BRIDGESTONE TIRE TEST, THUNDERHILL RACEWAY PARK
To order this tire online, go to: http://viets-performance.com
DATE: 8/25/2010
TEMP: 108F ambient, surface at 140F
BIKE: 2009 Yamaha R1, 5,000 miles on the odometer
previously owned by Ken Hill of Ken Hill Coaching and Yamaha School of Champions
At the start of the test I had one hour of track time on the bike to ride around at pace and familiarize myself with my first 1000cc track bike. The new tires were put on by Viets Performance at Thunderhill during a private day hosted by Lance Keigwin of Keigwin’s at the Track.
Bike settings:
- 2008 R1 forks set flush with the 2009 upper triple clamp
- Ohlins 25mm cartridges installed, valving C5 and R3
- Fork springs 1.0kg in both legs
- Fork oil standard Ohlins oil set at 165mm air gap
- Preload at 9 turns in
- Rebound at 12 clicks out
- Compression at 9 clicks out
- 2009 stock R1 shock with stock spacer in place
- Preload at 3 turns back from max
- High speed compression at 1 turn out
- Low speed compression at 5 clicks out
- Rebound at 12 clicks out
- Gearing is stock., stock chain, rear axle position standard,
- Bridgestone Battlax YCX front 120/600×17 set at 26 cold, round version NOT the V
- Bridgestone Battlax YCX rear 190/55×17 set at 20 cold
Session 1:
This was a 4 lap scrub in period. With the track temps being so high, there was plenty of heat in the ground to get the tires hot quickly. Each lap was quicker, focusing on the following:
- lap 1 straight line braking and acceleration
- lap 2 trail braking and mid corner throttle
- lap 3 corner exit acceleration
- lap 4, fast lap at 90%
Once the 4 laps were completed, the in lap was the same pace as lap 4. The pressure gauge was calibrated earlier to ensure accuracy. Upon entering the hot pit, the bike was parked quickly and hot pressures set at 30 psi front and 26psi rear.
Session 2: (started immediately after tire pressure was set, total 8 laps)
The goal of session 2 was to evaluate tire structure under aggressive braking re steering. With the 30psi hot pressure, would the tire hold up structurally so that I could steer the bike not only going into the corner apex, but also during initial  trail braking. During aggressive straight line braking in turns 5, 9 and 11, the front tire seemed ‘round’ allowing easy transitions to trail braking but failed miserably on brake dive. One turn of preload was added to the front forks which took away the initial brake dive problem and compression and rebound settings remained unchanged.
Session 3: (started immediately , total 8 laps)
The goal of session 3 was to assess mid corner stability and turn 2 was the corner of choice. Entry speed was a little too fast allowing the front tire to scrub speed, but the throttle was set for a constant radius arc to assess handlebar action side to side/rowing. After a couple of passes through turn2, changes needed to be made especially with the high speed bumps in 2, 5 and 9.
The shock changes were HSC to 1.5 turns out, LSC at 5 clicks out and preload set 2 turns softer at -5 from max. No changes to the forks.
During this session we had the beginnings of a front tire tear:
Note the removal of material from the tire at the dept indicator moving out towards the edge of the tire. Thinking that perhaps the tire carcass may be folding a little, we changed the pressure to 32psi hot.
Rear tire was showing good wear after the changes made, but too much weight on the rear of the bike was accelerating the wear of the tire.
BREAK TIME for hydration and recollection of thoughts – 15 minutes
Session 4: (2 warm up laps on the tires and 6 fast laps;- total 8 laps)
The goal of session 4 was aggressive trail braking to assess front tire tearing and see if we could clean it up by manipulating preload only with the increased tire pressure. We started at max preload and came back 1.5 turns each lap.
With max preload the bike wouldn’t change lines anywhere unless the throttle was closed. As preload was reduced, the chassis became more neutral and could be made to change lines but still required forceful input on the bars. At 5 turns back from max preload, the tire seemed to clean up while giving excellent feel during trail braking in turn 14. However, the tire tear was still present, therefore we decided we needed to make a geometry change to the bike, mostly based on accelerated rear tire wear.
BREAK for shock removal and 6mm spacer insertion (took lunch)
To do this we had to run into town to get a 22mm open ended wrench for the clevis nut. Once that was secured, the bike was raised on foot peg stands and the top shock mount bolt loosened. The rear stand was used to support the swing arm as the clevis nut was removed and the top shock bolt removed. Spacers were placed on top of the OEM spacer, making a total ride height change of +7mm. The shock was secured, all nuts and bolts tightened and everything double checked. Forks remained in the same position as a control.
Session 5: (2 warm up laps on the tires and 8 fast laps;- total 8 laps)
The goal of session 5 was to reassess mid corner stability given the geometry change with increased swing arm angle and a balance point change in the chassis. Turn 2 was again used for this test, with same corner speed entry and same throttle position during the turn. Turn in was much improved with much less effort required and the mid corner line corrections were much easier to make. However, the chassis would still not finish a corner unless leaned on heavily.
The rear tire wear improved dramatically, showing much less wear while giving excellent feel on corner exit re grip and tire contact with the ground. The graining/sandy beach pattern on the tire indicates optimal wear, but there was still evidence of either a heat problem or suspension setting issue close to the edge of the tire that needed to be addressed next.
Session 6: (total 15 laps)
The goal of session 6 was to ride the bike at an increasingly faster pace, using the same testing criteria as in earlier sessions to assess braking/steering, mid corner stability and corner exit drive. In running a high number of consecutive laps that would also allow me to get a great feel for the carcass movement under all skill execution conditions.
At the end of the 15 laps, the rear tire wore equally as well if not better with sustained and more consistent skill application re lines, braking and throttle control. The tire tear in the front tire became marginally worse, but not enough to show a visible difference to the tear photo provided initially.
For the testing period, that was 51 laps x 3 miles = 153 miles.
Note that further testing was done with Leo Vince’s Manny Hauswirth for an additional 22 laps (66miles) before the R 1 was parked for the day.
DAY 2: Thunderhill Park, River City BMW day
DATE: 8/29/2010
TEMP: 80F ambient, surface at 115F
Forks:
- Preload at 9 turns in
- Rebound at 12 clicks out
- Compression at 9 clicks out
Shock:
- Preload at 3 turns back from max
- High speed compression at 1 turn out
- Low speed compression at 5 clicks out
- Rebound at 12 clicks out
NOTES:
- the track was split until 12.30am into an East and West configuration for the BMW riders to give them an easy introduction to the track layout.
- 20 minute sessions with a 10 minutes slush time to clear the track and line up the next group.
- After lunch at 1.30pm the track was reconfigured for the 3 miles full course and A and B groups went out for their own sessions.
- At 3pm the track format was an open track – any one any time from all groups.
- 66 laps x 3 miles – 198 miles on the tires to date
Session 1:- assess traffic and warm up
- out in the A group and see what pace in general was being run. Started on the longer East loop (turns 1-6 and exit at T7 onto the front straight).
- Set hot tire pressure after 5 laps and went back out for a total of 14 laps (26 miles)
- Traffic was very slow and understandably not predictable as for many riders this was their first track day.
- Sat out the morning as there was nothing to be gained other than a pleasant breakfast, cup of coffee and some bench racing over the second cup of coffee.
Session 2: (after lunch for a total of 10 laps in a 30 minute session)
The goal of session 2 was to see how much travel I was using in the front fork from aggressive straight line braking. A zip tie was set snug and after 2 warm up laps hard straight line braking was executed in turn 5, 9 and 11.
- after a total of 4 laps, the zip tie was within 3mm of bottom out, so 1 turn of preload was added
- two laps later, the zip tie was in the same spot, so 1.5 turns of preload was added and 2 clicks of compression
- two laps later the zip tie was 5mm from bottom out so ½ a turn of preload was added and one click of compression
- 2 laps later at the end of the session the zip tie was 8mm form bottom out
Session 3: (total of 10 laps in a 30 minute session)
The goal of session 3 was to work on trail braking based on feel once the braking forces were diminishing as the lever was released
- compression was set at 5 clicks out from full stiff and then removed at one click per lap over 6 laps
- at 5 out there was no feel, the bike ran wide, and neutral steering was lost
- at 9 clicks out high speed bumps were very felt very firmly through the bars
- at 11clicks out there was too much suspension action over high speed bumps
- final compression setting was 9 clicks out
- rebound was reset to 10 clicks out for better reaction to the high speed bumps and finally set to 8 clicks out
Session 4: (total of 20 laps for long duration run and tire wear evaluation).
- goal for session 4 was two warm up laps and then 18 laps at 2:04 pace each lap if at all possible given traffic and passing opportunities (outside only in corners)
Tire mileage and condition
- day one 73 laps x 3 miles – 219 miles on the tires to date
- day two was another 146 miles
- total miles 365
