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This is a discussion on Building Custom Seat Question within the Technical forums, part of the Caferacer.net Forums category; Originally Posted by Cyorg Not sure who “you guys” are and not sure how you know it’s a DR650 frame unless my reading comprehension has ...

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  1. #21
    Senior Member irk_miller's Avatar
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    Quote Originally Posted by Cyorg View Post
    Not sure who “you guys” are and not sure how you know it’s a DR650 frame unless my reading comprehension has gotten worse, which is a possibility or he mentioned it on another thread. Don’t most dirt bikes have all kinds of interesting flex built in? You tell me, I don’t really have any desire to read up on them. Let’s assume yes. Combine that with a (presumably) first attempt to make major modifications to a frame. USD forks, a swingarm that isn’t likely go to flex behind that engine, fat tires etc etc. and my guess would be that for a street bike... or whatever he uses it for, it will flex more and not in a desirable way.

    OP, did you plot out the rake and trail before you started.? If not, you may be in for a surprise. Even if you did plot it out, the change in ride height will have changed that. You may want to make further changes or swap out the triple, to get more trail. Might want to add a steering damper, but better to have them set up so they don’t shake to start with.
    LOL. You're too lazy to read through the entire thread for context, and you criticize the OP's decisions and my comments. Funny. Anyway, the DR650 is just one example. That is in reference to the comment that a dirt bike frame can't handle the power of a GS500 engine. I just pointed to one example of a dirt bike with similar power. I gave a specific response to a general and inaccurate statement. The other comment was that dirt bikes don't have to lean a lot and a reference was made to arena cross. Okay. Because so many people in the world do arena cross. Dirt bikes lean. A lot. If you actually ride them. As far as flex, anything made from chromoly steel has flex, because chromoly steel has flex. Chopper frames have flex and it's a good thing. The flex keeps them from cracking. Aluminum doesn't like to flex. It cracks. But steel, steel can flex. I raced mountain bikes for many years and it took me a long time to buy into aluminum frames (I quit doing it before carbon fiber became so big).
    I preferred chromoly because it flexes. Aluminum framed bikes with no suspension shattered your teeth and I didn't want to have suspension to counter the stiffness of the aluminum frame. Also, I'm pretty sure feather bed frames have a wee bit of flex in them. Funny how so many people love feather bed frames, since they suck so bad and are inherently going to kill you because they have flex. I might be wrong about feather bed frames, but it doesn't matter. Basically, you guys are wrong that a dirt bike frame can't be a good base for a bike with excellent road manners. I showed you an example of a supermoto DR650. It has good road manners. In the pic it is leaning. A lot. I built a similar bike from an F650 frame and power plant. It's amazing in the mountains of Western North Carolina. Not really a dirt bike, the stock F650, but look at their frames. If you want to show up with your amazing sport bike and race me in the mountains on my F650, I'll be happy to ride. I'll even do it with my Karoo tires. See if you can lose me, or even keep up. The OP's bike may have issues, but it won't be because dirt bikes can't be made into great street bikes.
    Last edited by irk_miller; 04-23-2019 at 07:35 PM.

  2. #22
    Senior Member woodsman's Avatar
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    Quote Originally Posted by irk_miller View Post
    LOL. You're too lazy to read through the entire thread for context, and you criticize the OP's decisions and my comments. Funny. Anyway, the DR650 is just one example. That is in reference to the comment that a dirt bike frame can't handle the power of a GS500 engine. I just pointed to one example of a dirt bike with similar power. I gave a specific response to a general and inaccurate statement. The other comment was that dirt bikes don't have to lean a lot and a reference was made to arena cross. Okay. Because so many people in the world do arena cross. Dirt bikes lean. A lot. If you actually ride them. As far as flex, anything made from chromoly steel has flex, because chromoly steel has flex. Chopper frames have flex and it's a good thing. The flex keeps them from cracking. Aluminum doesn't like to flex. It cracks. But steel, steel can flex. I raced mountain bikes for many years and it took me a long time to buy into aluminum frames (I quit doing it before carbon fiber became so big).
    I preferred chromoly because it flexes. Aluminum framed bikes with no suspension shattered your teeth and I didn't want to have suspension to counter the stiffness of the aluminum frame. Also, I'm pretty sure feather bed frames have a wee bit of flex in them. Funny how so many people love feather bed frames, since they suck so bad and are inherently going to kill you because they have flex. I might be wrong about feather bed frames, but it doesn't matter. Basically, you guys are wrong that a dirt bike frame can't be a good base for a bike with excellent road manners. I showed you an example of a supermoto DR650. It has good road manners. In the pic it is leaning. A lot. I built a similar bike from an F650 frame and power plant. It's amazing in the mountains of Western North Carolina. Not really a dirt bike, the stock F650, but look at their frames. If you want to show up with your amazing sport bike and race me in the mountains on my F650, I'll be happy to ride. I'll even do it with my Karoo tires. See if you can lose me, or even keep up. The OP's bike may have issues, but it won't be because dirt bikes can't be made into great street bikes.
    I don't know who you guys are but this guy read what Geeto and Cyorg wrote and I don't see where anyone said the frame wouldn't handle the engine. I agree a dirt bike can be converted to run on the track, I used to do it. It can even be chopped and a different swing arm added, if you want to do something that stupid..to prove it can be done. Some dipshits do stuff like that. This one is poorly done and will behave badly because of the flex allowed by the weakness in the tie in between the frame and the swing arm. That is the flex I'm referring too.

    Your "come race me challenge" is childish.

  3. #23
    Senior Member Cyorg's Avatar
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    Quote Originally Posted by irk_miller View Post
    LOL. You're too lazy to read through the entire thread for context, and you criticize the OP's decisions and my comments. Funny. Anyway, the DR650 is just one example. That is in reference to the comment that a dirt bike frame can't handle the power of a GS500 engine. I just pointed to one example of a dirt bike with similar power. I gave a specific response to a general and inaccurate statement. The other comment was that dirt bikes don't have to lean a lot and a reference was made to arena cross. Okay. Because so many people in the world do arena cross. Dirt bikes lean. A lot. If you actually ride them. As far as flex, anything made from chromoly steel has flex, because chromoly steel has flex. Chopper frames have flex and it's a good thing. The flex keeps them from cracking. Aluminum doesn't like to flex. It cracks. But steel, steel can flex. I raced mountain bikes for many years and it took me a long time to buy into aluminum frames (I quit doing it before carbon fiber became so big).
    I preferred chromoly because it flexes. Aluminum framed bikes with no suspension shattered your teeth and I didn't want to have suspension to counter the stiffness of the aluminum frame. Also, I'm pretty sure feather bed frames have a wee bit of flex in them. Funny how so many people love feather bed frames, since they suck so bad and are inherently going to kill you because they have flex. I might be wrong about feather bed frames, but it doesn't matter. Basically, you guys are wrong that a dirt bike frame can't be a good base for a bike with excellent road manners. I showed you an example of a supermoto DR650. It has good road manners. In the pic it is leaning. A lot. I built a similar bike from an F650 frame and power plant. It's amazing in the mountains of Western North Carolina. Not really a dirt bike, the stock F650, but look at their frames. If you want to show up with your amazing sport bike and race me in the mountains on my F650, I'll be happy to ride. I'll even do it with my Karoo tires. See if you can lose me, or even keep up. The OP's bike may have issues, but it won't be because dirt bikes can't be made into great street bikes.
    I’m not the guy who mentioned the leaning, you’ll have to take that up with him. Not sure where I said you couldn’t make a decent street bike from something originally designed for off road. Seen a few I’d love to own. I think my point was... if it flexed with the original engine, which it likely did (and was supposed to) and my assumption yes it was an assumption that his new engine has more power than what was in there, so depending on how he rides it... plus the changes he is making are going to make it flex in a bad way. As for your invite, I have to confess that bench racing has never my cup of tea.

    Yes I’m criticizing some of his work. Should I be giving him a hand job? I’m not going to post my resume, and although I still have lots to learn (my favourite thing btw), I didn’t just fall off the back of a turnip truck. I am fortunate to know a couple of folks who build frames and are not only extremely good at it, they are great at sharing their knowledge. When I do things where I’m pushing my limits, I ask them for feedback or criticism if you like. As in both barrels don’t hold back. Learn a lot that way. Anyhooo this is all pretty redundant. When these things show up should we just swoon over the thing and send him on his merry way or try to help prevent some pain. He’s been pretty straight up, so think he’s worthy of some help. If he doesn’t like my delivery, he can tell me to fuck off and I’ll stay out of his thread.
    Last edited by Cyorg; 04-23-2019 at 08:36 PM.
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  5. #24
    Senior Member Geeto67's Avatar
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    Quote Originally Posted by irk_miller View Post
    You guys need to read up a little more about dirt bikes. A GS500 and a DR650 produce virtually the same horsepower and the DR is geared for more torque. If you guys don't think dirt bikes, or even more so, dual sports don't do much leaning than please let me never get behind you on trails or twisties. Dirt bikes lean, especially in supermoto gear, you're just in a different riding position.
    I think the speeds are different for super moto than for AMA superbike, MotoGP, and even club road racing.

    Not saying dirt bikes can't be made to handle, they can, but it takes some effort that I am not seeing here. I feel like the DR650 is a bad example because in the last 10-15 years suzuki really beefed up the headstock, front down tubes, and swingarm pivot of that frame in an effort to tame some wiggle that supermoto guys were seeing in racing.


    The reason I bring up leaning in competition is...well...your swingarm is a lever, and leaned over it sometimes acts like a lever that tries to twist the chassis. It's not about horsepower, the swingarm doesn't know it's on a 200hp superbike or a 50 hp vintage racer, it does know that at 70mph gravity, centrifugal force, friction, etc are all acting on it the same. A lot of people assume that hih hp sportbikes have robust swingarm pivots because they are high hp and the engine torque is somehow gonna twist the chassis, but the crank throws on most motorcycle engines are 90 degrees to the chassis so that's not the issue - a high hp superbike is capable of faster speeds and the robust swingarm pivot area is there to keep the swingarm from throwing the frame out of square when you try to lean the thing over at 100+ mph and expect it to dig in and carry you through the turn.

    Nobody is expecting a DR650 to carry sport bike speeds on a road course. I've watched the supermoto classes at mid-ohio, a lot of those bikes look pretty shaky coming out of the road course turns. Yes they manage to get through it, but not at the same race pace as a comparable hp road racer.
    Last edited by Geeto67; 04-24-2019 at 07:15 AM.
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  6. #25
    Senior Member TrialsRider's Avatar
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    Quote Originally Posted by woodsman View Post
    ... Your "come race me challenge" is childish.
    and yet very enticing.

  7. #26
    Senior Member woodsman's Avatar
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    Quote Originally Posted by TrialsRider View Post
    and yet very enticing.
    I've a lifetime of being told by citiots they were going to show me how to ride the woods.

  8. #27
    Senior Member irk_miller's Avatar
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    Childish? How in the hell did racing begin in the first place? This site has a message function. Let's race. I like racing. Been doing it since I was eleven and it's fun. I mean, everything we build is supposed to function like a race bike, and supposedly you guys are the best at building race bikes.

    Anyway, for years the second fastest lap record on Mid-Ohio was done on a Supermoto... against super bikes.

  9. #28
    Senior Member woodsman's Avatar
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    Quote Originally Posted by irk_miller View Post
    Childish? How in the hell did racing begin in the first place? This site has a message function. Let's race. I like racing. Been doing it since I was eleven and it's fun. I mean, everything we build is supposed to function like a race bike, and supposedly you guys are the best at building race bikes.

    Anyway, for years the second fastest lap record on Mid-Ohio was done on a Supermoto... against super bikes.
    I think you're taking several posts and blending them together.

    I posted the "childish". I assume from your "message function" comment, that I/we am/are to contact you and set the time for the duel? You should know I'm 60, still quick and I really don't give a shit how fast you may or may not be.

  10. #29
    Senior Member Geeto67's Avatar
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    Quote Originally Posted by irk_miller View Post
    Anyway, for years the second fastest lap record on Mid-Ohio was done on a Supermoto... against super bikes.
    Lap time, bike, and rider please? I would be really curious about this.

    Keep in mind that the fastest (unofficial) of all time record of Mid Ohio right now is 64.1962 seconds @ a pace of 126.624 mph by the #12 Penske indy car set in 2016 and that same team set an official record during a race of 1.03.87 minutes.

    I would say the average of a middleweight AMA sportbike (600cc) is about 1.30 around Mid-O. I can't seem to find the race results for supermotos that ran at VMD, but I think my failing memory had them at closer to 2min.
    Last edited by Geeto67; 04-29-2019 at 02:48 PM.
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  11. #30
    Senior Member irk_miller's Avatar
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    Quote Originally Posted by woodsman View Post
    I think you're taking several posts and blending them together.

    I posted the "childish". I assume from your "message function" comment, that I/we am/are to contact you and set the time for the duel? You should know I'm 60, still quick and I really don't give a shit how fast you may or may not be.
    I'm just suggesting this as a means of proving the capabilities of a bike with a dirt frame in actual application. I know you guys know there is far more to the equation than just a frame, but I had the impression that it was being dismissed as a possibility, and claims against their ability to handle the hp or lean angles seemed ridiculous. I know through experience it is very much a practical and capable possibility. I don't expect anyone to take me up on this offer race, unless they just want to hang out and ride these roads with us, which we do most weekends during the summer.

    As far as speed records at Mid-O, I thought it was around 1.45, which would still be way off 1.30, so I have some research to do and I can't find anything to back up my claim.

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