|advice on rim/tire etc. for riding the brakes a lot?||DougSloan|
Jan 8, 2004 10:28 AM
|Goofy question, I know...
Let's assume the bike is a fixed gear and will be descending 10-15% slopes that go on for 15 miles, riding the brakes to keep the speed to about 25 mph where you'd otherwise be coasting at 55-60+ mph. Assume also that disc brakes are not an option, and you must use aluminum box section rims, minimum 32 spokes, with an 18 pound bike and 155 pound rider.
What rim/tube/tire/strip/brakes would you use? Obviously, there's going to be a lot of heat and increasing pressures in the tires. Brake pads could even be subject to melting. Tubes might melt. Tires could blow from overpressurization. Rim strips could melt the adhesive and move. Tubular glue issues almost make them impossible.
Good application for Tufo tubular/clinchers? (I otherwise don't care for them.)
Does anyone make finned brake pad holders?
Keep in mind that the same setup must be ridden up the hills, too, in the same gearing.
Any ideas? Thanks.
|Wow...that's a tough one....||Gregory Taylor|
Jan 8, 2004 10:40 AM
|I can't think of tire/rim/brake combo that would survive that kind of abuse.
The easiest thing might be a flip/flop hub set up with a freewheel on one side. Do the climb fixed, stop, flip the wheel to the freewheel side, and descend at normal speeds. Wouldn't take but a minute to do, and Tour riders up through the late 1930's did just that trick.
I read an account of a gentleman who rode from California to New York (via the Dakotas) on a fixie back in the late 1890's. He had a similar problem -- controlling speed on long steep descents with no brakes. He tacked that problem by getting a rope and dragging a huge log behind him on hills.
Jan 8, 2004 10:46 AM
|Rules will allow only one gear the whole way (FC508), and even with a flip/flop, you can only get so much range due to chain and dropout lengths.
I thought about a parachute-type jacket of some sorts. A good cross wind could be a problem, though.
Pretty much need to figure out how to make the brakes work.
Are there any tubular glues that can withstand high temps?
|has the animal returned, with a canine sickness?||JS Haiku Shop|
Jan 8, 2004 10:58 AM
|you aren't really considering riding the fc508 fixed, solo, are you, Do(u)g?|
|sniffing the wind at this point, but I over plan, as you know nm||DougSloan|
Jan 8, 2004 11:00 AM
|sounds rabid to me. nm||JS Haiku Shop|
Jan 8, 2004 11:32 AM
|wouldn't be fun if it weren't||DougSloan|
Jan 8, 2004 11:39 AM
|I don't see much fun in doing the same thing, but just trying to go faster or even equal a prior time. To me, there's a lot more fun in doing something new, different, and challenging. This idea presents a whole new dimension, or maybe fewer dimensions, to the event. Just get on a bike and ride. It still takes plenty of planning ahead of time, but during the event you just pedal and brake. That's it.
The real trick is to find the right gear that allows you to climb the hills, and they are whoppers there, and do so without destroying your knees before half way, but at the same time still allow descending and even flat ground riding as quickly and painlessly as possible. My thinking is to gear for the steepest climbs, and just ride the brakes on the descents and spin your butt off on the flats.
Now, if I do this, I'm prepared to bump up against the 48 hour time limit, almost 12 hours slower than last time. Just finishing would be good enough for me.
And yes, I'm overdosing on the glucosamine/chondroitin.
|The answer I have found.....||CARBON110|
Jan 8, 2004 11:00 AM
|Having ridden those conditions on the parkway where you can descend for 15 + miles as fast as you can peddle as well as VT where the grades are 18+% for 3-4 miles my best bet for non-racing are open pros with non-warn brake pads. For tubulars Tufu or Conti glue works AS LONG as you apply 3 layers of glue. Its the only way my team rides tubies in 90+ degree heat with serous decents like the Roan Groan race. Apply one coat to rim and tire and let sit for 15-20 minutes. Apply second and so on. Getting a flat changed will be hard so you should anticipate that.
Open pros have HUGE brake surfaces and have never let me down even when my buddys where taking me on 9+mile descents when I first started riding..you remember those days, riding the brake was like a given since you were staring at your computer and how damn fast 30-40mph felt back then LOL! Now I can answer my cell phone goin 35 HAH ! Anything over that the other person can't hear a damn thing I'm saying LOL
|Does the "One Gear" rule...||Gregory Taylor|
Jan 8, 2004 11:03 AM
|...allow you to use the same number of teeth on the fixed and the freehub side? If so, that would solve your chain/dropout problem, and even if you spin out the freehub gear, you would still pick up time coasting versus riding the brakes to keep the rpm's down.
Or am I all wet?
Jan 8, 2004 11:12 AM
|...you could keep it fixed, use a Connex link and remove the chain for the downhill. Might be a hassle...but it is simple and relatively quick.
I like the disk brake on a chainring concept. An Avid mechanical disk brake caliper mated up to a simple bracket on the bottom bracket. Hmmmmmm.....
|I like this: remove the chain. Or, lift your feet up! nm||Spunout|
Jan 8, 2004 11:19 AM
|rules and spirit of the rules||DougSloan|
Jan 8, 2004 11:28 AM
|The rules/idea here is to remain in the same gear, feet on the pedals, in fully functioning fixed gear mode the entire distance. Also, the idea is to use traditional "Eddy Merckx" (hour record) type equipment, albeit with brakes and other essential safety equipment. That's why I'm focusing upon just getting the brakes to work well. Will all the diverse intelligent minds here, I want to exploit all that brain power and experience to ensure there's not something I'm missing.
All that aside, the *real* issue is getting UP the hills.
|While Henri Desgrange thought that derailleurs were for wimps...||Gregory Taylor|
Jan 8, 2004 11:49 AM
|...even he allowed his riders to coast down mountains.
This race sounds pretty sick.
|left field...||Arnold Zefal|
Jan 8, 2004 10:57 AM
|know a good machinist? maybe a small disc setup on the inside of the chainring. maybe start with a triple crankarm and mount the rotor to the granny ring mounts. caliper could clamp on down tube. you could cable activate with a knob that could be set as a governor. leaving your hand free to modulate the brakes if you needed more slowing, and leaving you a free hand to squirt your water bottle at the disc set-up if it overheats.|
|wow, now that's thinking; will consider nm||DougSloan|
Jan 8, 2004 11:01 AM
|wow, now that's thinking; will consider nm||JBergland|
Jan 8, 2004 11:56 AM
|Might need a couple different 'types' of brakes in place???? With the heat build-up and wear-n-tear, a person might be best off with a couple different options to choose from.
Jan 8, 2004 11:56 AM
|I like that idea, but just as a thought. You could take another crankset and mount in on the left side and turn that into your disc break. Basically the same idea, but this way might free up some space. Or you could use both. Of course you've have to get an extra right pedal or rethread the crank.|
Jan 8, 2004 12:06 PM
|I'd want to think that one through a bit. You'd be using your crank to brake your rear tire via the chain, and I'm not so sure the chain is designed to withstand those types of braking forces.|
|not an ideal situation...||Arnold Zefal|
Jan 8, 2004 2:05 PM
|but the whole idea of this ride is pushing things so....anyway I think a top quality 1/8 Kerin track chain would be up to the task, especially if you swapped it out after the big descents. it would only take a minute with a few pre cut chains on hand. if you think about it constant steady back presure may not be anymore load than driving forces in foward motion (?). that's why I say to design the system to lock on, and not just be jerky on and off motions on the drivetrain. be a cool experiment at least.|
|not an ideal situation...||JBergland|
Jan 9, 2004 7:37 AM
|Early (mid 80s) Polaris ATVs used a similar braking system for the rear end of their machines. The disc was connected to the driveshaft/engine and used the chain to brake the rear axel. The design worked ok, but wore out chains very fast!! A traditional disc-on-the-rear-axel was developed after only a couple years.
Something else to consider, if the chain breaks, you'll have no brakes (at least on the rear)!! Even with something as strong as a track or BMX chain, the chances of snapping a chain given the conditions that have been described is considerable.
|re: advice on rim/tire etc. for riding the brakes a lot?||irregardless|
Jan 8, 2004 11:46 AM
|I regularly do repeats on a one mile 12% hill. You're kind of stuck between a rock and a hard place. Don't brake that much, go fast, and if you blowout anyway because of the heat in your tires, you're looking at a nasty fall. Brake a lot, go slower, higher risk of blowing out from heat buildup, but you're less likely to be seriously injured because of the slower speed. For me, the tires don't seem to make as much difference as the tubes. Don't try any of the lightweight tubes (the 70 grammers), they blow out quickly and take the whole tire off the rim, and it's not a pleasant experience to blow out on that steep of a grade. Once I went to thicker tubes, no more problems. I use open corsas and regular thickness tubes of any of the standard brands. For the length of your decline, I'd get the thickest tubes possible.|
|good points, eerieguardless nm||DougSloan|
Jan 8, 2004 11:53 AM
|The only thing I can think of...................||Len J|
Jan 8, 2004 12:16 PM
|is Open Pros, which dissipate heat well, coupled with oversized canti brakes/brake pads for the same purpose.
It sounds like success in this race will depend as much on your aerobic fitness and ability to spin at high rates for extended periods of time as your ability to climb. Makes for some interesting thoughts on training.
I would also pose this question to Sheldon Brown and see what he suggests.
|re: advice on rim/tire etc. for riding the brakes a lot?||witcomb|
Jan 8, 2004 12:37 PM
|I saw these pads just the other day. I have no idea how they perform, but I would imagine they would hold up much better than standard pads, I'm sure melting wouldn't be a problem.
On another thought, how hard would it be to try a drum brake setup? I've never seen these but then again there is lots I've never seen. Could a hub be built with a drum brake around it? This would keep heat away from your rim and you wouldn't need any special mounting on your frame.
|well, they do exists||witcomb|
Jan 8, 2004 12:51 PM
|Well, they do exist as I would have expected. This might help out on the front. The combination drum and rim brake should be a lot of force. Finding a similar drum for the rear could be hard, I have no idea.
|Highway pegs brazed on the fork? Coaster brake? nm||dzrider|
Jan 8, 2004 1:00 PM
|Sorry, hadn't read about keeping your feet on the pedals.||dzrider|
Jan 8, 2004 1:17 PM
|There's a one armed crit racer here in New England who as a gadget that puts both brakes on one lever. With two of those, you could set the bike up with both cantis and conventional road brakes. The road brakes would have to be placed behind the head tube and in front of the seat stays, but that doesn't sound too hard.
Could a freewheel be modified to work on the crankset? I had a 1971 Saab 96 that worked kind of like that.
|An answer perhaps goofier than the question||JFR|
Jan 8, 2004 1:01 PM
|But what about a second rim brake. Either on the opposite side of the brake bridge, or at the chainstay yolk? The cable could be somehow attached/welded to the existing cable so the lever would actuate both brakes.
I think this system would run cooler... more powerful for sure.
|why are disc brakes not an option?||gtx|
Jan 8, 2004 1:54 PM
|you can get discs to work on a fixie or ss.|
|might be for rear||DougSloan|
Jan 8, 2004 2:17 PM
|After this discussion I'm thinking more about that, particularly on the rear, where for flex issues would not be as great. I'll running it by the "rules" guy. Thanks.
|might be for rear||gtx|
Jan 8, 2004 2:49 PM
|yeah, you can go with an eccentric bb or with something like this Paul Components setup|
|that's pretty cool nm||DougSloan|
Jan 8, 2004 3:02 PM
|Morati SC 1.3 Ti Pro disc brake road bike||irregardless|
Jan 8, 2004 2:26 PM
|might be the way to go||DougSloan|
Jan 8, 2004 2:39 PM
|Must be steel frame, but I see that Vanilla makes a steel bike with a rear disc mount, but not horizontal rear dropouts:
They make fixed gear hubs with disc mounts?
|Don't know if that would work...||Gregory Taylor|
Jan 8, 2004 2:49 PM
|The position of the disk relative to the caliper would change with your gearing...a horizontal dropout wouldn't work.|
|what's wrong with the front brake?||cyclopathic|
Jan 8, 2004 2:59 PM
|cheap 55$ xross steel fork will work any frame, and Avid road disk is 100$|
|that looks like a deal, and might be ideal, actually; thnx nm||DougSloan|
Jan 8, 2004 3:17 PM
|what about the horror stories of..||colker1|
Jan 8, 2004 7:45 PM
|vertical forces applied from disks pushing the front wheel away from the droop outs? on a highly stressed enduro event like the one doug is talking about...|
|that's certainly something to watch; thanks nm||DougSloan|
Jan 9, 2004 7:45 AM
|thats why the fork has lawyer tabs... NM||gspot|
Jan 9, 2004 4:52 PM
Jan 8, 2004 5:17 PM
|The Surly Karate Monkey comes with horizontal dropouts and a disk brake. So it is possible. Maybe not ideal, but possible.
|I'd try heavy duty tandem rims||cyclopathic|
Jan 8, 2004 2:31 PM
|like T-520, dryad, Rynos or CR-18. Check with tandem maillists they might be able to suggest something. But honestly, I'd get the cross fork with disk tabs and use mechanical disk like Avid or Hayes, you only need front. Avid makes road specific disc with reduced pull ratio.
PS Bikeman sells cheap 55$ and reasonably light (625g) steel cross fork with tabs, here's your URL http://www.bikeman.com/miva/merchant.mv?Screen=PROD&Store_Code=BOS&Product_Code=FK1268&Category_Code=COMPFKCROSS
|Here's what I am thinking...||SenorPedro|
Jan 8, 2004 3:53 PM
|Definitely use a good quality clincher rim, preferably one dedicated to touring.
I like the idea of the disc brake on the front, will provide a good deal of trouble-free stopping power without the heat/rim issues. If you can find a 36 holer, then go with that to help combat all the extra torque on the spokes.
I would suggest doubling up on the front at least, by using the disc hub and then canti brakes on the front and the rear. These should provide stronger stopping power than road calipers without too much weight penalty.
The way to operate your double front setup could be one of several options, all derived form the tandem world. Tektro makes a set of aero levers that have two cable spots in them, allowing the use of a rim and drum brake simultaneously - a disc in this case.
Other options include using a barcon to modulate your disc brake in a drag-brake fashion, i.e. set it and leave it on. These can also be mounted with Kelly take offs for a different position.
All in all, if discs are allowed, go that route by all means. Otherwise I like the coaster pegs idea.
Be sure to give us a pic of this monster when it is done.
Jan 9, 2004 8:32 AM
|Seriously, though, it seems like a heavier rim would be able to hold more heat energy, and if it were in the form of a deep-V, would have more surface area to dissipate that heat.
I'm pretty sure aluminum alloys have fairly good heat conduction, so heat dissipating from the brake tracks to the rest of the rim should be fairly quick. Obviously, there's a weight penalty, but there would be with a wider box-section touring rim, and the v-shape rims should be good and strong, too.
As far as brake pads, the Zipp carbon type are more for carbon rims, which don't absorb heat as readily as metal rims. This leads to heat being held in the pad, which makes them more likely to melt. They're a fine idea, but finding some finned pads, and they're still out there, might be more economical.
Also, with a fixed gear, couldn't you be applying back pressure? Obviously, it's different for descents that long, but couldn't you still use both brakes alternately, and be applying backpressure when the front is engaged? That's the standard technique to avoid overheating the rims with a regular geared bike, and seems to work. Disks would also work, but disks on a fixed gear gets complex, though an eccentric BB makes this easier.
|how do you apply back pressure on a gearie bike?? NM||gspot|
Jan 9, 2004 4:55 PM