jonathanf2

I'm currently running 700c wheels, but I'm entertaining the idea of going 650b. I'm wondering besides the other benefits of better grip and perhaps lower gearing, will going with the smaller diameter wheels help on climbing, mainly loose dirt/gravel trails? Most the articles I read don't really delve into the climbing aspect of 650b, mainly just the comfort benefits. I'd be interested in hearing how 650b fares for climbing. Thanks!

Badger6

The only difference I can discern is that they seem to "spin up" faster. Climbing performance "feels" the same to me.

jonathanf2

So the smaller diameter wheel, offset with the wider/taller tires probably wouldn't gain much for climbing then? Is the effects on gearing (being lower) minimal as well?

Badger6

I'm only going off of feel. I have never done a controlled test, I just know that for me when I've got my 650b set on (with 2.1") they don't feel noticeably different. As for gearing, I tend to pick the gear that lets me spin the cadence I want to spin, I don't really over analyze it much while riding. But, I generally am using the same gears regardless of the wheelset, though a true comparison is tough, since I use the 650b set on rides that I know will be over rougher terrain and would benefit from the wider rubber and use the 700c on rides that stick to "smoother" tracks.

But, you got me thinking...I just plugged in my two wheel sets, 700c shod with 38mm, and 650b shod with 2.1", 46t chainring and 10-42 cassette, in a gear calculator. The gearing is almost identical, to the point that the difference is indistinguishable. What that tells me is if you are going to go to 650b and want to use that to get lower gearing, you need to use narrow tires...which defeats the purpose of 650b, IMO.

tangerineowl

Doing fairly long climbs up steeper grades with loose surface I do prefer the extra cush of a wider 650b.
For me, there's only about one tooth jump between 700c and 650b. 700c being on the larger cassette cog.

A narrow 700c with deeper knobs can match the climbing grip of the 650b with lower knobs, but it is a harsher ride.

Makes a difference also when you're running 1200gm wheels and one of the lighter 2.1/2.2 options.

Russ Roth

All things being equal the 650b should climb better. So same make model and width of tire, same hubs, same make, model of rim, same cassette and built with the same spokes the 650b should climb better. It would have a lower diameter which would be easier to turn up a hill and the parts would all be lighter by some amount. Often 10-30g per rim, 5-8 grams in the spokes combined, and 20-100g in the tires depending on quality and size, so potentially a good weight difference though can be small enough to not be noticeable as well.
If you're going smaller to go wider, then maybe. Tire tread and weight will make a difference.

Badger6

All things aren't equal, though...

For instance, my 700c wheelset is rolling on Pathfinder Pro (38mm), and the tire weight is generally around 490g. My 650b wheelset wearing 2.1" (ERTRO is 52-584) Vittoria Barzos which each weigh in around 670g! Despite the weight saving on the smaller rim and slightly shorter spokes, the wheelset is only about 70g lighter on both ends, while the tires are in total 360g heavier. Certainly, my tire choice contributes to this, but I don't have a 650b wheelset to save weight, I have it for the comfort it provides on the rougher trails I ride.

Rolla

Outfitted with the same chainring and cogs, a 650B wheel will give you lower gears than a 700c wheel by a couple of gear inches. Whether this is "minimal" is subjective.

jonathanf2

Thanks for all comments so far. I'll probably stick with 700c wheels for now. I always road ride before hitting the trails and I think I'll be better served sticking to that size. It seems the tire weight of 650b will negate its advantages for climbing from what I'm gathering from the various posts here.

ThermionicScott 

Without some combination of lighter rotating weight, faster tires, or lower gearing, there's no benefit to 650B for climbing. That's why you're not seeing a lot of articles claiming it. The engine is the most important thing right now for you.

Fentuz

I was looking at gearinch for 700-38 vs 650-50 and it seems the gearinch difference would be the equivalent of 1.25T on the chainring so if you were to swap from a 40T chainring to a 39T, you 'd get a similar effect.

Now, Badger6 comment about "spinning up" faster. That is interesting as I noticed the same and thought it was down to better rolling resistance of the tyres i have on the 650b.
Now, you could argue the "heavier" outter of the 650B will require more torque to change rpm drastically but will store more energy like so should keep spinning at a given rpm range better like a flywheel.
Not sure if it is really noticeable. (I think DT swiss published something about than).

Badger6

Like I said, it's all based on feel, no actual measurements or compared (comparable) data...could just be placebo. In reality, the tread on my 650b set would likely measure a whole lot more rolling resistance than that on the 700c. So, there is that also...

jonathanf2

Would going with carbon wheels be another option if I want to improve my trail climbing? My 2nd bike has a carbon frame, wheels, lightweight cassette + Shimano 105 groupset and the performance difference between the two bikes is very noticeable when road climbing. My alloy gravel bike though rides in much rougher off-road conditions, so I've been hesitant going carbon with the wheelset since the trail descents are usually littered with small drops, rocks, twigs and tree roots. Though climbing feels much more heavier when trying to ride up the trail. That's why I was considering 650b, but maybe reducing wheel weight might be a better option for me.

Badger6

I’ve said it many times: climbing better is a function of the motor first. Every thing else helps, a little. Carbon hoops will all around be a nicer ride, but the few hundred grams saved won’t all of a sudden make you fly up hills. Honestly the weight loss on a bike that makes the biggest difference climbing is the rider themselves.

Rolla

Personally, I'd go with durability over weight savings.

A reduction in rotating weight will improve efficiency, but I think weight is often over-emphasized as a means of improving performance all by itself. For me, following Ned Overend's simple advice made the biggest difference. He said, "Just convince yourself that you love to climb."

ThermionicScott 

Big +1 to this. It's a virtuous cycle, once you decide that you enjoy climbing, you'll put more into it and get way better at it. You can't buy your way to being a better climber.

ClydeClydeson

Virtually no difference. If tires are chosen to make the overall diameter the same (choose 650b tires approx. 19mm wider than the 700C tires your comparing), and weight is the same, there will be virtually no difference besides maybe a bit smother ride and maybe better traction on wider and softer 650bs.

And contrary to a common misconception, added weight on your wheels only effects climbing the same amount as having the same extra weight added to a static part of the bike, like in your water bottle.

Rolla

Lennard Zinn puts it this way:

"There is no question that if a rider climbs at constant speed, it doesn’t matter where the weight is located on the bike. Extra mass could be concentrated on the pedals, at the rims, in the frame, or in the hubs, and as long as the bike’s total weight is the same and it has otherwise the same characteristics, it will create the same resistance to the rider’s efforts.

That said, there is also no question that it takes more energy to accelerate the same amount of mass if it is located out on the rim as if it is located at the center of the wheel (or on the frame)."

Badger6

As told to me many years ago, if you want to go uphill faster, go up hills a lot.

Badger6

Sorry about the second post, but also…

What if you could have both? A properly laid up carbon rim will be stronger and lighter than even the best aluminum wheel. Now, that said, the ‘stronger’ part won’t come into play, likely, until the average rider has ridden way past their own abilities. So…for the average sport rider the choice between carbon or Aluminium is usually a matter of weight and cost.

Rolla

Sure, I guess. In the OP's case, however, I think buying off-road worthy carbon wheels is a hundred dollar solution to a ten cent problem.

Badger6

Oh, definitely without a doubt.

As I stated, for the regular sport rider (I am squarely in this group at this point), it is a matter of weight and cost. The latter factor being the one that keeps most people from ever got in down the road of carbon hoops.

Wet Coast Rider

It sounds like you want to try 650b. Any real difference will be in 'feel' and not performance (ignoring placebo effects) so either take the plunge and buy them or try to find a friend with a set you can borrow.

And a few people have said already, maybe some hypnotherapy to convince yourself that you really like climbing would be the most effective route to take.

Rolla

Yep -- I'm in that same group, as I believe 90% of riders probably are. And while there's nothing wrong with buying lightweight gear, it's not only about the expense; my performance just isn't good enough to where a few hundred grams is going to make any difference.

Calsun

Climbing is helped by shorter chain stays and a more upright position and wider tires. Going to tubeless tires is also an option. Check the specs for the varous bikes from Specialized and Trex and notice the difference in chain stay length and seat tube angle based on the intended use.