frame for pursuit and TT, tri?

On Jan 17, 6:45*pm, "
wrote:
On Jan 17, 12:34*pm, Dan O wrote:



On Jan 17, 10:18 am, Phil H wrote:

On Jan 12, 10:54 am, "Mike Jacoubowsky"
wrote:

"mtb Dad" wrote in message

...

Anyone heard of an all purpose frame that can be used for both TT and
pursuit? *I guess it would have track dropouts with a derailleur
hanger, and an adjustbale bb (Phil?) to get track and road chain
lines. *Seems like a better investment for the occasional competitor,
and for loaning out to juniors, rather than specialty bikes for each.

That's a *lot* of work, converting a bike back & forth like that. But if
you really wanted to do it, you just buy a track bike and have a
derailleur hanger brazed onto the dropout. Not difficult to do at all.
The chainline is a non-issue; moving the chainring from inside to
outside will move your chainline quite a bit. You're going to have
another issue though; track bikes, pursuit and otherwise, are 120mm wide
at the rear. Road bikes are 130mm. You could change out the axle in the
track wheel and re-space it to 130mm, and re-space the the rear end, but
10mm is a *lot* with a modern, stiff rear triangle.

I'm thinking it makes more sense to pick up a used track bike for
pursuit, and adapt a conventional road bike for TT work. The pursuit and
TT bikes have less in common than you may have thought.

--Mike-- * * Chain Reaction Bicycleswww.ChainReactionBicycles.com

I thought about keeping 120 spacing and using a 5speed freewheel for
TT mode. I have a disc wheel where I could do that but my pursuit
frame doesn't have a suitable rear brake attachment.

Excuse my ignorance WRT time-trial (?) an pursuit racing, but what's
the rear brake for?- Hide quoted text -

- Show quoted text -

In the USA all sanctioned races (non-track) require two brakes. *Don't
know how meticulous the officials are about checking equipment. *But
technically you have to have two working brakes.

If that is all that is technically required, show them both feet.

On Jan 17, 10:23*pm, una farrar wrote:
Zipp wrote back and says conversion kits only come in 120 mm only for
track. *

But, found this option for converting (some) shimano hubs to fixed,
assuming the disc I find has shimano guts (do they make any?).http://surlybikes.com/parts/fixxer/*It also mentions different
spacings, so I'm thinking I could set it up to match the chain line of
the outer chain ring, and avoid having to mess with cranks and bb's.
"Most converted hubs can be spaced 120, 126, 130 or 135mm."

Can't quite grasp the math of chain line tho; does the diagram herehttp://surlybikes.com/uploads/downloads/Fixxer.pdf, suggest I could
get a big ring chain line and have the rim properly centered on the
locknuts?

If that worked, the conversion steps might be, remove the chain,
derailleurs, brakes, cables and bars, the axle and freehub of the rear
hub, bottle cages.

Add track aero bars, add fixxer axle, add a shorter chain. *For aero-
geek points, tape the cable ports. Maybe take off the inner ring and
use track chain ring bolts.

Assumes the cranks ok the same length, tt/tri bb height is ok on the
track.

Any other flaws in my thinking?

Sorry that was me. My daughter was signed in on this computer.

On Jan 18, 6:23*am, una farrar wrote:
Zipp wrote back and says conversion kits only come in 120 mm only for
track. *

But, found this option for converting (some) shimano hubs to fixed,
assuming the disc I find has shimano guts (do they make any?).http://surlybikes.com/parts/fixxer/*It also mentions different
spacings, so I'm thinking I could set it up to match the chain line of
the outer chain ring, and avoid having to mess with cranks and bb's.
"Most converted hubs can be spaced 120, 126, 130 or 135mm."

Can't quite grasp the math of chain line tho; does the diagram herehttp://surlybikes.com/uploads/downloads/Fixxer.pdf, suggest I could
get a big ring chain line and have the rim properly centered on the
locknuts?

If that worked, the conversion steps might be, remove the chain,
derailleurs, brakes, cables and bars, the axle and freehub of the rear
hub, bottle cages.

Add track aero bars, add fixxer axle, add a shorter chain. *For aero-
geek points, tape the cable ports. Maybe take off the inner ring and
use track chain ring bolts.

Assumes the cranks ok the same length, tt/tri bb height is ok on the
track.

Any other flaws in my thinking?

Your converted hub wont be track legal. I think its far better to get
an economical track bike. Fit a front brake for road use and leave it
at that.