of consistant higher ground speeds that motorizing a bicycle usually allows, IE: sufficient access to frequent lubing, etc.
    Last edited: Mar 10, 2010
  11. Neon

    Neon Member

    I don't mean to tick anyone off here, especially senior members of this forum. but i have never seen anything fail because it had been lubed frequently. I have seen things fail when they stop becoming lubed regularly and dirt and other contaminates get into them and start grinding the **** out of them. or they destroy themselves over a lack of lubrication.
  12. Happy Valley

    Happy Valley Active Member

    I apologize if my post wasn't clear and edited to reflect that.
    The point was of course to indeed suggest the implied, increased wear and tear from consistant higher speeds would require the necessary attention to lubrication.
    Last edited: Mar 10, 2010
  13. Neon

    Neon Member

    I apologize myself. I should have been a little clearer from the start. I was just thinking that the dual drive would replace the chain ring, sprockets and derailleur that would have to go when installing the shift kit. And would stop the head scratching over what size of sprockets to use on the front freewheel. Since the hub already has 3 internal gears to choose from. I was also looking for an alternative to the nuvinci hub as i always have to be different from the masses. Torque and lubrication issues were never a huge consideration when i saw pictures of the hub being taken apart. The hub looks internally very strong and well designed.
  14. Fabian

    Fabian Well-Known Member

    Hi Happy Valley,

    I think you're missing the point that i was trying to make regarding the produced torque applied to the SRAM Dual Drive hub.

    Yes, an internal combustion engine does not produce a lot of torque compared to a 200lb cyclist standing on the pedals, "but", a 200lb cyclist does not produce high frequency vibration that the hub must endure.

    I should have been more clear about my concerns.

    Still, a 2 horsepower engine would be able to produce significant torque at maximum power output through the reduction gearing i've outlined in my post, coupled with a high level of vibration that's hammering away at the planetary gear sets.

    Am i wrong in my opinion or have i rationalised the subject incorrectly?
    If SRAM would warranty their Dual Drive hub in a motorised application, it would be on my bike tomorrow.

  15. Neon

    Neon Member

    Hello Fabian

    It's doubtful SRAM would warranty it when used in this application. They don't even warranty it if is used in rickshaws or trikes. Although i've read about many people using them in those applications and not having any trouble with them whatsoever. I even read about a trike that had a total of 81 gears using the Dual Drive.