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SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Rake and Trail /cgi-bin/YaBB.pl?num=1424120242 Message started by swing69 on 02/16/15 at 12:57:22 |
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Title: Rake and Trail Post by swing69 on 02/16/15 at 12:57:22 Stock S40: Rake: 35 deg., Trail: 5.8 in. Ryca Mod.: Rake: 29 deg., Trail: 4.75 in. Wheel Base: 57" "new" Norton 961: Rake 24.5, Trail: 3.9" Wheelbase: 55.9" "new" 2001 Triumph: Rake: 29 deg., Trail: 4.6", wheelbase: 58.9 All that being said: Ryca kit definitely makes improvements over the stock S40. However, its can be tweaked to be a little more responsive in the twisties. Now, is it worth it? I dunno....stocker its a pig., but I've never ridden the Ryca version. But I've heard mixed reviews on the geometry. I guess it depends what you are used to a your riding style. I'm curious has anyone de-raked an S40? Old Featherbed nortons were 24 deg. rake., trail: ~ 4" (not exactly sure). They were known for superior handling....... Seems to me on paper the S40 (esp. in a cafe racer form); could benefit from a little quicker steering. |
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Title: Re: Rake and Trail Post by Gary in NJ on 02/16/15 at 13:24:00 Rake & trail doesn't tell you everything about a bike's handling. Things like C.G., weight distribution, cylinder configuration, reciprocating mass, rim size and tires all have an effect on handling. However with that said, most of my favorite handling bikes have been in the range of 26 degrees of rake and 4.00 inches of trail. It seems to strike a good balance of handling and stability. With the changes I've made to the front suspension of my RYCA conversion I'm anticipating that I'll be somewhere close to 26 degrees of rake and 4.00 inches of trail. I'm anticipating that my bike will be a sweet handler with a nice ride. I do want to find some alternative shocks from what are in the RYCA kit that will give me a bit more stroke and adjustability. Once properly sprung, the CS-1 should be a great carver. |
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Title: Re: Rake and Trail Post by swing69 on 02/16/15 at 14:13:36 How do you figure that you are picking up another 4 degrees o de- rake? I think 24.5 and 3.9 trail is optimal. Feather beds got triumph, harley, vincent.....you name it engine swaps. All were simular improved. I think it can be done with a top backbone cut and down tube heat bend. |
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Title: Re: Rake and Trail Post by swing69 on 02/16/15 at 15:00:28 https://www.youtube.com/watch?v=Fpj2Ct8eJ4k professional? rule number 1; Safety. No safety glasses when grinding????????? sheesh..... no gloves? even when TIG welding. I couldn't even finish the vid. Not to mention, he didn't even cover the engine from the grinding swarf! |
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Title: Re: Rake and Trail Post by Dave on 02/16/15 at 15:12:59 I just went out and measured my Cafe' conversion that is RYCA inspired and does use a lot of RYCA parts - but the forks are tweaked a bit as I used Suzuki RM400 fork yokes to cut back on the offset between the fork tubes and the steering head.....which may have not been a great idea as it has increased my trail. I also installed a 1/2" spacer to cut down on the fork travel a tad and add some preload, and I dropped the fork tubes about 1.5"....the forks are dropped as far as I can go and when they bottom out the bottom fork yoke is just a tad short of hitting the fork seals. My initial sag of the forks when in the riding position is 30mm. When I push the bike down into the "resting" position with the bike weight, I have a fork angle of 28 degrees and a trail of 5". This trail is more than you will have with the RYCA yokes as the stoke yokes have an offset from the steering head to the fork tubes of about 2.5" - while my yokes have an offset of only 1"....but because of the 28 degree fork angle that 1.5" offset is reduced to the approximately 1" difference between my bike and the RYCA with the stock yokes. With the 5" of trail my bike is extremely stable and holds any line well - however the initial force from going straight to turning.....is kind of stiff. MMRanch rode my bike and said when he went into the first turn he thought he was "trying to bend a board! I don't think it is that bad, and I don't notice that it turns any stiffer than my ST1100 - but it is not as nimble feeling as my 250 Ninja. I promised Gary a few weight numbers. With my bike unloaded the front weight 154.2 pounds, the back 173.4. When I get on the bike it is a bit hard to hold the exact same posture for both times I need to sit o the bike and move the scale from front to back, and release the jack and hold on to a ladder to balance - but with me on the bike the weight was 218.4 on the front and 280.4 on the back...which works out to be within 4 pound difference of the 175 that the scale said I weigh tonight (lots of warm clothes on). |
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Title: Re: Rake and Trail Post by Kris01 on 02/16/15 at 15:29:50 I had to look this up: http://www.totalmotorcycle.com/school-SectionFiveB.htm http://www.totalmotorcycle.com/pics/rakeandtail.gif What makes one motorcycle turn better than another one? What is heavy steering? What is rake and trail any ways? Rake is the angle between the headset tube and a vertical line. Increasing the rake will move the front tire farther from the bike. Rake is measured in degrees, and is a frame specification. To visualize trail, draw an imaginary line along the path of the headset tube to the ground. Measure from this point to the center of the tire patch. This is trail, and is measured in inches. The amount of rake is significant in determining a motorcycle's handling characteristics. In general, more rake provides greater straight line stability, less rake makes the bike more responsive. Larger values of trail also create more straight line stability. This is why the forks on a sportbike are more vertical than those of a cruiser. |
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Title: Re: Rake and Trail Post by swing69 on 02/16/15 at 15:56:38 Kris: basic and accurate. Lots of guy merging modern sportbike front ends and wheels on old style (prior to 1980 - with 28 deg. rake) triumphs get themselves in a little bind. There is very little offset with sportbike trees, due to the very steep rake (<23 deg. at times) of the sportbike frame. This puts alot more trail into the ole Triumph. so they wind up with a sportbike look that won't handle worth a crap. I think a 24 deg. rake; 3.75-4" trail would do the Ryca justice....as long as some dive can be limited from the front stock forks so the trail doesn't shrink too much under braking. |
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Title: Re: Rake and Trail Post by Dave on 02/16/15 at 15:58:07 I also believe we are putting too big/wide of tires on the Cafe' conversions. The 130/70-18 tire that we are squeezing onto the 18x2.50 rear rim is made for a 3.50 inch wide rim. When you squeeze that wide tire on a 2.50 inch rim the tire becomes pinched in width and the tread becomes too curved in cross section, and tire width when mounted is only 116mm. The 100/90-18 front tire fits fine on the 18x2.15 rim - but it is a bit tall in the sidewall and in some good performance tires you can't get a tire in that size. To make the bike more nimble and better handling - I believe it is better to run a bit smaller tires. Currently I am running a 110/80-18 rear tire on the 2.50 inch wide rear rim, and a 90/90-18 on the front. They seem to work just fine and I have never felt that they are too narrow - although after having looked at the bike with the bigger/wider tires for the last 2 years the new size does look a bit smaller - but not out of place. I also have mounted a 18x3.50 rim on a Savage hub and mounted a 130/70-18 tire and will try it this summer - and I believe I will try a 100/80-18 tire in combination for that wider rear tire/wheel. I suggest that if you are using a 2.50 inch wide rim - use a 110/80-18 tire as it is made for that size rim, and it is only 6mm narrower than the 130 tire when it is squeezed onto a narrow rim. And also consider the 100/80-18 front tire as it is less tall and will help to increase your fork angle when the front end is a tad lower. |
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Title: Re: Rake and Trail Post by Flint on 02/16/15 at 17:43:54 The Harley XR 750 had 24 degrees rake and 3.75" trail. That seems to be the winning combo for a scrambler. |
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Title: Re: Rake and Trail Post by Kris01 on 02/16/15 at 18:26:33 http://www.tonyfoale.com/Articles/RakeEx/RakeEx.htm Your text (with pics for clarification). |
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Title: Re: Rake and Trail Post by KennyG on 02/16/15 at 20:54:16 As far as handling goes, the best handling bike that I ever owned was a 1973 Norton Interstate. When I picked up the Norton at the dealer in London, both tires were 4.10 x 19" Dunlop. At some point when the Dunlop tires wore out I purchased Pirelli tires and they improved handling. Later on when the tires needed to be replaced I used Pirelli tires again, but I went with a more narrow tire on the front and a 4.10 on the rear. Handling noticeably declined. The next tire change I used Pirelli size 4.10 on both the front and rear and the handling was absolutely great. One other observation about the Norton, both front and rear tires wore out at the same time. I rode the Norton for over 30 years so it was easy to know what worked and what did not work. Most riding was done on two lane asphalt roads with a speed limit of 50 to 60 MPH. Kenny G :) |
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Title: Re: Rake and Trail Post by Dave on 02/17/15 at 03:11:11 I believe you should ride the converted Cafe' before you start changing the rake or trail...you may like it fine. My bike with the additional trail most likely does ride a bit stiffer as a result - but it is not hard to ride, it is very stable, and it is a lot of fun. This morning I read a review in Cycle World about the BMW S1000XR ADV bike. They commented: "Thanks to 25.5 degrees of rake and 4.6 inches of trail, the S1000XR had agile steering geometry." Those numbers are not not all that far off from what the RYCA achieves. Several RYCA owners have commented when riding their bikes for the first time that the bike felt "twitchy"....and one rider even belt insecure at speeds over 45mph. I believe that most of this is the drastic change from what the bike rode like in stock form...vs....the way it handled as a Cafe". I have seen one bike that a fellow altered the rake...mogman. The bike is not yet finished....here is a photo mock up of what he is working on. He stated the rake was reduced by 10 degrees. Not sure how the decrease in rake combined with the large rear tire works....bikes built for going through the corners briskly generally have much less mass in the rear wheel/tire. |
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Title: Re: Rake and Trail Post by swing69 on 02/17/15 at 08:35:45 Thanks for the "fix" Kris on the link. A 10 degree correction from stock (35 deg. and 5.8") would bring him down to 25 degrees, and ~3.75 trail. I think those would be great numbers. under braking, those number reduce more. The New Norton "sport" 961 has similar numbers (24.5 deg., 3.9" trail 55.9" WB)....but that's a street bike. I think they may be have more trail (4.6") due to signifigant fork compression which will really reduce trail! A streetbike ideally has less compression, therefore a more stable trail number. I'm starting to be convinced, that with the upcoming Ryca strip down, I'm going to reduce the rake another 5 degrees from the Ryca numbers. I've got to do a little thinking on this. A 5 or 10 deg. correction is do-able, but if "undoing" the Ryca correction, I'm not sure how the bodylines would change. If they do, how much. I think "mock" ups is the only way to tell. |
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Title: Re: Rake and Trail Post by Serowbot on 02/17/15 at 08:59:48 Too little trail and you'll need a steering stabilizer to go over 50mph... You'll get speed wobbles on accel and decel... That won't make you faster... I would do the convert,... see how it behaves, then think about whether you want any more changes... These changes won't be easy to reverse... |
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Title: Re: Rake and Trail Post by swing69 on 02/17/15 at 09:52:22 Nah...no worries. look at the CBR600 numbers. The typically do not have steering dampers and don't go into a death shake at 50+ mph. However, a damper is a good precaution! mid 1980 sport bikes (ducati's) had them stock real world number sample: Typical Cruiser Dimensions (2003 Honda VTX1800) Rake 32.0 degrees Trail 152.0mm (6.0 inches) Wheelbase 67.5 inches Therefore: With a rake of 32 degrees and a trail of 152mm (6 inches) this motorcycle will be better and more stable in a straight line than turning a tight corner. The long wheelbase of 67.5 inches also assists this motorcycle again in straight line performance but will hinder it in cornering. So this motorcycle has been properly designed for it's intended purpose (touring, cruising, and highway use). Typical Sport Bike Dimensions (2003 Honda CBR600RR) Rake 24.0 degrees Trail 95.0mm (3.7 inches) Wheelbase 54.7 inches Therefore: With a rake of 24 degrees and a trail of 95mm (3.7 inches) this motorcycle will turn much quicker and sharper than the Cruiser, but will not be as good or as stable in a straight line. The short wheelbase of 54.7 inches also assists this motorcycle again in cornering but hinders straight line stability. So this motorcycle has been properly designed for it's intended purpose (going in and out of corners at high speeds and taking twisty roads). |
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Title: Re: Rake and Trail Post by swing69 on 02/17/15 at 09:53:35 Unless of course; I don't touch this bike. Sell it, and start from scratch with another donor bike. Thats always possible. If I do that, I have a blank slate. |
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Title: Re: Rake and Trail Post by Dave on 02/17/15 at 10:03:12 Swing69: I know you are going stir crazy up there with all the snow....but slow down a bit on this bike and don't be in too big of a hurry to cut it up. You just got the bike, I haven't seen anything that indicates you have been able to ride it yet to know how it handles. It looks like you could spend a day or two fixing up the bike to get it on the road, and then have a full summer of riding to learn what you like and dislike about the bike. http://suzukisavage.com/cgi-bin/YaBB.pl?num=1422756049/0 It will run all summer on the belt no problem...then you can decide if you want the chain (Going to a chain will require you to modify the footpeg bracket for clearance). http://shop.rycamotors.com/chain_conversion_kit.html And cutting and shortening the swing arm....not a good idea...but that also is another project for another year if you decide you have to do that to get the look and ride you want. http://suzukisavage.com/cgi-bin/YaBB.pl?num=1422924199/0#0 And cutting the frame and changing the rake and trail.....you really need to spend some time in the saddle before you decide you have to do this. My bike may turn a bit stiffly when entering a corner - but I can tell you I have learned to appreciate that stability when traveling down the divided highway at 70mph and passing semi trucks. The stock RYCA does not handle poorly - they are fun to ride and more nimble than the Savage in the stock form......although they are not a sport bike and will never handle like one. They ride much like the 60's bikes that the Cafe' bikes were originally built from....and that is just fine with me. With Gary's help we may be able to learn how to optimize the forks and shocks for a better ride and handling....without cutting anything up! |
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Title: Re: Rake and Trail Post by swing69 on 02/17/15 at 12:27:26 Hey Dave, I think out loud, forum fun really. Nice to get input from others. I can tell you that the Swing arm cut isn't necessary, the wheelbase is fine. The rake and trail is what gives a visual "key" that there will be a riding problem. I don't need to ride it to tell that it will turn slow, better than a stock S40, which I have ridden....but still, slow. I've easily owned, ridden over 100 different bikes. Mid 50s, to mid 2000s. currently own maybe 9 (depending on how you count carcasses) I've built several hybrids, different engine, forks, mods...you name it. Over analyze? yup. leave well enough alone, not usually, ruin stuff? sometimes. Have fun, all the time! :D Here is a Benelli Mojave, Honda powered that is a daily driver for me. |
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Title: Re: Rake and Trail Post by swing69 on 02/17/15 at 12:32:28 commando powered featherbed Norton? built that. rebel engined triumph 250, built one. Lifan powered "Fox" minibike? yup. As you can see; I have a mental issue and usually don't leave much "as built". I enjoy modifying stuff. Another addition? mechanical anti-dive front end linkage for the Ryca? Thinking about that! |
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Title: Re: Rake and Trail Post by Serowbot on 02/17/15 at 12:54:13 Nice shop,.. mine's a glorified shed... ;D... http://suzukisavage.com/yabb2.2/Attachments/small.JPG |
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Title: Re: Rake and Trail Post by swing69 on 02/17/15 at 14:48:24 I wish it were mine too! that's my work shop. My home is just reg. 2 car with a shed. Carcasses are rolled into the basement for surgery. Some stuff winds up at "work". depending on what needs to be done in a short time frame. Still, yes....nice to have space. |
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Title: Re: Rake and Trail Post by swing69 on 02/18/15 at 14:02:31 RYCA in the Market place. You guys can make the decision for me. If it sells, I will cut up a "new" donor rather than a Ryca. If it doesn't.....the Ryca will be "finished" Pun intended??? lol Partial trade accepted for a stocker, or ever a abandoned project as long as its a good running lower mileage machine with title. see the ad. Pm if interested :D :D |
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Title: Re: Rake and Trail Post by mogman on 02/21/15 at 18:37:41 Regarding post #11....A Ducati 900 Supersport has a 24 degree rake and 3.0 inch trail. The Buell XB9S and XB9R are what I ride on and off track, are at first scary but turn in fast and are able to apply speed coming off the apex allowing the rider to actually run up the inside and add power exiting the turn. The cafe (pictured) is 24 degrees and 3.1 trail as shown and will be stripped of anything I can throw in the bin. I got the bike as an orphaned $800 bobber and set Mike to work on it for the fork rebuild (-2") and the rough in of the steering tubes. An expert jig weld guy named Rob did the rework of the neck without separating it from the backbone. Video running after the forks were dropped. https://www.youtube.com/watch?v=D-oejcNmeuc&feature=youtu.be If and when one gets use to such a Buell rake structure, the track day gets most interesting. For now I am at a stop on the Savage to consider the foot pegs for my 170 pound, 6'-3" body and some easy tank mods. This is not to be a show bike but instead as simple a bolt-up job anyone can make (except jig-weld neck). It will be fuggly and built for the track. Oh, on the Buell 52" wheelbase, 21 degree rake, 3.3" trail I have run 135 mph without a steering damper and no head shake. :o |
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