[patineto]

this is a little off base with the whole freeride downhill thing but for sure a interesting subject, at least for a bike GeeK like me.

basically the problem is that rim brakes on a tandem get super hot when you are going downhill do to the extra mass,but is a few things you can do...get the biggest RIMs you can find since the more surface that is expose to the elements the faster they are going to cool down, a basic thermal exchange, in my case i when with the super oversize trailpimps.

well even then I was looking for more reliable Braking power so i decide to install a set of Disc brakes on the bike,,the main problem was how to operate the two sistems at ones,,
for a few days i play with the idea of ussing a old "diacompe" double wire sistem and run one of the wires to activate the brake pump and the other to the v-brakes,,i know i can be done, some of my old BMW motorcycles use that sistem but was just to complicate and dificult to control modulation..

so thanks to mark (i think is the name) i got some old C2 Hope levers and i flip them upsize down, this way my hands can be place at the end of the bars with out much trouble and since the C2 is a "airless" sistem does not make a diference if is upsize down or right side up...

anyway sorry if this is confussing,,my Ingles do suck

here are the pictures of the diferent possitions.

V-brakes ON

Disc brake ON

the TWO brakes at the same time ,can you say Stooooopies

i don't really like Bar-ends that much but in this case they help to protect the reserviors.

another little trick, the Hose from the Hope brake was getting on the way of my hand so i build a small "bridge" ussing a ziptie and some string rap(vertical line from the bar to the hose) the way is done you constrict the ends of the ziptie with the stringrap (with heat to make them rigid) and then leave the rest untouch so is kind of stiff(you can control how flexible it is by heating more or less of the rap)..works like a dream anyway.

another beauty about the C2 calipers is that is extremlly easy to control the lever travel and the pad engagement by moving the silver knob, so if i'm just riding around i release the fluid pressure and i have NO drag from the disc,,when i need the extra braking power I move the Knob as much as i need(takes 5 seconds at the most) and have extremlly powerful braking

anyway thanks to all you guys,, for the Big-um Hubs the great surly Instigator fork (I hope i don't bend it) the Bash rings,,,etc, i'm sure I will ask for more parts, when i get more money and some other crazy ideas.

here are some more pictures of the almost complete bike (I need to re-weld the post for the rear brake and get a really long hose) before I'm done.

Pretty Evil or What!?!?!?

anyway a little off topic but I hope you guys and gals like the little project

 

[Darkreaper]

Good grief, I can imagine that bumping along some singletrack...

 

[sanjuro]

The rest of us will know what it is like when a hiker sees a rider ripping down a trail at 'em!!!

 

[mack]

Wont that do some damage to those non rim brake rims?

 

[caputo1989]

Wont that do some damage to those non rim brake rims?

dude loook at the rim again they arecompatible with both.

 

[Darkreaper]

The wheel lacing appears strong enough to cope with the forces generated by the discs, although I can't work out off the top of my head how the two braking forces interact.

I would love to ride that thing for the craic...

 

[ioscope]

I think that it would be better for the wheel to have two brake forces, it would spread the load more. I'm no engineer though.

 

[Ruprick]

I'll give you $20 for that hite-rite.

 

[Repack]

A shop near me has a 10" rotor made for a tandem. Magura I think. I have also sen tandems with drum brakes mounted to friction shifters as a sort of down hill cruise control.

Cool setup though.

 

[Darkreaper]

Ruminating further on the two brakes - It probably does help to spread the load by splitting the stress between the v-brake bosses and the disc mounts. Both still on the fork though so you would certainly need a tough headset. You still only have a small contact patch of tyre to give friction against the ground. I wonder could you endo that thing?

 

[Biscuit]

dude loook at the rim again they arecompatible with both.

I don't know for sure.. but I always thought Atomlabs were "disc-only."

That's why they come with shiny, non-machined sidewalls.

You may want to check with Atomic before you ruin a perfectly good wheelset.

 

[Darkreaper]

The Trailpimps will work with rim brakes, although the surface coating will reduce performance somewhat.

 

[Mackie]

I wonder could you endo that thing?

The laws of physics dictate that you would fold the front fork first.
Tooth loss would undoubtedly ensue.

 

[patineto]

The wheel lacing appears strong enough to cope with the forces generated by the discs, although I can't work out off the top of my head how the two braking forces interact.

I chose the Hope hubs because I can have a extreme lace pattern, they are pretty much a "Five" cross.

I'm pretty sure they will be long lasting, i also install brass whasers at the nipple area to decrease the friction and make the nipple less sticky and more able to keep constant tension

About the brakes I'm still getting use to the extreme power but so far they work extremlly well, the ergonomic compromise is a lot less than i spected.

two days ago a got my super dupper long Funn 20MM fork so now is time to really test the true potencial of the brakes since with the QR I was a little scare of a failure or the disc brakes beinga little to powerful and bring the QR wheel out of the drop outs.

I would love to ride that thing for the craic...

if you are ever around san francisco you are more than welcome to try the monster, is for sure a ton of fun and extremlly challenging to ride on the trails,,but hey that is half the fun.

 

[patineto]

I think that it would be better for the wheel to have two brake forces, it would spread the load more. I'm no engineer though.

that is the idea, keep the heat away from the rim as much as you can and alternate dutty with the disc rotor.

 

[patineto]

I'll give you $20 for that hite-rite.

No way....
I have 4 of them for the last 20 years(one is about 25 years old...
glad to see somebody that recognize the "Old school" standard of A^^Kicking..

 

[patineto]

Ruminating further on the two brakes - It probably does help to spread the load by splitting the stress between the v-brake bosses and the disc mounts. Both still on the fork though so you would certainly need a tough headset.

I install a DEEP king headset to decrease the effect of the leverage hopefully that will help, sincerlly i don't know any better,,the Gorilla bearings look super strong but the cup insertion is way to small, will see.

You still only have a small contact patch of tyre to give friction against the ground.

is Incredible to see how the front tyre deform and grip like velcro to the ground,, just in case & fior fun I'm going to run a 3"Gazzy and see what happend, so far not even ones i experience lost of traction,,Fun, Fun, Fun.

I wonder could you endo that thing?

So far i done a few "Stoppies " by my self,,super easy to acomplish with a passanger you can just "Punch" on the brakes and as long the wheels is going forward(not steering) the braking power is incredible more than anything beacuse the mass is located so far back the tyre just dig in on the surface and stop in no time(much faster than a half bike)

 

[patineto]

I don't know for sure.. but I always thought Atomlabs were "disc-only."

That's why they come with shiny, non-machined sidewalls.

well they work lake a dream on rim brakes,,hopefullty the seam does not come apart since the rim is very burly and "Brute" but not exactlly work a of art

You may want to check with Atomic before you ruin a perfectly good wheelset.

Atomic's!?!?!?
I will love to find even better rims for this bike, about rebuilding the wheels I don't care I love making them specially for fun and not for work like I used to..

The Trailpimps will work with rim brakes, although the surface coating will reduce performance somewhat.

I was worry about that, but so far they brake better than a SUP mavic rim(In the dry), i'm also running RED compond Koolstop pads,,
so far they work like a dream.

Oh the DKG brace also help a lot,,but I end up making a Much bigger one out of compaose the other day to increase tyre clearance,,
i show you guys later.

 

[patineto]

The laws of physics dictate that you would fold the front fork first.
Tooth loss would undoubtedly ensue.

Dude you read my mind,,the Instigator fork looks very strong compare to the original fork, but side by side with the FUNN 20MM fork looks paper thin,,

more than fork i was worry about the QR and the drop outs failing,,so the 20MM axle hopefully will do the trick.

I'm getting the brake bosse(in the back like the old Pace forks) weld at this moment and hopefully i will have it install by next week..

 

[patineto]

You guys know far more about current product(I'm totally old school) so if you have any suggestions on better products or design please let me know

 

[patineto]

A shop near me has a 10" rotor made for a tandem. Magura I think. I have also sen tandems with drum brakes mounted to friction shifters as a sort of down hill cruise control.

Cool setup though.

I think Hope offer a "Custom" rotor service, in fact my friend sandro at galfer can make me anything i want (for a $$$$$...price) actually any lazer cutter shop can cut a stainless like is nothing but maybe what you want is something like this

just Kidding that 320MM single rotor stop my KTM 950 in a hurry and for sure will bend a bicycle fork in no time

 

[patineto]

here is my last developments
Finally I got all the components to finish my 20MM fork project

*The fork is a "FUNN" 20MM with brake post welded in the back of the fork to run V-brakes.

*the Hub is a 36 hole Big-Um with a 20MM axle.

*Headset King steel head with a 20Mm insertion.

*the rim a Atomlab Trailpimp no eyelets but i install brass washers at the nipples to reduce friction.

*The spokes,,,triple butted DT spokes (Alpine i think is their name) with aluminum nipples (No never have failures on the many wheels I build with them) lace 4 cross.

*the tyre a Michelin 2.something' but i can fit 3,0" if i ever want to.

*the V-brakes are old style XT calipers (so far I can not find anymore XTR's for cheap) no fork brace so far but not as necesary as if you running the brakes forward (convensional way)

*The disc brake is a HOpe Enduro with a C-2 type lever running on a close sistem with a 205MM Hope rotor (5 Bolt rotor).

anyway here are the first pictures of the new fork and wheel,, the bike feels amazing, no fork flex and for sure no Quick release failures or fears but still resilient and some how cushion (maybe the lace pattern and the big tyre)
the only and very ovius problem so far is that the standover height was reduce drastically (about 3 inches from the stock fork) in fact with my almost 34' legs i'm touching the toptube when I stand on the ground for my good luck i'm kind of use to it do to my motorcycle riding.

anyway enjoy,,,If you like a diferent kind of Monster Bikes that is..

notice the second "stem" to mount the light (got the idea from a link on a english forum..)

the ground clearance is impresive but i still mount the bash guards just in case, not to mension they help to protect your pants if you go on a leasure ride.

i still need to finish the rear Disc brake caliper mount and then the project will be kind of "Complete",,well until some other crazy idea comes around..

the rear hub is also a Hope Big-Um and so far is being trouble free even if is being subjected to incredibly step high climps, will see when it fails.

well i hope you guys and gals like it, is for sure not a Freeride bike but at the same time is extremlly challenging and also a ton of fun do to the skill require to perform even the smallest task like for example lifting a wheel anyway is diferent and for sure i like it..

to me RIGID is the way to go, at least for a hardtail since the fork will move up and down like one of those "old canaries that drink water from a glass"..

the next project is to develope and install a independing pedaling sistem similar to the "Da vinci" conceptso each person can pedal at their own cadence but the sistem will be able to be "LocK" for In- face cranks when the singletrack apears


and on the next stage I will love to figure out a way to mount a G-boxx sistem so the desastrous shifting problems related to tandems will be a thing of the pass, but sadlly that still a long way away from my reach at the moment.

well a man can dream or not...!?!?

 

[sanjuro]

1. Why don't you explore using a motorcycle front hub? I don't know much about it, but I think they are 20mm as well, and you could mount a rotor on each side. Obviously you will need to have a fork made or altered, but it would easier than making a dual sided hub.

2. Have you thought about Magura Rim Crushers? The only hydraulic rim brake that I know of...

 

[splat]

Sweet!!!

I am currently in the process of converting my Tandems rear Drum Brake to a Disk brake. want more power.

I think this should be you next project

also I have an old Bomber in my garage I got from stosh to give to MMcg and it has Disc tabs on both sides ofthe fork

 

[patineto]

1. Why don't you explore using a motorcycle front hub? I don't know much about it, but I think they are 20mm as well, and you could mount a rotor on each side. Obviously you will need to have a fork made or altered, but it would easier than making a dual sided hub.

So far i don't think i need more brakes, actually last night i did my first "Stoppie" with a passanger on the bike, was not to high(about a foot) plus she is really light (about 115) for sure all the brakes i will need.

also motorcycle hubs come in many sixes,,the ones on my KTM 950 are about 32MM I.D. but even the ones on a really small bike still far to big and more than anything heavy (more rotating mass) plus most of them are design for single brake rotors, so the exercice is kind of pointless...

actually even the best perfectlly set up caliper sistems are soppose to waste in drag at least 1 horse power on a motorcycle do to just friction,(not to mension rotating mass and giroscopic forces) that will make the exercice efford futile since a well prepare Human being produce about half of a horse power at steady effort and about 1.1 HPs for a few seconds burst

2. Have you thought about Magura Rim Crushers? The only hydraulic rim brake that I know of...

like the magura H-33..?
actually i was trying to stay away from Hydrolic sistems, basically I was looking for two diferent sistems that can work at Unison (at the same time) or indepent from each other not to mension have a back-up ....A.K.A. limp mode if something go really wrong with one of the sistems

 

[splat]

here is my set up , I use it mainly on the road with my son here is the one time we tried it off road.

note the conversion crank my son is using
with him on the back stopping power really is not a big issue right now, but as he get bigger and stronger it will be

here is the whole story of that
http://www.nemba.org/yabbse/index.php?board=34;action=display;threadid=388

 

[patineto]

Sweet!!!

I am currently in the process of converting my Tandems rear Drum Brake to a Disk brake. want more power.

whatever you do keep the rim brakes too..for sure the brake s will be stronger, but sometimes disc brake soffer from heat fade and even warpage (I'm sure you guys know this better than me) when the drum brakes are made to be engage for a long time and dissipate the heat ussing basic thermodinamic laws a.k.a. expose surface area.

I think this should be you next project

Dude i already have suffient trouble convincing my friend to go for a ride on this thing,,I think they know me better than I think they do..

so a triple is out of the question,,plus the flex to much and they are even more dificult to ride on tight single tracks,,no way jose.

also I have an old Bomber in my garage I got from stosh to give to MMcg and it has Disc tabs on both sides ofthe fork

I also have two of them, i just never saw a caliper that can work on the right hand side of the forks...

actually i don't think you need two disc brakes,,I'm being looking into some of the old Sper-t's 1999 i think that have Canti mounts and also disc mounts, that will be a good setup if i ever want to go into a Bouncy bouncy fork, since a single crown fork will be a warranty trip to the dentist if you get my drift...

 

[patineto]

here is my set up , I use it mainly on the road with my son here is the one time we tried it off road.

note the conversion crank my son is using
with him on the back stopping power really is not a big issue right now, but as he get bigger and stronger it will be

here is the whole story of that
http://www.nemba.org/yabbse/index.php?board=34;action=display;threadid=388

Good for you..
sometimes I just want to have a son or even better a dauther so i can teach him(her) all this things...
well first I need to find the wife, well at least the tandem is a good "Chick magnet" that a start.. :dancing: