All other things being equal (same bike, same rim depth), would the increased gyroscopic effect of a heavier front rim make a bike more stable and less twitchy feeling when riding on the aero bars?
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Re: do heavier wheels make bike less twitchy? [pacific]
[ In reply to ]
In theory, yes, but you would need massively heavier wheels to see a difference IMO.
Things that make a tri bike less twitchy
-weight farther back
-longer wheelbase
-lower center of gravity
-more rake and trail (not 100% on this one)
Things that make a tri bike less twitchy
-weight farther back
-longer wheelbase
-lower center of gravity
-more rake and trail (not 100% on this one)
Re: do heavier wheels make bike less twitchy? [pacific]
[ In reply to ]
Yes.
But not primarily because of increased rotational momentum about the hub axle or precession, as some might tell you. It's simply because a heavier rim+tire (rolling or not) increases the moment of inertia about the steering axis. This is noticeable when the rim+tire weight difference is medium-large. Around 100 grams is enough for most folks to feel it.
That said, I don't know anyone who adds weight to gain stability. We all want negative weight bikes. ;-)
Cheers,
Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)
But not primarily because of increased rotational momentum about the hub axle or precession, as some might tell you. It's simply because a heavier rim+tire (rolling or not) increases the moment of inertia about the steering axis. This is noticeable when the rim+tire weight difference is medium-large. Around 100 grams is enough for most folks to feel it.
That said, I don't know anyone who adds weight to gain stability. We all want negative weight bikes. ;-)
Cheers,
Damon Rinard
Engineering Manager,
CSG Road Engineering Department
Cannondale & GT Bicycles
(ex-Cervelo, ex-Trek, ex-Velomax, ex-Kestrel)
Re: do heavier wheels make bike less twitchy? [GreenPlease]
[ In reply to ]
GreenPlease wrote:
In theory, yes, but you would need massively heavier wheels to see a difference IMO. Things that make a tri bike less twitchy
-weight farther back
-longer wheelbase
-lower center of gravity
-more rake and trail (not 100% on this one)
More rake gives you less trail which gives you more responsive steering, (to a point)
Less rake give you more trail which gives you less responsive steering.
A lot of that depends on the head tube angle too cuz that will give you more or less wheel flop.
Re: do heavier wheels make bike less twitchy? [pacific]
[ In reply to ]
pacific wrote:
All other things being equal (same bike, same rim depth), would the increased gyroscopic effect of a heavier front rim make a bike more stable and less twitchy feeling when riding on the aero bars?narrower tires will make it less twitchy too.
Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter
Re: do heavier wheels make bike less twitchy? [jackmott]
[ In reply to ]
jackmott wrote:
pacific wrote:
All other things being equal (same bike, same rim depth), would the increased gyroscopic effect of a heavier front rim make a bike more stable and less twitchy feeling when riding on the aero bars?narrower tires will make it less twitchy too.
Really? Just front or front and rear?
Re: do heavier wheels make bike less twitchy? [GreenPlease]
[ In reply to ]
probably only the front matters.
longer contact patch
more resistant to turning
lower tire pressure should make it less twitchy too, all else equal
generally though, if you are having 'twitchy problems' you need to look at your fit/bike geometry or practice more.
You shouldn't need special wheels or narrow tires to make the bike behave well.
Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter
longer contact patch
more resistant to turning
lower tire pressure should make it less twitchy too, all else equal
generally though, if you are having 'twitchy problems' you need to look at your fit/bike geometry or practice more.
You shouldn't need special wheels or narrow tires to make the bike behave well.
Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter
Re: do heavier wheels make bike less twitchy? [damon_rinard]
[ In reply to ]
damon_rinard wrote:
Yes. But not primarily because of increased rotational momentum about the hub axle or precession, as some might tell you. It's simply because a heavier rim+tire (rolling or not) increases the moment of inertia about the steering axis. This is noticeable when the rim+tire weight difference is medium-large. Around 100 grams is enough for most folks to feel it.
That said, I don't know anyone who adds weight to gain stability. We all want negative weight bikes. ;-)
Cheers,
That is really interesting, I had never thought about it that way before. If I understand what you're saying correctly, then you could get the same effect by adding massive weight to the end of the aero bars on a tri-bike? What if you put like 5 lbs of lead tape by the bar shifters, would that lend enough stability to use a disc wheel in the back at Kona (only half kidding here).
Re: do heavier wheels make bike less twitchy? [sjcby]
[ In reply to ]
Or a handlebar bag! But it gets weird maneuvering through traffic at low speeds. I wonder if that's why my commuter is easier to ride with no hands.
/kj
http://kjmcawesome.tumblr.com/
/kj
http://kjmcawesome.tumblr.com/