Strongest clamps for frame mounts

[veloman]

I'm doing some research on the best type of clamp to use to attach my motor to the downtube of the bike frame. It's not a pure round tube, slightly oval.

T-bolt clamp

My brother had one of these in the garage and I tested it out. After tightening it down all the way, this thing is ROCK SOLID. I was afraid it might damage the frame since I can imagine it's exerting a ton of force on the aluminum, but it's a cheap Schwinn alum frame (should be quite thick).

I don't have the capabilities to build my own custom mounts, so I think these may be the next best choice.

On the plus side, they will allow adjustment for chain tensioning, and add essentially no weight. Compared to many other clamps, this style seems to have the most even contact, and therefore the best strength and least likely to harm the frame.

Now to find a good online dealer for these.

 

[recumpence]

Yes, I can tell you from experience, those will work fine for typical loads.

Matt

 

[veloman]

Cool. Yeah I'm not putting out crazy torque. Whatever 700watts is at 450rpms.

My latest build is using my same crank driven system, but this time on a full suspension. Ultimately I will likely add a 9c to the rear for the majority of my riding when I want to be 'stealth'. But the my1018z will kick in on hills so I'm not at a crappy 50 or 60% efficiency.

 

[boostjuice]

Yes they work awesome on oval tubes!!

However, for oval tubes, omit using the shim that fits near the fastener. They don't conform nearly as well to non-round tubes and so will likely damage your frame.

 

[veloman]

Wow dude, what kind of motor/gearbox is that? I've never seen anything like it, it's huge!

 

[boostjuice]

Bonfiglioli, 10.6:1 reduction, 2-stage, bevel-helical, A05 cased gear-unit custom mated to one of the larger Cyclone/Headline motors.

http://www.bonfiglioli.com/en/industrial/products/p/helical-bevel-gearmotors-series/?oid=6

Your right, its pretty big. Very few frames you could adapt it to. However, both motor and gearbox weigh no more than a Crystalyte 530X series motor :wink:

 

[jag]

Here's boostjuice's original build post that match those beautiful pictures. Hope you don't mind me reposting.
http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=7558&p=114161&hilit=cyclone#p114161

 

[D-Man]

So the clamps only have a mount on one side? I only see one nut where you can hook a bracket to.

 

[boostjuice]

Here's boostjuice's original build post that match those beautiful pictures. Hope you don't mind me reposting.
http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=7558&p=114161&hilit=cyclone#p114161

I don't mind. A few things have evolved since that old post though. Both in terms of my knowledge and the bike's specs.

So the clamps only have a mount on one side? I only see one nut where you can hook a bracket to.

Ahh yes, i should have explained that too. I discarded the bolts that come with the clamps and replaced them with sections of threaded rod. I also drilled out the threaded retaining cylinders/barrels so the rods were a slip fit through both sides. That way you can hang mounts off both sides and torque down nuts/spacers on each side individually for fine alignment/adjustment.

 

[veloman]

Ahh yes, i should have explained that too. I discarded the bolts that come with the clamps and replaced them with sections of threaded rod. I also drilled out the threaded retaining barrels so the rods were a slip fit through both sides. That way you can hang mounts of both sides and torque each side individually for fine alignment/adjustment.

Hmm, good idea, I will keep that in mind. I ordered some off ebay.

 

[MitchJi]

Hi,

Yes, I can tell you from experience, those will work fine for typical loads.

Matt

What's a ballpark typical load? 3kw-4kw?

Yes they work awesome on oval tubes!!

This might be expecting too much but do you think they would work with oval tapered tubes like (for example) this Kona downtube?:

Thanks!

 

[boostjuice]

Hi,

Yes, I can tell you from experience, those will work fine for typical loads.

Matt

What's a ballpark typical load? 3kw-4kw?

This might be expecting too much but do you think they would work with oval tapered tubes like (for example) this Kona downtube?:

Thanks!

The idea with any clamp is to maximize the surface area of the gripping contact points. Tapered tubes are a pain but could be approached with these clamps using a soft conforming material such as rubber to spread the load away from the edge of the clamp strap that would otherwise focus the full clamping force along its edge when strapped on a tapered frame. Of course a machined alloy block that follows the exact form of your tapered frame would the 'proper' way to approach your problem, but not doable without craftiness with hand tools or access to machining gear.

As a measure of the clamps strength. kW means nothing, it's torque/force that matters, and how it is leveraged off the the frame clamps. It's too hard to generalize a rating as there are too many variables as every setup is different.
I can say however that set up right, they will do their job well for any drive mounted off a frame.

 

[MitchJi]

Hi,

Thanks for the information boostjuice.

I'll probably avoid a tapered frame but making wedges to accommodate the taper might not be that hard if the frame only tapered in one dimension. Wood might work well.

Thanks Again!

 

[MitchJi]

Hi,

For Round Tubes these might be good:
http://www.mcmaster.com/#vibration-clamping-hangers/=9xmr9c

Vibration-Damping Clamping Hangers

A rubber cushion on these hangers reduces vibration and noise. To close the hanger, insert the head of the included bolt into the slot end for a temporary hold before tightening with a Phillips screwdriver. Hangers have a threaded nut on top for inserting 3/8"-16 threaded rod (not included, see threaded rod). All are made of corrosion-resistant zinc-plated steel. Cushion is black. Temperature range is -58° to +230° F.

Tubing size OD of 3/8" to 2 3/8", rated for 180 pounds, $2.00 or less each.
Tubing size OD of 2 1/2" to 4 1/2", rated for 300 pounds, $2.64 or less each.

Or maybe these:
http://www.mcmaster.com/#vibration-control-clips/=9xn45a

Vibration-Damping Strut-Mount Clamps for Pressurized Lines

Dampen vibration and noise and absorb shock when supporting tubing and pipe in hydraulic applications up to 2,000 psi. Clamps are polypropylene and are secured by dual-clamping bolts and nuts. They are 1 3/16" and fit all 1 5/8" wide strut channel (not included). Temperature range is -22° to +194° F.

For OD up to 4" and about $6 -$12 each (zinc plated hardware) or about (cringe) $40 -$60 each (SS hardware).

 

[Dingo2024]

this is what I used.........

http://eclipsebikes.com/custom-chainwheel-mounting-p-993.html

its an elation based kit (on a cyclone motor) and it seems to work pretty well

it is basically a chain covered in heatshrink with a threaded bar at each end for adjustment and a turn buckle on one side to stop rotation and allow adjustment to the drive chain. The turn buckle uses one of the clamps mentioned earlier in the post around the seat tube

Ian

 

[elation]

Hi All

For the record, the "eclipse" sytem IS AN ELATION system, and people say watch out for China HA.

The motor is a Headline motor which is used by eLation (not version 3) and Cyclone.

They purchased from us as Joe Public and then posted it on there web. I still have emails that passed between us when they got caught out due to some uniqiue aspect of that actual order.

You just have to look at it and see the torsion arm, mount plates, etc are indentical. Please place credit were it is due.

Allan