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What diameter wheels do most people use? Does having the front and rear wheels be of different diameters affect the performance of the vehicle?

Everything depends on the ratio between your drive axle and your wheel diameter, never solely the wheel diameter.

However, with that out of the way, we've been using Banebots 2 3/8 in diameter wheels with no problem reaching all points according to state rules (with a 6mm drive axle and multiple drive arms along a fixed pivot point to extend the effective drive arm length).

Generally though, smaller diameter wheels = less moment of inertia on those wheels = faster vehicle, but after a certain point the amount of time you can shave off with smaller wheels is insignificant compared to points added for accuracy.

Regarding ratio between front and back wheels - not sure this affects anything as we haven't had any issues with steering variability (mostly because we've never changed out the front wheels). Generally try to keep the front and back wheels within 1.5x of each other so when the vehicle is braking/accelerating, neither set of wheels lose contact with the ground because the vehicle tipped over to one side.

jajefan wrote:Everything depends on the ratio between your drive axle and your wheel diameter, never solely the wheel diameter.

However, with that out of the way, we've been using Banebots 2 3/8 in diameter wheels with no problem reaching all points according to state rules (with a 6mm drive axle and multiple drive arms along a fixed pivot point to extend the effective drive arm length).

Generally though, smaller diameter wheels = less moment of inertia on those wheels = faster vehicle, but after a certain point the amount of time you can shave off with smaller wheels is insignificant compared to points added for accuracy.

Regarding ratio between front and back wheels - not sure this affects anything as we haven't had any issues with steering variability (mostly because we've never changed out the front wheels). Generally try to keep the front and back wheels within 1.5x of each other so when the vehicle is braking/accelerating, neither set of wheels lose contact with the ground because the vehicle tipped over to one side.

I am currently using a 3 inch diameter wheel with a 3/16 inch diameter axle, and I am having trouble reaching the minimum distance and having a good reverse. I am using a normal, single drive arm. Do I need to increase the wheel size?

Zxcvbnm123 wrote:

jajefan wrote:Everything depends on the ratio between your drive axle and your wheel diameter, never solely the wheel diameter.

However, with that out of the way, we've been using Banebots 2 3/8 in diameter wheels with no problem reaching all points according to state rules (with a 6mm drive axle and multiple drive arms along a fixed pivot point to extend the effective drive arm length).

Generally though, smaller diameter wheels = less moment of inertia on those wheels = faster vehicle, but after a certain point the amount of time you can shave off with smaller wheels is insignificant compared to points added for accuracy.

Regarding ratio between front and back wheels - not sure this affects anything as we haven't had any issues with steering variability (mostly because we've never changed out the front wheels). Generally try to keep the front and back wheels within 1.5x of each other so when the vehicle is braking/accelerating, neither set of wheels lose contact with the ground because the vehicle tipped over to one side.

I am currently using a 3 inch diameter wheel with a 3/16 inch diameter axle, and I am having trouble reaching the minimum distance and having a good reverse. I am using a normal, single drive arm. Do I need to increase the wheel size?

There are a couple of options to increase distance
- Increase wheel diameter as you said (this will also increase rotational inertia) *Note that you can eliminate some rotational inertia by drilling holes in your wheels or cutting out parts to reduce mass
- Make your lever arm longer (this may make your time slightly slower, but not by a significant margin)
- Use smaller diameter axles
- Using ball bearings can reduce friction and make it go further

Does your string wind off your axle? This can give you some extra distance from momentum if it doesn't

MTV<=>Operator wrote:

Zxcvbnm123 wrote:

jajefan wrote:Everything depends on the ratio between your drive axle and your wheel diameter, never solely the wheel diameter.

However, with that out of the way, we've been using Banebots 2 3/8 in diameter wheels with no problem reaching all points according to state rules (with a 6mm drive axle and multiple drive arms along a fixed pivot point to extend the effective drive arm length).

Generally though, smaller diameter wheels = less moment of inertia on those wheels = faster vehicle, but after a certain point the amount of time you can shave off with smaller wheels is insignificant compared to points added for accuracy.

Regarding ratio between front and back wheels - not sure this affects anything as we haven't had any issues with steering variability (mostly because we've never changed out the front wheels). Generally try to keep the front and back wheels within 1.5x of each other so when the vehicle is braking/accelerating, neither set of wheels lose contact with the ground because the vehicle tipped over to one side.

I am currently using a 3 inch diameter wheel with a 3/16 inch diameter axle, and I am having trouble reaching the minimum distance and having a good reverse. I am using a normal, single drive arm. Do I need to increase the wheel size?

There are a couple of options to increase distance
- Increase wheel diameter as you said (this will also increase rotational inertia) *Note that you can eliminate some rotational inertia by drilling holes in your wheels or cutting out parts to reduce mass
- Make your lever arm longer (this may make your time slightly slower, but not by a significant margin)
- Use smaller diameter axles
- Using ball bearings can reduce friction and make it go further

Does your string wind off your axle? This can give you some extra distance from momentum if it doesn't

How long of a drive rod did you use? I am currently using a 27 cm drive arm. Also, do most vehicles take advantage of the full 40 cm space available?

Zxcvbnm123 wrote:

MTV<=>Operator wrote:

Zxcvbnm123 wrote: How long of a drive rod did you use? I am currently using a 27 cm drive arm. Also, do most vehicles take advantage of the full 40 cm space available?

I'm using a 22.5 cm drive arm and I have 3/16" axles and 9 mm wheels. As for your second question, from what I saw in my region, most vehicles were long with a couple of really small ones. However, since my region has around 70 teams, I wouldn't say that what I saw is an accurate representation of what most people are doing. Mine is around 39 cm in length.

MTV<=>Operator wrote:

Zxcvbnm123 wrote:

MTV<=>Operator wrote:

I'm using a 22.5 cm drive arm and I have 3/16" axles and 9 mm wheels. As for your second question, from what I saw in my region, most vehicles were long with a couple of really small ones. However, since my region has around 70 teams, I wouldn't say that what I saw is an accurate representation of what most people are doing. Mine is around 39 cm in length.

I'm assuming you mean 9cm diameter wheels lol??


And I'm using a roughly 39cm drive arm with another arm that is also 39 cm which extends the effective string distance to 1.4 times the regular 78cm I would've gotten by not using the pivot drive arm.

Guys, do we really need a new thread for each of these questions? It's getting a bit cluttered.

jajefan wrote:

MTV<=>Operator wrote:

Zxcvbnm123 wrote:

I'm using a 22.5 cm drive arm and I have 3/16" axles and 9 mm wheels. As for your second question, from what I saw in my region, most vehicles were long with a couple of really small ones. However, since my region has around 70 teams, I wouldn't say that what I saw is an accurate representation of what most people are doing. Mine is around 39 cm in length.

I'm assuming you mean 9cm diameter wheels lol??


And I'm using a roughly 39cm drive arm with another arm that is also 39 cm which extends the effective string distance to 1.4 times the regular 78cm I would've gotten by not using the pivot drive arm.

Oops lol. How did you manage to fit a 39 cm drive arm on a 40 cm vehicle? Also, how fast is your run time? Mine for full state distance is around 10 seconds.

PM2017 wrote:Guys, do we really need a new thread for each of these questions? It's getting a bit cluttered.

I totally agree, my exact opinion on the Battery Buggy and Boomilever Forums. Perhaps stricter topic creation rules could be implemented? Like mods would have to approve them, or only users with a certain number of starts could create, though the latter could still prove somewhat problematic.