Frame design questions

You are describing my signiture bike. In 26" 71 head angle gives that relaxed ride. In 700c, 72.5
nets a similar feel. The caveat is forks. Kinesis and others make a fine 26" fork. For 700c,
cyclocross forks work, but while I spec 47mm offset, things can vary a lot. Axle to crown on cross
forks varies from 380 to 410mm. I use 43cm chainstays on both. My guess is in bump comfort, tires
2/3 frame, 1/3, but the frame is near totally responsible for that relaxed handling feel. Tom

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410.426.3420 trent gregory hill <[email hidden]> wrote in message
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Quoted message said:

I'm in the market for a custom bike for randonneuring and fast-ish rides and would like for it to
have fit and ride characteristics similar to my touring bike, which, for all its many and manifold
virtues, is a pig at ~31 lbs. The fit should be fairly easy to clone, but the ride qualities are
probably going to be more elusive. The bike to be cloned, a Thorn Nomad 595S, has a long wheelbase
(108.4 cm), long chainstays, a slack headtube, and lots of trail. It's designed around 26" MTB
wheels: the tires I use (which Thorn recommends) are Panaracer Hi-Road 26x1.5".

The combination of the long wheelbase, relaxed steering, and fat tires makes for a really stable
and comfortable bike that you can ride all day and, I suspect, all night, as long as you stay
awake. It floats over bumps, laughs at chipseal, and in general does everything that a touring
bike should do.

So here's my question: How much of the bike's ride characteristics stems from the geometry and how
much from the fat tires? Could I duplicate the quality of the ride on a 700c wheeled bike? I ask
because, if I get the bike built around 700c parts, I can just switch parts from my current 700c
bike (that's too small for me) to the new one.

Thanks, Trent

trent gregory hill said:

I'm in the market for a custom bike for randonneuring and fast-ish rides and would like for it to
have fit and ride characteristics similar to my touring bike, which, for all its many and manifold
virtues, is a pig at ~31 lbs. The fit should be fairly easy to clone, but the ride qualities are
probably going to be more elusive. The bike to be cloned, a Thorn Nomad 595S, has a long wheelbase
(108.4 cm), long chainstays, a slack headtube, and lots of trail. It's designed around 26" MTB
wheels: the tires I use (which Thorn recommends) are Panaracer Hi-Road 26x1.5".

The combination of the long wheelbase, relaxed steering, and fat tires makes for a really stable
and comfortable bike that you can ride all day and, I suspect, all night, as long as you stay
awake. It floats over bumps, laughs at chipseal, and in general does everything that a touring
bike should do.

So here's my question: How much of the bike's ride characteristics stems from the geometry and how
much from the fat tires? Could I duplicate the quality of the ride on a 700c wheeled bike? I ask
because, if I get the bike built around 700c parts, I can just switch parts from my current 700c
bike (that's too small for me) to the new one.

My Nomad (545 - not sure what top tube length I specified, but it was based on another bike I had)
handles like a supertanker in treacle, although it is undeniably strong and has all the right
braze-ons! I really don't think you want to copy the geometry, because it's designed to cope with
heavy loads and therefore its unladen handling, particularly the floppy steering, is compromised.
Also, remember that the main reason for the Nomad's long chainstays is pannier/heel clearance and
any difference it makes to the ride is coincidental.

700c will give you a much better choice of fast road tyres so I'd go that way. Most audax bikes have
slightly stretched racing geometry. There's nothing wrong with this - after randonneurs, the people
who do the largest daily distances are the racers, after all.

Some manufacturers will allow you to rent their bikes before buying for a modest fee - why
not try that?