Ideal Geometry?

[br4nd0n]

I wanted to get some input from some of the racers and what they feel would be the ideal geometry for the MT-07/YZF-R7 if everything could be changed except the motor.

What would the rake, trail, and wheelbase be?

[M, Hausknecht]

I haven't bothered to measure the rake, trail or swingarm angle on my 07 race bike and neither do most racers. I can tell you, however, what parts I have and why. I should also note that there is no such thing as "ideal geometry" because what works best for any particular rider will vary from other riders also running the same pace. And then some riders will make minor geometry changes that are track-related. Sure, there isn't a lot of variation but front end "feel" is crucial to riding at or near the limit, and that is why the variation occurs.

Before getting to geometry, we need to address tires. The best race tires are Dunlop and Pirelli slicks. Except for occasionally available Pirelli SC1 180/55 rears (imported to the U.S. specifically and primarily for the Kramer Evo2), you'll use either a 180/60, 180/65, or a 190/60 rear tire. All are larger in diameter than the stock rears, so they raise the rear ride height appreciably. The stock swing arm angle isn't ideal, you want more angle, so most competitive racers are using a longer rear shock than stock, plus shock linkage from Robem or AP MotoArts. I have a K-Tech DDS Pro (length is around 315mm) rear shock and the later version AP MotoArts shock linkage. 

With the back jacked up a bit, you then need triple clamps with 24-28mm fork offset to get some reasonable trail. I've found 26mm of offset to feel right for me. The bike turns in well, doesn't require mid-corner adjustments to keep it on line, and it finishes corners well. It shakes its head a bit when the front wheel is light but it is manageable, with a steering damper, and a trade-off for a fairly quick turn-in. I have Robem triples, with replaceable inserts for varying offset. Attack Performance also makes quality, adjustable triples. You'll likely end up dropping the forks a bit in the triples, to raise the front compared to stock, but the amount you'll measure between the top of the triples and the end of the forks depends on the triples you're using. With the Robem triples and stock size forks, I've run between 3/4"-1" between the top of the upper triple and the top of the fork tubes. It is a tuning variable. 

I've not found wheelbase to matter to me but I've never gone to either extreme. I tend to stay within the middle of the range, running 15:42-44 at most tracks, and I have a 16 tooth driver just in case. Gearing changes can lead to small shock damping changes due to the more or less leverage on the shock by the longer/ shorter swingarm, but that is just typical minor adjustment stuff you do every day anyways.

The biggest challenge faced my the MotoAmerica Twins Cup competitors running the R7/07 is front end chatter with the latest Dunlop slicks. It doesn't appear to be a geometry issue. Frame bracing isn't allowed by the rules and the consensus seems to be the frame is just too wimpy around the head stock, and also all the way to the swingarm. Blake Davis, now two time champ on an R7, uses R1 forks (stiffer than most generation R6 forks) that have been lengthened internally. He also doesn't weigh much, so he has appeared to suffer less from chatter than some others on the R7.

I hope this is helpful, although not quite responsive to your inquiry.

[br4nd0n]

Thanks for the response.

I'm totally fine with riders giving what their ideal setup would be for a majority of the time. I'm more or less curious to see if there are any numbers etc. that seem to be more common.

[M, Hausknecht]

1 hour ago, br4nd0n said:

Thanks for the response.

I'm totally fine with riders giving what their ideal setup would be for a majority of the time. I'm more or less curious to see if there are any numbers etc. that seem to be more common.

Do you have the ability to reliably measure rake and trail? Of so, could you briefly explain how you do it?

[cosp600rr]

If your on an MT/FZ-07 and have the stock forks I have Robem adjustable triple clamps for you. 

Oh and I agree with everything M, Hausknecht said about the set up. Mine also has a Ktech shock with the Robem link on the rear and had the adjustable triple clamps on the front. These clamps will make a big difference in how the front feels and how the bike turns. Let me know if your interested. 

[M, Hausknecht]

I have the same triples. Allow adjustment of trail and they are very well made.

[supertwin_37]

I’m also in this same boat as to what’s a good base line number of geometry. I know it’s everyone’s secret sauce and riders are different. Just wanting to get a base line.

The bike is 2016 FZ, AP dropped triples, 2012 R6 forks, Ktech 35DDS rear shock, and Robem current link they offer. 
There site suggests 290-300mm shock length with that link. Sounds about right?? Also the forks caps are sitting flush with the AP dropped adjustable triples. Again just looking for a base line of some sort.

 

Edited January 30 by supertwin_37

[bockscar]

Curious what raising the swingarm and changing the angle gets you? More anti-dive? How does that change make the bike fast at the track? 

[M. Hausknecht]

14 hours ago, supertwin_37 said:

I’m also in this same boat as to what’s a good base line number of geometry. I know it’s everyone’s secret sauce and riders are different. Just wanting to get a base line.

The bike is 2016 FZ, AP dropped triples, 2012 R6 forks, Ktech 35DDS rear shock, and Robem current link they offer. 
There site suggests 290-300mm shock length with that link. Sounds about right?? Also the forks caps are sitting flush with the AP dropped adjustable triples. Again just looking for a base line of some sort.

 

OK, so the Robem triples and shock linkage are intended to be used with a 180/60 rear tire, which is measurably taller than the stock 180/55 rear. I've got my shock at 310mm but I'm using Robem triples (either 26 or 28 mm offset) and AP rear shock linkage. The R6 forks are shorter than the stock forks, so the most competitive 07/R7 racers in the U.S. are using R1 forks that are lengthened a bit either internally or externally (they are stiffer than R6 forks). What you've got is probably close enough as a place to start but your front may be a bit too low unless your rear is also lower. 

[M. Hausknecht]

7 hours ago, bockscar said:

Curious what raising the swingarm and changing the angle gets you? More anti-dive? How does that change make the bike fast at the track? 

The stock geometry swing arm angle isn't steep  enough to provide sufficient anti-squat under hard acceleration. This means the back of the bike settles excessively under acceleration, resulting in less steering head angle and more trail, and less weight on the front tire. As a consequence, the bike may need additional steering input to finish a corner under acceleration or it may just drift wide from the front, forcing you to reduce throttle at a particularly bad time. 

 

[supertwin_37]

2 hours ago, M. Hausknecht said:

OK, so the Robem triples and shock linkage are intended to be used with a 180/60 rear tire, which is measurably taller than the stock 180/55 rear. I've got my shock at 310mm but I'm using Robem triples (either 26 or 28 mm offset) and AP rear shock linkage. The R6 forks are shorter than the stock forks, so the most competitive 07/R7 racers in the U.S. are using R1 forks that are lengthened a bit either internally or externally (they are stiffer than R6 forks). What you've got is probably close enough as a place to start but your front may be a bit too low unless your rear is also lower. 

So my triples from AP are a step down and i think 20mm is number they’re step down to from the top triple clamps to give it that length your talking about. The rear shock is at 305mm do to im guessing the newer generation Robem link as stated on there site. Just if someone had a top triple clamp to center front fork axle measurement as a ball park would be nice. And if someone else on here is running that rear link and if 300ish mm sounds about right on shock length. 

[supertwin_37]