Comtech wheels versus soapbox derby wheels

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Comtech wheel or soapbox derby type wheel?

Comtech wheel
2
100%
Soapbox Derby style wheel
0
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Total votes: 2

vendingsol
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Comtech wheels versus soapbox derby wheels

Post by vendingsol » Wed Apr 06, 2011 9:54 pm

A question to all of the experienced cubmobile builders and racers:

Which wheel is faster, a Comtech wheel or a soapbox derby type wheel?

The soapbox derby type wheels are made specifically for these gravity races so I would think they would have the right type of bearings and design. Also, the skinny wheel would have less rolling resistance on the ground compared to the wider comtech wheel?

In our area, Oak Lawn Il, the fastest cars all have used a RWM Caster brand wheel. Last year was my 1st year with my scout and we used roller blade wheels (thought they would be good as the bearings spin so easily), but we were easily beat by the RWM wheels. Looking to go faster this year and hopefully convince the governing body to let us use a body like jsta6 has, (TOTALLY KILLER AWESOME LOOKS!!!!).

Thanks for your input!!

Scott



DenDadBob
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Re: Comtech wheels versus soapbox derby wheels

Post by DenDadBob » Wed Apr 06, 2011 11:20 pm

Our District race rules require wheels be no larger than 10." I think soapbox derby wheels are too large. We have had great success with comtech wheels.



dna1990
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Re: Comtech wheels versus soapbox derby wheels

Post by dna1990 » Thu Apr 07, 2011 10:26 am

Cost. Unless you find some used ones still in fair shape, a new set of SBD wheels are $110 ish. I think the Comtechs are closer to $40, if I remember.

Yes, SBD Z-Glas wheels are 12", check your rules if they would be allowed.

I liked the bearings in the Comtechs, however, I didn't think the treads (rubber) held up good for us. Maybe on smooth concrete, but after racing a while on asphalt parking lots...they sure seem to get pitted like.

True, the tread contact for the SBD is slightly smaller than the Comtech, but not really by that much (eyeball guess). I am no physics type, but one would think the larger diameter means slower initial rolling resistance. But if you have a steep ramp and a 'long' flat track planned, SBD wheels could gain this back with more flywheel inertia and the smaller tread footprint. I would armchair-guess on a short track, Comtech would win, all other factors equal.

Also, don't assume SBD wheels have great bearings. They don't, sometimes you can get a real dud.

Like PWD, don't forget the lube. Krytox or NyOil can be used pretty well (again check local rules).



vendingsol
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Re: Comtech wheels versus soapbox derby wheels

Post by vendingsol » Thu Apr 07, 2011 1:59 pm

The Comtech Cubmobile kit is $32 plus shipping for 4 8" wheels, 8 paintable spoke covers, 4 paintable hubcaps, 4 6" lag bolts and 8 washers. They have a larger 10" size also available. Are the bearings sealed in the comtech wheels and if not do you lube after each run? Which is most popular, 8" or 10"? Thanks



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