43mm vs 45mm rake for Soma Smoothie?
Just ordered a 58cm Smoothie and I'm looking to pair with a Ritchey Carbon fork that I already have, a 45mm rake
Soma's websites recommends a 43mm fork... In an email their rep said a "45mm rake should be no problem. It will handle a little quicker than a 43mm rake."
Can someone help me understand what this means? I hate laggy steering, but then again I don't want something twitchy. Will 2mm make the difference?
I was in the same boat looking for a new fork for my Litespeed. I wanted to get a Wound Up, but they only come in 40 and 45 --- I need a 43. Seriously, how much difference can 2-3 mm make? I can't tell the difference between 172.5 and 175 cranks. The fit guy at my LBS said it can make a lot of difference. I concluded that I had better buy a fork that has the rake the manufacturer recommends.
I run a 54 Smoothie with a 45 fork and all is good. It handles quite well.
Cycling should be fun. The rules are stupid. Ride because you love to ride. --QED
Fork rake tells only part of the story. You really want to calculate trail for an idea of how the bike will handle - at least 'on paper'.
For example, assuming the same axle to crown fork measurements, the 58cm Smoothie has a HTA of 73.5 degrees. with a 43mm fork rake and running 23c tires, trail is 55mm's - about right for this type of bike. Changing fork rake to 45mm's and keeping with 23c tires, trail changes to 53mm's, which is on the quick side. Whether you find it "too" quick will depend on your handling preferences.
If you want to go with the 45mm fork, consider going with 25c tires, which will split the difference in trail (54mm's).
Personally, I'd try the 45mm fork. Seeing as you're looking at a race (as opposed to a relaxed geo) bike, I doubt you'll find the handling objectionable.
A 58cm Smoothie has a 73.5 degree head angle.
The e-mail from the Soma rep is right but perhaps he used the wrong terms. More fork rake will make the bike feel as if it "steers" faster or need more attention from the rider to hold a straight line. A bike with less fork rake will hold a straight line more easily without rider input.
2mm is not much of a difference in your case and unless you could do a side by side comparison, you quite likely wouldn't notice the difference. It will be no harm done to at least try the Ritchey fork. At the absolute worst, if you needed to satisfy your curiosity, you could buy a used fork on eBay to see if you would prefer it.
I personally would pair a 73.5 degree head angle with a 40mm raked fork. I've ridden 73.5 degree head angle bikes before and the head angle alone already makes the bike feel twitchy to me. Installing a 40mm raked fork would calm things down.
From personal experience, I will tell you that a 5mm change in fork rake is considerable as to how it changes the behavior of the bike. I wouldn't bother trying any change less than that.
I went from a 44mm rake to 50mm with a HT angle of 72.5 degrees. My trail went from about 61mm to a 55mm. I like the bike as it is now, but I really did not see a huge difference in handling. I feel most people exagerate small changes in fork rake and the affect on handling. Experts (Tom Kellog) feel that a mid 50's mm is a good trail. Good site to determine trail:
Bicycle Trail Calculator | yojimg.net
Lots of stuff to consider, try your current fork and if you don't like it switch. Good luck
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