My new build Forge dual discs & GEBE

Discussion in 'Rack Mounted Engines' started by TWalker, Feb 13, 2009.

Tags: Add Tags
  1. TWalker

    TWalker Guest

    My project: A lightweight motorized bike that works well as a bicycle. Versatile, light and well balanced and it should be a looker. The Sawback is a bike that serious riders would generally take more seriously, it is not a department store bike.

    After long research and searching for a bike I really wanted I came up with this solution. A Forge Sawback which is a phenomenal bike for the price >400 with Shimano Deore components, a great little dirt bike. Basically a Giant frame which would normally sell for about $600.

    A GEBE 4 stroke and a Nashbar trailer. Easily a $1300 setup but it seems good for what I want to do.

    What do you think about a well built aluminum hardtail?
    Vibration a problem for this aluminum frame?
    I'm checking clearances on the rear dropout for the drive ring. it looks good in pics but I need the actual measurement.
    I shouldnt have a problem with the dual discs brakes...right?

    I want it to look slick, work great as a motorbike,work great as a bike when I take the motor off, be light weight with or without motor and be ready for cross country.

    It will be around 40lbs with motor. I originally wanted a freewheeling lightweight bike but there is just no real good solution for that. A center mounted Staton chain drive adds ten LBS and the gear box eats up horsepower. Nuvinci the same thing.

    GEBE looks to be the best way to get horses to asphalt and keep it generally balanced and lightweight. I plan on mounting two fuel bottles opposite the engine to keep a more balanced weight and "look".

    Lotsa info I know but tear it apart and tell me what you would do if you wanted this setup and were going to spend $1300+.


    Attached Files:

    Last edited by a moderator: Feb 13, 2009

  2. jg767

    jg767 Member

    Nice looking bike! You'll have no problems with the disc brakes, you just need beefier spokes and at minimum a 36 spoke rim, to handle the stresses of the drive ring. My GEBE setup went through spokes with the 32 spoke Taiwan made wheel that came stock with the bike( this was a Montague, not a cheap dept. store brand). I bought the Velocity 105g wheel from GEBE, nice wheel but I don't believe they sell them with a disc mount. If you only have a 32 spoke wheel, plan on changing it.
  3. TWalker

    TWalker Guest

    MMM.bad. That would mean doing away with some high quality black wheels and replacing it with something likely heavier and less quality. These wheels have sealed cartridges and they arent cheap.

    I would really really like to find a way to keep them. Worse case scenario I would like to relace them with heavier spokes and reinforce them with ties where they cross. GEBE does have the 32 spoke ring.
  4. kawasaki999

    kawasaki999 Member

    Twalker, Haevy duty spoke is a must! The wheelmaster can re-spoke your wheel with 9 or 10 ga spokes,he did mine for under 200.00. There r very few bike with rear discs that will work with the gebe, usually the caliper is in the way of the brace. This is what it should look like.

    Attached Files:

    Last edited: Feb 13, 2009
  5. augidog

    augidog New Member

    that is one nice bicycle. kevin runs a hardtail gary fisher that looks similar in many ways, but v-brakes rear, sturmey-archer drum front...he loves it. the gebe setup doesn't usually subject a bike to much vibration, thanks to belt-drive with spring-tensioner, along with axle-mounting.

    rebuild those wheels, Wheelmaster would do a great job no doubt, or...

    only 14G, but SS, sealed bearings...

    kawa, that's nice work clearing the "caliper" :cool:
    Last edited: Feb 13, 2009
  6. TWalker

    TWalker Guest

    Turns out this is the bike I got. A high end Cannondale F3000 CAD3. I want to put a yellow Subaru on it. I plan on mounting it to the frame not the axle.

    The drive ring may or may not clear, if not this will be my non-motorized bike.

    I want a super quality lightweight ride. I will consider a DE but I don't want friction drive really.

    Very nice bike, which more or less will be a gift to me. The rear deraileur alone would cost as much as a more expensive Walmart bike. I'd like to do it up right.

    Any suggestions welcome.

    Attached Files:

    Last edited by a moderator: Feb 15, 2009
  7. pumpbuilder

    pumpbuilder Member

    Man thats one nice Bike. Look forward to seeing it when its done with whatever you choose. Always wanted a Cannodale before I went with the Bent.
  8. DetonatorTuning

    DetonatorTuning Active Member

    real nice bike for what it is, but, from the looks of the enlarged pics i don't THINK the GEBE driverin gis going to make it in there.

    hope i'm wrong.

  9. TWalker

    TWalker Guest

    You may be right but no worries, I'm not really set on the GEBE. I've decided I can go two other ways.

    I like the talk of the minimilist approach of a friction drive, perhaps DE, which is even lighter. The main thing I dont like on frictions is the engine hanging so far off the side...its so....lopsided looking. But I have a new Staton GXH50 friction I could play around with.

    Also I might just buy a dragnfly trailer and paint to match and put a cover on it. I have a quick release push trailer now and super fast lightweight pocket bike trailer which is 90% complete.

    Hook the pocket rocket on the back and you will be seeing me post in the top speed thread maybe.

    With a quick release trailer that pretty light weight bike stays pretty, light weight and that nice aluminum frame stays in tact.
  10. I think I could make your stock 32 spoke wheel hold up. useing nine gauge spokes, and I think GEBE makes a 32 slot drive ring, the slots need to be carefully modified to accept the larger spoke diameter. finding 36 spoke wheels is getting tougher these days, but I'm still able to get them (for now).....
  11. TWalker

    TWalker Guest

    I got the bike and it is a beauty, one of my dream bikes! Aluminum/titanium and I can pick it up with one finger. Great thing about is it has magura hydraulic rim discs! These are high end trials bike brakes.

    Measurements for the GEBE work...whew! It was a gamble to order a bike like this and hope the it fit the GEBE drive ring.

    See the pic it easily fits a credit card at 8.5 inches from axle center and even at 9.5. From spoke to frame it is 1 3/8 inches about but we looking at 32 spoke wheels so Im thinking about switching to 36's.

    You see any other problems with this build?

    Attached Files:

  12. DetonatorTuning

    DetonatorTuning Active Member

    give us a pic like that of the dropouts on both sides.


    oh there is one on the other page.

    well, it's going to take an extra long solid axle to get the main mount strap out past the ends of the chain stays, since the dropouts are flat and basically recessed.
    Last edited: Feb 27, 2009
  13. TWalker

    TWalker Guest

    My battery died on the camera but all dropouts have enough clearance. Top, bottom, left or right.
  14. DetonatorTuning

    DetonatorTuning Active Member

    the area right around the dropouts where the axle comes thru IS clear and flat, BUT the seat stay legs are attached to the dropout plates in a way that makes them wider than the plates.

    you will need to adjust the GEBE mount legs to compensate for that and in so doing you will need an extra long axle.

    depending on how much you have to reangle the mount legs so they don't rub the frame and catch the axle you may also need to add a shim between the top of the mount and the clutch/drive/ engine bracket so that the tensioner doesn't drive the belt too far under the drive pulley and cause problems.

    this bike will be great under GEBE drive, go for it.