Need help with DH bike w Cyclone freewheel BB setup

[lesdit]

OK, I've got a rather odd e bike setup that I'm working on, and I need a bit of bike tech help with the bottom bracket.
The bike has a 83 mm bottom bracket shell width, which had a Shimano hollowtech 2 bottom bracket and crank set in it. I have a cyclone 1200 kit that came with a 135mm length taper spindle and some aluminum cranks.
Now here is where I am confused because I am not very familiar with bike parts in general : Can I just get a bearing kit for the cyclone supplied spindle and fit it to the BB shell on the bike ? Since this DH bike has a rather wide shell, will the bearings 'reach' the races on the cyclone spindle , which are about 56mm apart ?
The funny thing is that the extra length spindle that came with the cyclone kit puts the cranks and pedals at the same spacing as the original shimano hollowtech 2 setup the bike had originally!
I don't mind using the old school taper spindle if it can be made to work, but I'm just not sure if it can be used, since it was a generic type of kit that wasn't designed for down hill bikes with their oddball sizes. Any advice from bike savvy mechanics would be greatly appreciated. I have access to a machine shop, if that is needed.

 

[flyinmonkie]

The spindle from the kit is designed for an older non-cartridge type bottom bracket. You can find kits to retro fit it to your bike, but they can be hard to find. If the cranks are already at a width that clears the motor, then I would leave the current cartridge bottom bracket in. It is stronger and easier to maintain than the old school bottom bracket and the spindle and cranks with be stronger as well.

FM

 

[deecanio]

hi Lesdit,

Im no bike mechanic but i hope this helps.
im not sure about adapter kits but look there first, that would be easiest.
If you get stuck or its looking like anymore than $100 you could always keep your standard bb and just get some new crank arms to match, is your current bb isis?
i had a similair issue with mine, the kona is 68mm bb width, i think, but i just got round it when i bought an isis bb by getting the 73mm width one that came with a spacer for 68mm.
i'm not sure if you will be able to buy a 83mm width square taper bb, i think their too far apart in terms of age to get one but don't panic there's always a way :wink:
When your looking into it don't forget to check the bb spindle length also, you need as wide as you can get to give you every chance with crank arm clearence, i used 128mm - the biggest i could find and it saved my bacon.

Best of luck with the build, pop up some pics and shout if it doesn't make sense


**EDIT** i just re-read and i see that the cyclone came with a 135mm spindle length that must be for the motor clearence ? still i think you may be able to get away with 127/8 - it will depend on the angle of the crank arms.mmmmm.
Post up some pics so we can see what we're looking at.

Cheers,

D

 

[lesdit]

Thanks guys. I would like to use the current BB, but the issue with that is that it is a hollowtech 2, and those have the spindle integrated with the right side crank assembly. The parts look like that came off of a NASA project, I'm impressed how far bike parts have come since I last tinkered with bikes!
So I'm thinking the only way to use the Cyclone square taper spindle is to cut it in half and extend it with a piece of Chrome moly tube in the middle, to get the bearing races out further, unless there can be some kind of spacers that push the bearings inside the 83 mm BB .
This is quite a mess. I might have to make my own spindle. I did expect a lot of issues with this modern bike, so I'm not too surprised, it's just a bit frustrating because I don't know bike parts very well. The choices for sprockets and spiders that support them will also be tricky, I'm sensing.
I do have a machinist I use for work, but I hope I don't need to get into CNC parts, that gets expensive. I'll try to post some pictures, it's a fairly exciting project converting this bike, a GT it1 , as it has what they call an 'internal transmission' , which is nothing more that a Nexus 8 mounted right above the BB. 9 inches of suspension travel and the rear wheel weighs about the same as the front wheel, as far as sprung weight goes. I am going to spin the Nexus faster by re gearing, so i suffers less torque, hoping to keep it alive longer :wink:

 

[GGoodrum]

One issue is that the crank arm that comes with the Cyclone kits uses the square taper, not the ISIS, so if your cartridge BB doesn't have the square taper ends, What I would do is see if the left crank clears the motor case. If it does, what you can do is get a set of Echo trials cranks, which you can get to fit with either square taper or ISIS. You can find them here. These will screw right into the Cyclone freewheel.

If you are planning anything more than a commuter with this build, I would highly recommend that you replace the cheap Cylone FW. White Industries now makes a version of theier high-end ENO that is a drop-in replacement. You can find these here. These are the best there is, period. The Cyclone FW won't last a day on a real DH setup/

The other alternative, for high-power setups, is to run a second chain directly to the rear. This also has the added benefit of separating the pedal ratios from the motor/drive gearing. I'm currently working on a new setup for my Cyclone 1000W kit, which uses a jackshaft to drive a dual sprocket mod I did for a Nexus-3 hub. I'm using a heavy duty ENO on the jackshaft, and although I still need a freewheel on the pedal cranks, since it is not carrying the main motor load, the cheap freewheel is fine. Here's what the dual sprocket mod looks like:




Take a look at Matt's PK Ripper thread. He's not using a geared hub in the back, but he is using two chains to the rear. He has the motor(s)/drive assembly positioned on the downtube in a way that the drive to the rear goes around the bottom bracket. I'm pretty sure I've seen pics of similar Cyclone mounting positions.

Anyway, food for thought. I agree with D, post some pics and you will probably get even more ideas. Lots of clever people here.

-- Gary

 

[lesdit]

OK, those trials ISIS cranks are looking good, and I can get 83mm shell size ISIS bottom bracket kits. I will still have to extend the spindle to 135mm , but since the ISIS spindles are not integrated, like the hollowtech's are, I can more easily mess with an ISIS spindle without jeopardizing more expensive parts if I screw it up. ( does anyone sell ISIS spindles that are 135mm ?? ) . This bike is certainly not a commuter, a DH bike would make a poor choice for that. Who needs tons of suspension travel for a commuter anyways? The DH bike rides like a pig without a motor, feels like riding a pillow around! But with a motor, it should make for a capable off road machine.
I really want to drive the transmission with the motor, to be able to downshift for tricky rocky or sandy single track routes, and upshift for more fire road like conditions.
On the freewheel, is it true that the white bros. unit is a single ball bearing construction, and tends to have a bit more wobble than the ordinary freewheels that actually have dual bearing races ? I thought I read that someplace.

 

[12p3phPMDC]

Lesdit

A nexus 8 electric transmission huh? wow! that'll be interesting...
305% range. Do you know what you input reduction to the nexus 8 will be?
In bottom gear, that's almost a 2:1 (1:0.527) reduction.
Sounds like you want a serious reduction.....lots of torque...yikes!
It'll be a great test of the nexus 8.

Gary,

any problems with the spring clip retention on that custom dual sprocket bolted to the three spline hub input on the nexus3?
Did you balance the sprockets in a sandwich of the Sturmey three spline sprocket?

 

[Miles]

On the freewheel, is it true that the white bros. unit is a single ball bearing construction, and tends to have a bit more wobble than the ordinary freewheels that actually have dual bearing races ? I thought I read that someplace.

Yes, single sealed bearing unit on one side, ratchet and pawls on the other - so it's not ideal for running power through it in 'freewheeling' mode...

 

[flyinmonkie]

Lesdit,

Pics Pics... I have been looking for that bike to convert because of the integrated "gear box" myself. It will be cool to see one done. You could always look at driving the "gear box" from the motor and skip driving the crank all together. That way you can pedal with the motor if you want and it save the trouble of making a freewheeling crank. I have done that on my chopper bike. Here is the tread http://endless-sphere.com/forums/viewtopic.php?f=28&t=8492

Not sure if there is enough room in the back for a cassette hub but that could be the answer and run it as a single speed with the pedals and geared with the motor. Or try to set up a dual sprocket on the hub with a freewheel for the pedals. There's always more than one way to get the final results you want.

FM

 

[deardancer3]

I had one of those challenges once- Too wide a bottom bracket shell for a cyclone BB axle.

I slimmed the shell down with a special grinder under supervision at a good bike shop.
(You have to get the math right about how much metal to remove from each side). It was an aluminum bike so grinding went fast, way too fast at times and keeping it straight and flat was a challenge.

but it worked just fine after that.

d

 

[boostjuice]

The longest spindle size you can get for 83mm shell bottom brackets is 128mm.

I would suggest either of the following options;

Buy some ISIS freewheel crankarms (Echo etc) as well as a 100mm shell width Bottom bracket which has a spindle length of 145mm~148mm (This rare size is used in a few select DH mountain bikes).

Using Headset/SS hub spacer rings (1-3/8" inside clearance fit), pack out the lipped threaded BB shell sleeve that overextends your frame shell so it can be seated thrustwise during tightening.
You can minimise this packing width by using a dremel to remove about 5mm of un-needed material from inside the base of these threaded sleeves that retain the bearing shell into the frame shell ( i have done this myself). This brings them inward and reduces their unsupported overhung loading by placing more of the threaded section inside the frame shell.

You can then install your freewheel cranks and enjoy the 5mm extra clearance either side of your gearmotor barrel and crank arms (145mm ISIS spindle vs 135mm Cyclone spindle). The sealed bearings of the ISIS BB will outlast the cup and ball oldschool style.


Or, if you dont want mind permanently altering your frame do as suggested by 'deardancer3' and narrow your frame's BB shell and fit the cyclone cup and ball spindle. You will also need to re-thread/re-tap the cut down shell so the bearing sleeves dont bottom out on the less deep frame shell threads. This will cost significantly less than the other option.

making up a custom spindle is not worth the effort. ISIS splines and square taper ends are too complex to machine in acceptable time and cutting and extending an existing spindle is unlikely to be strong enough or run true.

 

[lesdit]

boostjuice, thanks for that advice. I didn't know they have the 100mm size! How about this one :
http://aebike.com/page.cfm?action=details&PageID=30&SKU=CR2183

Your description of the spacers will probably make more sense to me when I see how the ISIS spindle is actually located in the bearings, preventing it from sliding in and out.

Looks like I won't be using much from my cyclone kit BB, maybe I can use it on my downtube folder bike... :wink:

I was entertaining the idea of not freewheeling the darned thing, and make some kind of pedal torque feedback sense that would just modulate the throttle so the pedals would not spin like an egg beater if my feet came off the pedals, but then I would loose that motorcycle feel going over tricky things , where you don't want to pedal at that exact moment.

I'll take some pics in the next day or so. I have to figure out the way I will mount the extra chainring to the custom CNC'ed GT chainring. The unique design of this bike is going to make it a bit of a challenge.

 

[boostjuice]

Your description of the spacers will probably make more sense to me when I see how the ISIS spindle is actually located in the bearings, preventing it from sliding in and out.

Not quite what i meant....Hard to explain clearly without a picture so here you go mate

The second drawing down is the rough dimensions without dremeling out the BB threaded sleeves. If you were to dremel (as shown in 4th drawing down), the spacer ring would need to be narrower to allow the BB threaded sleeves to be screwed in further. Again, the advantage to dremeling is that there is more mating surface area between the threaded sleeve and the frame shell.

 

[lesdit]

OK, I see what you are talking about better now, Thanks !
Could I also take the silver middle part and use a lathe to remove some off the ends , letting the red parts be closer together?

 

[boostjuice]

OK, I see what you are talking about better now, Thanks !
Could I also take the silver middle part and use a lathe to remove some off the ends , letting the red parts be closer together?

Well, not with the bottom bracket i am using (FSA Platinum DH). My one has the bearings seated almost right at the edge of the silver part (bearing retaining shell), however other makes may have the bearings set back further into the bearing retaining shell allowing you to do that.

 

[lesdit]

Ok, ordered the echo cranks and the 100mm ISIS bottom bracket. Called GT to see what other sprockets I may be able to get from them, but they are all in a sales meeting in Colorado this week. Thanks for the advice.