The Unofficial 'CroMotor' Owners Tech-Tips Thread

[gensem]

As promissed..

Wheel is dirt because it was parked for some time.

[Alan B]

Wonder if JRH would be interested in getting a boxfull of them...

The 2.5's are the size I'm planning to use. Those tires look good!

[dangerzone]

Yes, they are 9g... and they are motorcycle spokes (UCP, not stainless steel), as far as I can tell regular bicycles use 15g-13g spokes. JRH has 12g spoke but I think you would need a washer in the cromotor flange.

8 G / 4mm
9 G / 3.5mm
10 G / 3.2mm
11 G / 2.9mm
12 G / 2.6mm
13 G / 2.3mm
14 G / 2.0mm
15 G /1.8mm

Yeah, that will be good, I think it might even withhold some slight off road fun trails or riding up/down stairs... Yet your bike would need some really good rear suspension for such rougher fun.

[dangerzone]

Hah! I have relied on them at 100km/h commuting for about 8000km and they have been fine; 18$ Tioga 1.95's with about 90$ worth of tube kevlar tape and rim tape inside it. I would expect them to burn on the race track with tight turns as you say.
What I meant was that there has been a trend just recently of using these moped rims and mbike tires; they look totally badass and I'm having trouble enjoying the look of kenda flames or holle rollers the same way. There is no doubt these are safer, maybe cheaper, but heavier and won't fit every frame; bike tires have been getting a bad rap as we push these things faster, but what Luke does with his 3-400 pound "bike"+rider weight on the track is not comparable to many other peoples situation. If you are running a hub motor on the street as a commuter I would be upgrading to get the stronger rim, not the stronger rubber, but that's just me; I have found the rim to be the week point in my hard tail builds, with a DS bike I wouldn't even be worried. Is there ANYONE besides Luke that can really say they raced their ebike to the point that the side walls of their tires failed? I will take my hat off to them as well, for I am in awe.

Well, I have been riding bikes for some time and motorbikes are something completely different than bicycles when it comes to handling. Even after a few weeks of riding motorbikes when you sit on a bicycle everything feels weird, too light, to clumsy in a way... I did try to lean with a bicycle quite a few times only to find that the rubber of the tires is the weakest link, it does not hold as good as the rubber of a motorbike tire in tight turns. Then there's the problem of bicycle tire sides which are not made of softer material as motorbike tires are. I'm just saying that I would always feels safer with a good (soft) motorcycle tire on my wheel than a bicycle one with the Cromotor in the rear hub. If some cyclists have different experiences I would surely like to know their technique or some tips&tricks...

[johnrobholmes]

I would be interested in a box of them, but if I'm gonna get a box I want a deal


Here is a wheelset that is shipping out today to Canada. On the cromotor I used 108mm 12ga spokes with brass washers under the heads, 17" rim with erd of 420mm, and Gazelle 2.5" moped tires.

[dangerzone]

Order placed for the 11/12 butted spokes in straight pull and 90 degree heads, it will be about 6 weeks now. We also have larger 6mm body nipples coming for 12ga and 13ga spokes to adapt to anything we need.


Here is a little wheelset that we put together for a fella in Canada. Thanks for the build, it is a nice wheelset you have coming!

17" moped rims and Gazelle tires. Should be a blast!

Hey John Rob Holmes, this wheelset looks really tidy and neat.

Yet I do have a question about the lacing on the rear wheel. You laced the front wheel as it usually is laced, every second spoke is laced from the inside to the outside of the hub. But on the rear hub all of the spokes are laced from the outside to the inside, you can see all the spoke head butts are facing towards us. Now, most of the bikes have it one-in-then-the-other-out system to avoid spokes grinding onto each other, like on the front wheel. IS there a particular reason why you laced the rear wheel that way or was it a question of design..? It sure looks extraordinary.

Gensem, I do have a question about the longer spokes that you used for the first setup, which ones are those, looks something like 150mm and 3mm..?



I think that there might be some old Jawa spokes that could be angled to fit without bends. I just haven't got the motor with me to try to put it in a 17' wheel rim, but will try some more options once I get it. I was just wondering how long and thin are those spokes on this picture..?

[johnrobholmes]

The rim I used is fairly narrow (for 2.25 through 3" tires). If the hub was shorter or the rim had wider hole spacing I would use regular alternating patterns more readily, and I actually did this on one of the cromotors. It was a bear getting the spokes seated and set, so I opted for all heads out (inbound spokes) on this build to keep from fighting the outer spokes so much. Another issue with lacing alternating is the inbound and outbound spoke lengths are not the same. It is possible to build either way, and either way will build a suitably strong wheel.

I would recommend an extra 2mm length on the heads in (outbound) spokes if you choose to alternate the pattern in a 17" rim.

[gensem]

I dont remember the length because it was an off the shelf spoke, but it should be something 140-150mm space and it was 3mm.
Btw that wheel no longer has a 2.15 rim and 2.75 tire. I has now a 1.4 rim and 2.5 tire.

[gensem]

2.75 tire vs 2.50 tire laced to cromotor.

[neptronix]

2.75 tire vs 2.50 tire laced to cromotor.

Thanks for the size comparison. I think the 2.5" is definitely enough for most standard bike frames.

[gensem]

Neptronix, using the same 17 1.40 rim the 2.75 wouldnt fit in most regular bikes. But I wont deny it looks alot better with 2.75, looks really pushy.

My caliper is telling me that the 2.50 tires has 2.6inch diameter and the 2.75 tire has 2.90inch diameter.

[GCinDC]

[gensem]

Thats a really long drop out, I would dare to say too long, for the stuff i saw in your videos... but that was a reminder to be carefull with my catapult.

[zombiess]

Thats a really long drop out, I would dare to say too long, for the stuff i saw in your videos... but that was a reminder to be carefull with my catapult.

Just wait to you see what I have my friend fabricating for my exhibition of acceleration bike.

This is what I have now


Rides nice, corners great and that swing arm is extended 8 inches. Problem is I can barely run any phase amps into the motor at 125V because it doesn't matter how far I lean over the handle bars, it will loop me off on a hard launch. New version is most likely going to be 16" or 20" longer with a different shock mount so I can use a longer shock with a stiffer spring I already own vs this very nice 140mm Cane Creek Cloud 9 air shock so I can go hunting just about anything from a dead stop to about 50 mph Should be scary fun.

[fractal]

nice!!!!! can you provide any details???

[GCinDC]

dbaker is the man for details.

all i can say after testing it is:

and his old 24s pack was sagging hard.

[patrickza]

Thats a really long drop out, I would dare to say too long, for the stuff i saw in your videos... but that was a reminder to be carefull with my catapult.

Just wait to you see what I have my friend fabricating for my exhibition of acceleration bike.

This is what I have now


Rides nice, corners great and that swing arm is extended 8 inches. Problem is I can barely run any phase amps into the motor at 125V because it doesn't matter how far I lean over the handle bars, it will loop me off on a hard launch. New version is most likely going to be 16" or 20" longer with a different shock mount so I can use a longer shock with a stiffer spring I already own vs this very nice 140mm Cane Creek Cloud 9 air shock so I can go hunting just about anything from a dead stop to about 50 mph Should be scary fun.

How have you guys managed to mount your disc breaks? With my bb7's and 203mm rotor there just isn't any clearance for the inside of the caliper...

The way I see it I have two options. Either use a spacer, or try to find a 10inch rotor. I like option number 2 more, anyone know where I can buy a 10inch rotor?

[Alan B]

The local hardware store has 10" rotors. They have a little extra material you need to remove. Check in the table saw aisle.

[hillzofvalp]

I'm thinking about water jetting my own disc if I run into this issue. will any faced 1/8" stainless do the trick with enough support?

[zombiess]

My 203mm rear fit fine with my Hayes Trail but it's really close. All my stuff is done custom, probably not as much issue on a normal bike. Avid Juicy calipers are much smaller.

[Lavolta]

Here is CroMotor number 9 laced into an excell 19" rim.

I was planing to only use a 180mm rear disc with Hope 6Ti caliper but it is too wide.

DSC_0202.jpg

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Cheers
Bruce

[andreym]

If you have only 135mm of dropouts and still want to fit some torque arms inside, you can use the following disk rotor adapter mod:
-remove original adapter,
-get avid g2c2 203mm rotor
-get magura gustav M rear brake for enough clearance
-dremel a bit of avid rotor to make it fit and screw it up INSTEAD of original adapter

here is your additional ~5mm clearance for torque arms with CroMotor and 135mm of dropouts!
and some pics:

[MadRhino]

Here is CroMotor number 9 laced into an excell 19" rim.

I was planing to only use a 180mm rear disc with Hope 6Ti caliper but it is too wide.

DSC_0202.jpg

Cheers
Bruce

Nice wheel, have you measured its weight, complete as shown?

[gensem]

he is using thin spokes... so I would guess around 14-15kg

[MadRhino]

he is using thin spokes... so I would guess around 14-15kg

He's using heavy rim and tire, I would guess more than that.