Reading several current posts today, I have a question which relates. What kind of downhill speeds have people reached on Richter Pass and Yellow lake? I get the high speed wobbles on the P3 with a front wheel Zipp 404 tubular, but not with a clincher (around 45 mph, 650c for the record). I don’t want to give up the 404 for the rest of the course and I hate the thought of using brakes in a race. Yes, I’m on the bullhorns and weight slid back with the Zipp (from about 36 mph on up). The clincher I ride on the aerobars to near mid-forties with no problem.
Coming down off Yellow Lake and back in to town I hit 54mph. This was on a P3 (650) with tubular tires and on the aero bars. The bike was rock solid without the hint of a problem. The only problems I know of that will cause that problem on a P3 are: 1) a mismatched fork, 2) loose head set assembly, or 3) some other component/ maintenence issue. Since it happens with both training and racing wheels I doubt they are the problem. I would sure investigate and solve that problem before the race.
Good luck and best wishes - you’ll love IMC!!!
Back in 1995, when you descended from Yellow Lake to OK falls I got up in the 80+ kph range at IMC. My question to you is why you get a speed wobble with a Zipp 303. Clearly your frame is not the issue as the frame works fine with the clincher wheel, so its the 303 wheel or the tire you have mounted on it or the combination of the two with the frame causing a weird harmonic. Either way, you can change the natural frequency of the frame+303+tire combination by clamping your top tube of your bike with your knees as you descend just as the speed wobble starts and then you should be able to pull through. Either way, I’d talk to Zipp about why it happens with the 303 and not your clincher wheel. I used an old Zipp 440 from 1993 till last year, and got up to 90 kph with that wheel on my Kestrel 200 with no issues.
Dev
Since you’re using tubulars, it could be the tire causing the problem. If it isn’t mounted correctly (straight and true), or if it has a bulge or hop near the valve as some have, then that could do it.
Joel
I think my PB for Yellow Lake was close to 90 kph, can’t say I was looking at the speedo at that speed, certainly over 85. Doubt I’ve gone much over 80 kph coming off Richter.
If you have concerns then I’d advise you to ‘roll’ Yellow a few times pre-race. I did that in 2002 (4x) and each time I was more relaxed and faster. It’s a bit of free speed.
Now if I could just learn to corner…
g, IMC99-03
Dev - I talked with my LBS guy today and he had the same thought. He was going to go and call Zipp and ask a few questions. David missed my comment that the clinchers, which are the Velomax rims provided by Cervelo as stock, doesn’t result in the wobble. The fork is also the standard P3 (2004) fork supplied by Cervelo. If 50 is around the upper limit, then I don’t think I would be losing that much time if I were to touch the breaks a time or two.
One last question Dev, I thought I was maybe going to run into you at IMC, but I checked the participant list and didn’t see your name. I guess this means maybe next year at Tupper Lake? At least by then I should have my TSR gear. I suspect that, then, I may finally stand out in a crowd.
I’m not sure concern is the correct word. I let it go on the last downhill at Tupper Lake in New York and was wobbling down the middle of the lane at around 46 mph, didn’t use the breaks as it is a straight run out. I did “intimidate” a couple of other riders I think, as they seemed to move over to the inside of the shoulder, as I passed. I think I might have been more entertaining than anything else.
I will get to Penticton a week before the race, and I’ll give the Yellow Lake descent some practice. 50 mph free speed after 90 miles on the bike - ya just can’t pass that up!
"David missed my comment that the clinchers, "
Actually I didn’t miss that…I interpreted your post that it didn’t happen until 45 with the clinchers. I went back and read it, and I think that I misdangled your modifiers (“The clincher I ride on the aerobars to near mid-forties with no problem”)- sorry about that. Anyway, I agree to get the Zipp looked at.
Again, best wishes,
david
IMC 96, 97, 98, 02
I had my bike shop glue the tire on. My first real race wheel and I didn’t want a totally amateurish looking glue job which I do with amazing regularity. To boot, the tire is a 22mm Continental, which the LBS talked me into (vs a 19 mm) after hearing about my bike handling skills. Yes, I think I can easily put Gordo to shame with respect to who has the pooper cornering skills. That said, though, the front tire looks like a mountain bike wheel when I’m riding. I can’t wait to flat it so I replace it with the 19mm. To answer the question, the tire is mounted on dead center and no bumps. Back to the drawing board for me.
In May I hit 86.4km comming down from Yellow lake in aerobars with training wheels. Richter Pass maybe 70ish due to the wind.
Sorry David, I leave a lot of stuff dangling. Actually, the max speed I have reached on the clinchers is about 44-45. Everything is rock steady unless there is a cross wind going and then I just push back against the wind. I suspect that I could ride 50 with no problems on the clinchers if I found the right hill.
Thanks for the best wishes. I finished my last hard ride yesterday (136 miles and it felt good!). Now, I start tapering and getting excited. Staying at a B&B about a mile from the transition area, flights are booked through Vancouver, and I have a week to acclimate (and probably even get bored) before the race. Any pre-race activity suggestions for the Penticton area? I will drive the bike course in its entirety. I’ll bike the run course, and practice the Yellow Lake downhill once or twice, maybe watch a few DVDs and read a book or two. I have the 2002 and 2003 IMC race tapes. I could possibly watch them for the 60th or 70th time. Always fun to see Gordo’s salute from last year’s finish. 
Several things that I always do pre IMC really get me ready. I visit the local wineries - there are lots of them - and you can just stop while driving the bike course. You can have lunch there and really relax and enjoy yourself. My favorites are Tinhorn Creek and Breezy Point. There was another on the way to Naramata and I can’t remember the name, but the lady who does the serving at the wine tasting is worth the trip! I also like just loafing around the Hog’s Breath coffee house. For some reason I relax seeing everyone else uptight. I also sqeeze a spiritual moment and for me it is the Sat night Mass (I’m not Catholic) at the big Catholic Church there on Main St - the Preist always acknowedges the IM participants and it is kinda nice.
I really love that race. Have fun and be safe!
Bigger issue up there can be wind. It can get gusty coming off Yellow Lake which at 50mph can be dicey. Go with stable bike/wheel setup and rider position.
looking at the rolf prima elan wheelset recently, around the same weight as 404 tubulars and they warned that using a tube with long valve stem could cause speed wobbles due to the light rim weight and impending imballance. They reccomended placing the speedometer magnet opposite the valve stem and possibly adding a small piece of lead tape to balance it out. 404 use a long stem +adapter… I’ve never gone over 45 on my 404 front but never had any problems yet.
which is why i ran a disc last year, i hit close to 90 coming down from richter…i’m hoping to hit close to 100 this year (km/h), tillium front, renn rear.
it’s interesting with all these posts. i did imc in 2002, and got up to 91k on richter, but couldn’t get much quicker than 85 on yellow lake. the difference for me was that richter is more or less a straight line, but yellow lack has some twists that i didn’t like much. i didn’t practice either descent tho, and on richter i could do the pantani style nose to stem position, while on yellow i was too scared to be so radical.
i usually descend ok, but i remembr just being so releived when i rolled off the yellow lake descent and saw lake skaha. man…it’s a great race, one of my favourite ironman. have fun.
Why anyone would want to try and hit 50+ mph after Yellow Lake is a mystery to me. It is always a big gamble to push it that hard on a downhill that has turns and those nasty cracks in the road filled with the goopy tar that heats up in late August and can catch your wheel. When I did IMC in 1999 I was up to around 70km/h on that descent and then I thought that I’d slow it down a bit and be conservative since it is so close to the end of the bike and a fast ride into town from there. A guy went by me in a full tuck doing at least 80km/h and about 200m further up caught his front wheel on one of those cracks in the road and was tossed over the handlebars and into the ditch. I clamped on my brakes to try and stop to help him but he popped up out of the ditch and waved me on saying he was fine (silly idiot probably crashes all the time judging by his Kamikaze descending technique) but I bet the few seconds he made up going really fast on the downhill didn’t help much for his run or the condition of his bike post race.
Dude it’s Brakes,not breaks. o:)
A guy went by me in a full tuck doing at least 80km/h and about 200m further up caught his front wheel on one of those cracks in the road and was tossed over the handlebars and into the ditch. I clamped on my brakes to try and stop to help him but he popped up out of the ditch and waved me on saying he was fine (silly idiot probably crashes all the time judging by his Kamikaze descending technique)
Hmm, maybe if I can’t master the Zipp wheel, I can get that guy’s injury repellent tri suit. If I could just bounce up after a fall like that, I wouldn’t be so worried about crashing in the first place. FWIW, I recently got a Renn disc, and will be trying it out for the first time at IMC. In for a penny, in for a pound.
Hey! At least I was one for two! LOL