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Gibby

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Posts: 8
Reply with quote  #1 
My CoMotion Klatch has 700x38 wheels. What would I gain by switching to a 650b wheelset? Better ride? Lighter weight?
I am happy with my Rolf Hyalite wheelset, but wondering about 650.
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AlanEsh

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Reply with quote  #2 
You'll have a softer ride with larger tires, that's the main effect of going 650b.

Supposedly the smaller wheels will be more stable laterally (less flex). I don't see that as an important factor unless you're riding very hard on rough terrain, or your bike is loaded.

Without knowing what rims and tires you'll pick, weight is an unknown. Generally though, your 650b tires will be heavier and your rims will be wider so you probably won't save any weight on the rims.
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Noonievut

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Reply with quote  #3 
I think it depends on the type of riding you do.  38mm would be a great width for mixed surface, where the gravel/dirt isn't too technical (skill depending), and the surfaces are not full of potholes.

If you venture to chunky gravel roads, with thick washed out sections, or any sort of mountain bike trails with rocks and roots, the 650b will allow for a wider tire (frame/geo depending) and thus more cushion, more contact patch with the ground; more of a do-it-all tire (if 47mm+).

If you don't notice something missing from your current set-up, or if you're happy with the riding and have no complaints, maybe you're not missing anything at all.
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pushstart

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Reply with quote  #4 

One other point worth considering is BB height.

A 650B rim with a 47mm tire will be ~10mm lower to the ground (or more, depending on pressure/sidewall drop)  than the 700x38 you're using now.  That's a pretty big difference, so you probably want to consider that against the BB drop for your frame, etc.

I run 700x38 on my gravel bike with 78mm of BB drop, which feels great to me.  I ran a 650B 47mm setup briefly, but while I enjoyed the extra volume, the wheels felt smaller / bike felt lower than I like.  So I sold the wheels+tires after a couple of rides.

(OTOH, I've run 700x44mm tires which feel a little big.  700x38 seems like the sweet spot for my frame.)

 

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GHC

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Reply with quote  #5 
Another consideration is comparing wheel diameter.   A smaller wheel diameter will lower gearing, maybe slightly, maybe more .... depending on tire sizes you are comparing and what pressures you are running them.  "Cheap" way to lower gearing a little if that plays into what you want with other considerations.
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pushstart

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Reply with quote  #6 
That is true, though an even cheaper way to get the same 650bx47mm wheel diameter would be to put some 28mm tires on the 700c rims.  (Granted, it wouldn't really be as gravel-ready if you did that!)  But maybe this would be a way to experiment with ride height and gearing before committing to the 650b.
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chas

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Reply with quote  #7 
Yeah, but I find 28 mm tires make the bike handle a lot different.  makes it feel a lot like a road bike, where 2.1" tires make my bike feel like a mountain bike.  Its amazing how just changing tires (although at extremes) can make more difference than I would expect from geometry changes!
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HollyBoni

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Reply with quote  #8 
Quote:
Originally Posted by chas
Yeah, but I find 28 mm tires make the bike handle a lot different.  makes it feel a lot like a road bike, where 2.1" tires make my bike feel like a mountain bike.  Its amazing how just changing tires (although at extremes) can make more difference than I would expect from geometry changes!


Even when switching from 32s to 43s my experience has been the same. Other than the added comfort with the bigger tyres the steering feels a lot slower and the bike feels a lot more stable and calm overall. 
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