How to make a V-belt drive sheave

Discussion in 'Rack Mounted Engines' started by lowracer, Feb 13, 2011.

  1. lowracer

    lowracer Member

    I have now made 2 V-belt drive sheaves for 2 different MB's that I run using direct drive without the need for a jackshaft to get the correct reduction.
    One of them is a 26" Mtb wheel & just today I did a 700c (29'er wheel).
    - Start with a spoked wheel that you want to add the sheave onto.
    - Take another wheel of the same size & remove all the spokes & hub leaving just a hoop.
    - Use a hand file & file the non-drive side (left) sidewall of the spoked wheel & one side of the hoop. (rough surfaces are better for the bonding)
    - Clean both filed sidewalls with rubbing alcohol & a clean rag.
    - Mix up some JB Weld & apply to both cleaned up sidewalls.
    - Make sure NOT to line up the spoked wheel spoke holes to the hoop spoke holes. Offset these... (you'll need to drill 4 holes later after its all dry in the spoked wheel between spokes to mount braces).
    - Put the hoop on top of the spoked wheel & line up perfectly
    - Allow to dry at least a full day or longer to insure a good bond.
    - Remove all rim tape before drilling (will need to replace rim tape)
    - Drill 4 small holes on opposing sides of the rim (for balance when spinning) between spokes, to mount 4 small pieces of aluminum stock to brace the inside of the two sandwiched rims at 4 points. I use the existing spoke holes in the hoop so I dont need to drill the hoop. Make sure to remove all aluminum drilling burrs
    - Run nylock nuts & bolts thru the holes & aluminum stock pieces at the 4 points bracing the wheel/pulley from the inside. This will also allow you to still use rim brakes but wiould need to set them up wider. Disc wheels are better since the braking is done elsewhere on the wheels.
    - Depending on rear triangle clearances & hoop width, Tire choices may be limited to narrower tires. I run a 1.25 on the front of my DH MTB Beast. Will probably run a 700x35 on the rear of the other MB.
    Take a look at the pics. I haven't done the bracing yet. Just waiting for everything to dry.
    The Matrix singlewall rim I found worked out real well as a pulley due to the spoke channel being V shaped to match the V-belt exactly.
    If you use 2 deep V rims, you can bolt straight thru the V portion after gluing & avoid the aluminum stock bracing.

    Attached Files:

    Last edited: Feb 13, 2011
    cpuaid likes this.

  2. professor

    professor Active Member

    Good going Lowracer, I never thought the brakes would still work on a double wide set-up. You got me thinking.
  3. lowracer

    lowracer Member

    Some bikes have 3 holes for the v-brake pin & can be mounted accordingly.
    Also, v-brake pad bolts have spacers that can be arranged to move the pad out or in.
    Disc, Drum, or Coaster brakes would work better.
    By mounting the sheave on the rear wheel, the front brake does 80% of the stopping anyow, so its not as vital.
    I use a thread-on hub, so if I run a singlespeed freewheel, the wheel will be offset to the right and the 2 rims are fairly centered. If I thread on a 7 speed cluster, the tire is centered & the pulley is left of center.
    On my lightweight MB, I only run one well set-up front brake.
    Also see my other thread 'BMP Friction Drive Kit converted to V-Belt Drive'

    Last edited: Feb 14, 2011
  4. lowracer

    lowracer Member

    Here are a few more pics of the wheel mounted on the bike with the sheave. Plenty of clearance even with the tire centered using a 7 speed cassette. I havent done the bracing yet, but did cut & file the 4 pieces today.

    Attached Files:

  5. lowracer

    lowracer Member

    Here are some new pics of the drivetrain operational. I get a bit more speed using the VBelt drive than the Friction drive partially due to the slightly taller gearing, but also there is less friction than the friction drive (easier to pedal as well).

    Attached Files:

  6. jander6442

    jander6442 New Member

    +1 for that set up very intuitive. I would say that if your making a hard left turn to take care and not hit the outside if that drive ring it might high side you. Very schweet set up BTW.
  7. lowracer

    lowracer Member

    I just finished making another rim sheave drive wheel out of a Vuelta Deep V 650c wheelset. I removed the spokes and hub from the rear wheel so this one is a front wheel drive unit. It came out better than I expected since there is a huge V-section of rim to drill a few holes & bolt thru for that extra security if the glue bond should fail. Using an MTB V-Brake style fork, the one brake arm needed to be adjusted to the top pin hole & the pad post spacers needed to be re-arranged to give clearance for the extra rim surface. It works well at stopping the bike but looks alittle strange having the V-Brakes not be aligned parallel with eachother. I could take & post some pics of the setup if anyone is interested in seeing it?
  8. lowracer

    lowracer Member

    Here are the pics


    Attached Files:

  9. Chalo

    Chalo Member

    Cool. You could try taking all the spacers away from the sheave side pad and moving them to the outside of the arm. This would diminish your ability to toe in the pad, but you can do some of that with a file if necessary.

    Have you correlated the inside width of any bicycle rims to applicable V-belts?

    24 hole deep rims have become common enough that you could probably lace two of them (in different sizes if that were desirable) to a single 48 hole hub.

  10. lowracer

    lowracer Member

    The narrow 'road bike' rims fit v-belts fairly well, & the singlewall MTB wheels also have a v-channel to fit a v-belt well. I have another MTB doublewall rim pulley that doesnt fit the v-belt well, but it still works perfectly since the large surface area being contacted by just the bottom of the v-belt prevents any slippage even under high torque (Lifan 2.5 98cc engine). Lacing both rims together to one hub would be the hot setup, but for me & my K.I.S.S (keep it simple) way of building things, bonding & bolting works great & is easy to do by anyone. The extra rim attached to the spoked wheel adds strength and I still haven't needed to true my pulley wheels after many miles of motorized operation.
  11. lowracer

    lowracer Member

    Long term update:
    Having built 3 of these 'Rim to Rim' pulley systems & running lots of miles on them, I have a few conclusions.
    - None of the wheels has required any truing. I know the added rim strengthens the whole wheel.
    - This setup works well front or rear but does limit tire selections to thinner sizes.
    Examples- my MTB using 2 MTB rims, the widest tire I can get away with is a 1.5" slick before the belt can rub the tire & cause major problems. I am running a 1.25".
    On the 650c wheel pulley, I use the 23c tire (no coices here). On the 700c pulley, I can run up to a 28c which is meaty enough (long lasting touring tire). I'm sure if I shimmed the 'rim to rim' with another rimwall cut off from a donor wheel, I could run wider tires. I'm very happy running the MTB 1.25" slick on the MTB for $9.00 @ Performance Bike.
  12. ratdoggg

    ratdoggg Member

    I built a double rim years ago for a snow bike and just took the two rims to the welders
    and they just put down a bead here and there and it worked great.. The jb weld thing is kinda scary at 25 mph
  13. lowracer

    lowracer Member

    I use JB weld to get the two rims together & get the perfect alignment before drilling a few holes & bolting them together. I havent had any troubles after a few thousand miles on them at over 50 mph.
  14. i just found this thread today 12/18/2016

    is anyone out there still doing these modifications? I need to do something similar for a manual wheelchair drive
  15. darwin

    darwin Well-Known Member

    Wouldn't electric be a better way to go for a wheel chair? Gas motor might get someone in trouble on one of those.
  16. CrazyDan

    CrazyDan Active Member

    But it sure would be fun xD
  17. Frankenstein

    Frankenstein Well-Known Member

    That would probably depend on if the person building the wheelchair needed to be in a wheelchair or not.

    Those of us with functional legs enjoy finding ways to make them less functional, oddly enough.