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Battle Mountain 2019

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legs_larry View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote legs_larry Quote  Post ReplyReply Direct Link To This Post Posted: 08 September 2019 at 10:02pm
Rain stopped by this morning and unseasonably warm at 11 C.  A duff wire on the timing gear delayed the start of proceedings by 20-30 minutes but we managed almost to catch up by the 10:00 Department of Transportation deadline.  A few glitches from riders and machines too: Adam Hari (N-1) and Kazuhiro Takei (Haruka 2019) having start issues sufficient to prevent them from doing a run while Yasmin Tredell & Ken Buckley both had to pull up ARION5 mid-course with a derailed chain.  Toronto disgraced themselves by not appearing at all though they claimed to have tried to phone and tell us.  Jennifer Breet only just got caught at the finish thanks to ace sprinter/catcher Barclay Henry; Ilona Peletier decked Altair 6 approaching catch and seemed pretty shaken up, though the damage is mostly superficial.  

Andrea Gallo in Taurus was almost certainly the fastest, but timing had a hiccup and said 72mph while Andrea's GPS reckoned ~111 km/h.  Best of the rest was Rosa Bas in VeloX 9 at 64.97 mph.  The Sprocket Rocket team seemed slightly disappointed with their 52.13 mph pass, but captain Chris DeMarchi complained of too much inter-rider chat and not enough coordinated pedalling


Edited by legs_larry - 08 September 2019 at 10:03pm
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a bit ov a lyv wyr by slof standirds
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legs_larry View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote legs_larry Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2019 at 4:42am
The Sunday evening forecast was for Mighty Rushing Winds, limiting the number of starters to eight, over twelve slots.  Eight became six when Annecy scratched, having not fixed the Ilona-inflicted damage in time.  Six then became five, when Denise's backup video screen blanked itself.  Leaving Rosa as the sole rider in heat one with Andrea, Jennifer, Ellen and Vittoria in the second.  All five had legal wind speeds Big smile  Andrea was the first rider this year over 80 mph with 80.80, Rosa a 71, Ellen 68 and 64 for Jennifer and Vittoria, though the latter decked Taurus-X after overrunning the catch crew.  Barclay nearly caught her...

Early night tonight because Huge Lunch.

ETA: My photos in the "BM 2019" albums under https://www.flickr.com/photos/mr_larrington/albums


Edited by legs_larry - 09 September 2019 at 4:57am
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a bit ov a lyv wyr by slof standirds
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Yanto View Drop Down
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Yanto Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2019 at 7:27am
Originally posted by RoyMacdonald RoyMacdonald wrote:

Originally posted by legs_larry legs_larry wrote:



GN: My room is at the right end of the building for the free wifi of the Scottish Restaurant next door to be within range.


What constitutes a Scottish Restaurant in Nevada? I'm intrigued.



Give you a clue - Double golden showers (oops wrong forum) arch, also known outside the USA as the American Embassy, or where oiks spend an evening and audax riders tend to gather to refresh and sleep (until the aircon is turned down (up) to arctic temps).
Ian, racing again No 6.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote russellbridge Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2019 at 8:51pm
Dave, who do you think is the best person to ask out here about steering geometry?

We ran the 5 mile course this morning. Crashed 2 miles in at about 45mph, I'm OK, the bike a bit bashed up, but we suspect that there's a fundamental steering geometry problem with the bike that's getting worse with speed.

I've just spoken to Geoff Bird by phone who's been incredibly helpful, but anyone out here would be great too...

Thanks
Russ


Edited by russellbridge - 09 September 2019 at 8:55pm
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legs_larry View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote legs_larry Quote  Post ReplyReply Direct Link To This Post Posted: 09 September 2019 at 10:49pm
Hans van Vugt might be a good place to start, also Calvin Moes if you can find him and/or Todd Reichert, and maybe George Leone.  Don't ask Larry Lem, because he brought a bike called "Scimitar" here a few years back which "handled like a shopping cart" and was basically impossible to ride at all Smile  Or ask on the Facebook group for twenty-five conflicting opinions...

Apart from Russ' little adventure, Adam Hari also decked on a qualifying run, the inadequately-taped lid came off and the rider has a few scrapes and bruises.  Tokyo and Cal Poly both failed to launch at all; Jennifer in VeloX 9 was pulled up a mile or so from timing as she was running very slowly with, we think, transmission issues.

Fun and games at catch when Denise Koronek and Ilona Peletier came in side by side; Denise's 67.84 mph is a US Women's record, while Yasmin's 47.34 is thought to be a BRITISH Women's multitrack record and "Wild Bill" Thornton's 59.83 in his Milan SL an unofficial record for a production velomobile.  Andrea fastest again, with 75.47 with Rosa Bas doing 73.73, though the latter not with legal wind.
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russellbridge View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote russellbridge Quote  Post ReplyReply Direct Link To This Post Posted: 10 September 2019 at 3:04am
The issue that we're trying to resolve is that the steering geometry (carried over from Soup Dragon) is as per the pictures below. The front wheel pivots around a cylindrical bearing inside the small rear drive sprocket, resulting (we think) in bump steer - ie bumps in the road get translated into a steering rotation centred around the offset cylindrical bearing, rather than going straight up the steering axis (head tube) in a conventional set-up. The only way to deal with this as the rider is to hold the bars tighter and tighter as the speed increases, then compounded by the fact that you're then holding the bars too tight to relax into sidewinds.
We've spoken to other riders and they are all saying that their bikes are fingertip-light grip on the bars at 60-70mph, where as ours is death-grip at 40+ (resulting in crash...). We're brainstorming to try to resolve as best we can...






I think that the team are posting updates on Aim93 facebook and Instagram, but I don't do either of dem tings

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legs_larry View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote legs_larry Quote  Post ReplyReply Direct Link To This Post Posted: 10 September 2019 at 6:06am
Monday evening.  Too windy in the first heat, but all runs legal in heats 2 and 3.  Vittoria Spada blew a tyre in Taurus-X with a mile to go and went off into the dirt, but no damage to the rider and the bike is probably just a bit scraped up.  Bangin' 69.98 mph from Denise Koronek to up her national record again.  Faster than designer/builder Larry Lem has ever made that bike go ;D

Oh, and Rosa Bas broke Barbara Buatois' 2010 world record with a 75.88 mph,run.  And it's only Monday.  There sounds to be a certain amount of partying going on by the motel pool at the moment :thumbsup:

My Sinister Agents tell me that, as long as he can fit inside it, Todd Reichert may have a go in Peter Borenstadt's DF velomobile some time soon, just to try to be the first production vm over 60.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote atlas_shrugged Quote  Post ReplyReply Direct Link To This Post Posted: 10 September 2019 at 10:55am
Is this bump steer or bump tilt? Bump steer would be the front of the wheel moving e.g. left to right. Bump tilt would be the top of the wheel moving e.g. left to right.
 
To check for either can you stick a laser pointer onto the wheels and with the steer column clamped then apply a static weight onto the front of the bike (not the fairing). Then see if the laser dot on a wall moves with the weight applied and then removed.
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote atlas_shrugged Quote  Post ReplyReply Direct Link To This Post Posted: 10 September 2019 at 12:12pm
The below post is from Brucey (not me) who can not post to the forum because of password issues:
 
My understanding is that the front wheel has hub-centre steering but
that the chain drive sprocket to the wheel is not in the same plane as
the steering pivot, AND the chain tension run driving said sprocket
is not parallel to the steering axis.

 It may be possible to rectify the problem but not without a
fair bit of engineering.  Essentially if the problem is as I suspect
then  what is required is an additional idler sprocket in the tension
run of the chain, positioned above the sprocket  such that the tension
run in the chain is then exactly parallel to the steering axis as it
drives the wheel sprocket. Probably some thought will also have to be
given to the amount of chain wrap around the sprocket (which will be
reduced), which may require that the tensioner is repositioned too.


FWIW the steering issues may be influenced by bumps but it isn't
classical bump steer per se; even when not pedalling, there is a
secondary problem  which means that going over bumps will induce high
chain tensions momentarily  and as configured at present, they will
pull the steering too.

   Give or take a few inertial considerations, the extent of this
'pull' is limited by the tension in the chain, if the tensioner is
spring-loaded.  However if the tensioner is fixed, there is almost no
upper limit to the tension variations as the chain flaps up and down.

Thus if the whole scheme is to work with a fixed tensioner, it would
be necessary for the chain run ixiting the drive sprocket to be
parallel to the steering axis too. With a spring loaded tensioner it
is certainly desirable but it may not be essential.

Apologies if I have got hold of the wrong end of the stick altogether.
Brucey
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Post Options Post Options   Thanks (0) Thanks(0)   Quote russellbridge Quote  Post ReplyReply Direct Link To This Post Posted: 10 September 2019 at 4:21pm
Many thanks Brian and Brucey.
We think it’s bump steer rather than tilt steer ie bumps are inducing left right movement at the front/back of the wheel rather than top bottom. The rose joint in the hub axis is in the centre of the sprocket so we can’t see that any hub movement will shorten or lengthen the chain, so we don’t think that this is a factor, but I bow to people with bigger brains than I. We’ve also consulted lots of big-brains over here and all agree that yep, that’s a big problem and no, there’s no easy solution...
Wer’re currently considering a very radical solution of (Kevin please close your ears) of hacking up the baron (Dtek will be reimbursed!) and using a traditional forks front end and running a long chain to the rear wheel, all of which we think can be made to work in the existing shell. Much head scratching currently going on over huuuuuge waffle breckie - breakfast of champions...

Edited by russellbridge - 10 September 2019 at 4:25pm
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