|   DH frame design | crazbiker4
Jan 21, 2004 6:05 PM | | Why have none of the companies that make DH frames design a frame like a dirt bike frame? I mean a frame that is scaled down for a 26in bike and that is made out of alum. Dirt bikes have a very smooth linkage setup and would allow downhillers to have more travel.
If you cut of where the engine goes and take the subframe off to put a place for a seat, and slim the frame down to fit a 26in bike. As rear brakes go, a system like ones on dirt bike could be designed. look at the link to understande more!
http://powersports.honda.com/the_story/insidehonda/?TargetUrl=Inside/Inside_Honda_0063.asp&ArticleCategory=Behind+the+Machine&Year=2001&PrevPageTitle=Article+List |
| the future is here!!! | zedro
Jan 21, 2004 8:34 PM | | there are bikes that have the similarities as far as suspension and braking goes. But alot of the DH designs are based on the premise that humans arent like motors and our transmissions arent like dirtbikes.
Using such a sub-frame design would be extreme overkill and pretty hard to pedal. Theres reasosn why DH bikes are the way they are. |
| the future is (not) here!!! | crazbiker4
Jan 21, 2004 11:07 PM | | If you read what I wrote then you would not have made a coment about the sub frame because i said to take it off and make a seating area and as for braking there is not mtb system that is even close to a dirt bikes. Look up some info on dirt bikes to understand what i am saying. If you read MTB action mag. then you would know that honda has a mtb with a gear box like a dirt bikes! Read Up!!! |
| the future is (not) here!!! | cguzz
Jan 21, 2004 11:51 PM | | Can't argue with MTBR LOL!!!! |
| can't argue with MBA | cguzz
Jan 21, 2004 11:54 PM | | |
| ya i'm fully aware of Hondas DH bike... | zedro
Jan 22, 2004 12:24 AM | | i also know its a concept bike that cost 70 000$ and is not indended to ever be produced.
As far as transmisson bikes go, its nothing new either. GT had a prototype, Nicolai has various offerings, BCD did one (although it was a Shimano geartrain mounted into the frame, which is what the 2nd Honda bike is rumored to be), i'm pretty sure theres others out there. The big limitation is cost and weight right now, otherwise you would see tranny bikes everywhere (its not that no ones thought of it, its mearly a prohibitive technology). But regardless weither it has a transmission, the difference between a long stroke low RPM human and short stroke high RPM engine will change how the basic suspension and drivetrain is layed out.
As for brakes, i dont see anything special there, just a simple solid mount to the swingarm, with a single or dual piston setup. What am i missing there? |
| just to add... | zedro
Jan 22, 2004 12:36 AM | | since i keep unwittingly snubbing Dave Weagles (from Evil Bikes)efforts, he in conjunction with Nicolai bikes are developping a frame and gearbox interface standard called the G-Boxx, which is still a couple of years off from maturing. Read up would ya! :b |
| evil gearbox | _rich_
Jan 22, 2004 5:13 AM | | here is what it looks like if anyone wants to check it out..
http://www.evilbikes.com/2013i_gboxx/2013i.htm |
| Zedro, and maybe a Rotec? | TNC
Jan 22, 2004 4:40 AM | | This bike struck me as being very "moto" in some aspects of its rear design--swingarm, linkage, long wheelbase. But despite that, it seems to be less efficient without producing the level of performance offered my many other DH bikes available. As a long time motorhead myself, I agree with you that the 30-60 hp engine in the chassis makes a ton of difference in several critical areas of frame design priority, along with the requirement to handle around 12 inches of suspension travel and 225-250 lbs. (without a 175 lb. rider) that can be slammed to the ground from the heights, distances, and speed that they can attain. Just think about the forces dealt with by a moto rear suspension when the rider launches from a dead stop or walking pace to full throttle when the clutch is released in some nice traction-rich soil. I'm certainly no engineer on this topic, but it does seem like an apples and oranges issue in many critical design areas. I'd say the front fork dynamics between motos and bikes is the most common area of crossover that the two have. Looking back at old moto rear suspension design in the 70s, like the Yamaha monoshock, you see more similarity with some of today's bicycles--single pivot, single shock--at least it sure looks similar. Obviously moto designs have moved on substantially from back then. |
| the honda DH bike is very much NOT like dirt bikes | Jm.
Jan 22, 2004 10:01 AM | | because the suspension system is a monopivot, whereas 95% of dirt bikes use moto-link systems. |
| re: DH frame design | Sparc
Jan 22, 2004 7:17 AM | | You're really all missing the point - there's no debate!..MTB Action said so, thus.. it MUST be true!.. |
| Mountain Cycles = Honda minus motor | henryl
Jan 22, 2004 8:11 AM | | I guess I am not seeing your point. The Mountain Cycles Shockwave and Sin both are basically the same as the Honda in the link you supplied. Already being done. Single pivot, motorcycle linkage at shock, disc brakes, monocoque body, etc. |
| re: DH frame design | James : Go-Ride
Jan 22, 2004 8:52 AM | | There are a lot of bikes that take many hints from moto bikes. Most noticeably are the Rotec (both past and present) and the Tomac 204. The old Rotec frames had the exact same linkage as a Honda CR125, just scaled down for 8 inches of travel. The new Rotecs, as well as the entire Foes line of DH bikes for the last several years, are almost identical to a KTM SX no-link setup. Tomac 204s have an identical linkage to a KX125, but scaled down.
James
GR.c |
| Cheeta Proline, Rotec, Giant DH, Tomac, etc | Jm.
Jan 22, 2004 9:54 AM | | same linkage arrangement as a dirtbike. |
| Thanks!! | crazbiker4
Jan 22, 2004 10:19 AM | | Thanks for showing me that there is frames that are like dirt bike frames. I will look for them when I buy a DH bike. |
| not to mention the Brooklyn Machine Works RaceLink. nm | mosplat
Jan 22, 2004 11:09 AM | | |
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