Soma Smoothie: Steel road frame build & review, pt.2

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The frame was delivered a few days later. I am VERY impressed with the finish of the bike and the quality of appearance. the joints and welds look wonderful. It’s a great loking bike and the frame feels light. LIGHT! I do know it’s four pounds, yet, it doesn’t feel that way. The other parts are on the way. There was much head scratching to choose those parts because I had a problem. If I wanted to run tires nearly 31mm in real size, It’s constantly recommended I use long reach brakes to get around their fatness, and that means I ned a long reach fork.

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Long reach forks are used for fitting larger tires AND fenders. Good stuff for the daily commuter or long range randounner. Out of my curiosity, one of the first things I did was try to see how much tire wouuld fit on this thing. I grabbed one of my cyclocross wheels and I’ll be darned if it didn’t fit.

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Here was a road race frame with about the maximum size tire anyone should run on it, something that probably measures 33mm. This bike could even run some gravel grinder races if it’s not too cruddy out there.

 

but for the cyclist craving the low rolling resistance of the fatter tire and the fast bump absorption all within a fast road machine, it adds to the problem. The long reach fork’s difference from standard. They are 10mm longer or more over a traditional fork. The result raises the front of the bike higher than designed and that action tilts the head and seat tube angles back farther. So my 72.5-degree head tube, raised by 12mm of extra fork, suddenly becomes a 71.5-degree tube and that changes the handling, as well as forcing my saddle more forward in adjustment to maintain the rider’s position. I may now not have the range of saddle adjusting because I’m already using zero setback seat posts due to some kinda short hamstrings.

Long story short, I couldn’t find any reliable information on what tire actual measure would fit in what normal fork. I had to get that long reach fork but it’s inherent issue to total geometry had me worried. I decided to find a measurement of both the fork axle-crown distance plus the bottom headset cup height for a total length. The lowest combination would win.

 

On a typical fast road geometry bike, 12mm of extra fork length would change the frame angles by nearly a degree. That’s not very noticeable until the bike is really driven hard and the most possible is asked form it. For example, downhill switchback turns, maneuvering in a tight and fast group ride, or desired general sensitivity. This is a race geometry frame after all. It was designed to an angle for a specific handling feel for a  reason so it would be a good idea to maintain that as much as possible.

I made a list of long reach fork lengths and lower headset cup heights. I now know that under the head tube of an external headset bike, the lower cup stack height for Ritchey is 14+mm, Chris King: 13mm, Cane Creek: 12.6, Interloc Racing (IRD): 11.3, and one other Italian parts maker has one in the 8’s but it’s twice as much as the rest and very boutique, as in, where do I get replacement bearings? So it was useless to buy that one. The forks all had ranges of length and they varied quite a bit.

The shortest long reach fork I could find is the Kinesis DC07 winter fork, at +6mm over what I have on hand and IRD has the shortest headset I could find at 11.3mm, for a total change of +5.8mm. Together that’s less than a half degree change, more like a third. That would be unnoticeable for all but the most sensitive professional racer. Mission achieved so the parts were ordered as well.

The Kinesis DC07 fork at 550 grams and, with a discount coupon, $135!

The Tange Technoglide headset, 110 grams and $72.

Frame, headset, fork together should weigh all up to around 2500g, or 5.56 pounds. We will see when it all arrives. I’m looking good for coming in under twenty pounds.

Next items to sell for build capitol: Ritchey basic fork and headset, Specialized carbon setback and Thomson aluminum setback posts.

Part 3 coming up when I get the headset, fork and bottom bracket installed professionally. Probably a real time week or so from today.

 

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