jslipscomb
New Member
CUSTOM-LENGTH CHAINSTAY EXTENSION FOR BEST VISIBILITY - SILVIO
Problem: Too high, too low. Two photos below show that at my height with no chainstay extension the end of the steering tube blocked my low forward view of a potential hazard, but with a 100 mm chainstay extension the handlebars likewise blocked my view. Blocked either way.
Solution: Just right (between too high and too low). Photo below shows that with a 40 mm custom-length chainstay extension I look straight down the tube for best visibility, seeing the potential hazard.
A local machine shop took the Silvio 100 mm chainstay extension and copied it shorter, in solid aluminum. Local machine shops are very expert and can do anything, for a price.
I settled on 40 mm by sitting in the bike and tilting the steering tube to the optimum angle for me, while a helper made the 40 mm measurement. Considering the high price of this job, that helper must be someone technically-inclined, who really does understand how to correctly measure the gap.
Photos below: Silver copy, aluminum 40 mm custom chainstay extension. Black original 100 mm chainstay extension from Cruzbike.
Experience:
My mistake: I should have specified an exact copy, save but for length. The machine shop first copied the part exactly, but then when they found the fit to be tight, imagining that I might be unhappy, they got creative and thinned-down the new part, so it would slide on and off easily. Wrong. The chainstay extension fit should be tight to ensure a rigid drive train that delivers power to the road, instead of power, dissipated as heat, to flexing the connections between parts. Lack of rigidity had to be overcome by tightening the 4 chainstay extension bolts very tightly.
Specifying aluminum was one thing I did right. Another part I had made by a machine shop got made in heavy, rusting steel, because I failed to specify aluminum. Machinists do not necessarily know that bicycle = aluminum.
Parts:
$95.00 Chainstay Extension for Silvio, 100 mm long from Cruzbike, too long for my height.
$460.00 Chainstay Extension 40 mm long by Fenbar, a local machine shop. Copy of the 100 mm chainstay extension but shorter.
Problem: Too high, too low. Two photos below show that at my height with no chainstay extension the end of the steering tube blocked my low forward view of a potential hazard, but with a 100 mm chainstay extension the handlebars likewise blocked my view. Blocked either way.
Solution: Just right (between too high and too low). Photo below shows that with a 40 mm custom-length chainstay extension I look straight down the tube for best visibility, seeing the potential hazard.
A local machine shop took the Silvio 100 mm chainstay extension and copied it shorter, in solid aluminum. Local machine shops are very expert and can do anything, for a price.
I settled on 40 mm by sitting in the bike and tilting the steering tube to the optimum angle for me, while a helper made the 40 mm measurement. Considering the high price of this job, that helper must be someone technically-inclined, who really does understand how to correctly measure the gap.
Photos below: Silver copy, aluminum 40 mm custom chainstay extension. Black original 100 mm chainstay extension from Cruzbike.
Experience:
My mistake: I should have specified an exact copy, save but for length. The machine shop first copied the part exactly, but then when they found the fit to be tight, imagining that I might be unhappy, they got creative and thinned-down the new part, so it would slide on and off easily. Wrong. The chainstay extension fit should be tight to ensure a rigid drive train that delivers power to the road, instead of power, dissipated as heat, to flexing the connections between parts. Lack of rigidity had to be overcome by tightening the 4 chainstay extension bolts very tightly.
Specifying aluminum was one thing I did right. Another part I had made by a machine shop got made in heavy, rusting steel, because I failed to specify aluminum. Machinists do not necessarily know that bicycle = aluminum.
Parts:
$95.00 Chainstay Extension for Silvio, 100 mm long from Cruzbike, too long for my height.
$460.00 Chainstay Extension 40 mm long by Fenbar, a local machine shop. Copy of the 100 mm chainstay extension but shorter.
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