sweetspot

I have Jamis Renegade Exploit bike. A great bike but for the kind of riding I am doing (a lot of light singletrack) the standard 35 mm Clement Xplor tire gives too little damping to offer a comfortable ride.
Fortunately my bike offers a big tire clearance to get either 43mm 700c tire or 48mm 650b tire. Both would be Panaracer gravelking. So there is my dilemma: which will be better for overall ride quality. Will another 5 mm of tire width make a difference and will be worth changing the wheelset completely? I have calculated that 650b wheels with 48mm tire will lower the bb height from 274mm to 267mm which will be very similar to what new Specialized Diverge has and some early people rewievs suggest that this is too little and may result in pedal strikes. This could be even worse when the tires will be inflated to 30 psi to give me more comfort (another copuple of mm lower in terms of bb height). So maybe 700c 43mm will be enough and with similar tire pressure the bb height will be very similar to what I have today (so I won't mess with the bike geometry at all).

What are Your suggestion? What would You do?

fietsbob

N+1 time... now the 650B has become 27,5" in the Mountain bike world, 700C is 29er..

Spoonrobot 

What kind of single track?

I think you would be a lot happier on the 650bx48 than the 700cx43 - this coming from someone who rides a lot of single track on 700cx42 and 700cx50 - the latter is so much better for anything more than mild, smooth, dirt single-track.

267 is pretty low but should be workable if depending on your terrain. What length cranks are you using?

Marcus_Ti

My suggestion? You have a bike and wheels now. Tires are cheaper than wheels. So try the 700C GKs. NOTE, on my Pacenti SL25 rims-the 700x40 GKs measure 44mm IRL when inflated. YMMV depending on your wheels.

If you don't like how the bike handles, then you can worry about 650B wheels and tires....presuming ofc you don't already have a set of 650B wheels lying around.


With 700C versus 650B fat tires....the other issue is gearing. A 700x40C tire is a big tire, not just in width but diameter. So stepping up tire size will increase gear development....which depending on your crank/cassette may cause problems if you live somewhere with climbs. Also a 700x40+ tire is a heavy tire, all else equal-so acceleration will be more work.

tyrion

I don't see the point unless you find the dirt/gravel so soft you could use the extra bit of floatation.

sweetspot

the cranks length = 172,5 mm and by singletrack I mean a lot of rocks smaller and sometimes bigger ones and many, many roots so I truly understand the approach: the bigger tire the better. But this pedal strikes can be a real issue - to be honest even now from time to time I experience this so what it would be like with bb height at least 1 cm less?

Spoonrobot 

If you're having issues with pedal strike now probably best to stay with 700c sized wheels and just accept you're going to give up a little cushion over a wider tire. But body technique and the additional rollover can sorta make up for this.

sweetspot

Yes, I see Your point but to be honest my current wheels took so much beating already that it is hard to make them roll like new one (centering become an issue). This is the second reason why I am looking for a bigger tire.

And You right, bigger wheel will change the gearing but also it will make toe overlap problem bigger. By bigger I mean that I was in between in terms of frame size and I have chosen a smaller one so bigger tire will for sure make the problem worse. But smaller wheels can mess with the bike geometry too much which would be a pity because I feel that right now the bike geometry is spot on.

sweetspot

yes, after a few pedal strikes I already changed the technique so maybe I would get used to it. And maybe I will have to because there is other problem with bigger wheels - bigger toe overlap problem which I also have due to smaller bike frame that I have decided to buy

Marcus_Ti

How small is "smaller"? The smaller the frame the more 650B makes from a simple bike geometry standpoint.

sweetspot

I have frame 54 and I am 179 cm of height. I could get 56 but I wanted a smaller, more agile ride. Smaller 650B wheels will make 54 frame even more agile. Maybe even too agile when I will be riding downhill very fast.

tangerineowl

I'd agree with Marcus. The lowest cost to you at the moment is to try out the larger tires and go from there.

OneIsAllYouNeed

+1 on trying some 700x42ish tires. I recall feeling that my 'cross bike turned into a monster truck the first time I mounted some Panaracer Fire Cross 700x45 tires on it. I'd been using 32mm tires until then. My regular singletrack loops went from "challenging" to "fun". The handling will feel a little slower than your other tires, but that's not necessarily a bad thing.

650b x 48mm tires are cool if you plan to swap them regularly for a road wheelset with 700c x 30mm tires. It's an awful lot of expense for just trying wider tires, though.

unterhausen

going from 30mm to 38mm made a huge difference for me as far as a feeling of security. I would definitely try the 700c x 42mm first and see if you really want to change from there. I don't do a lot of singletrack, but some of our gravel roads are not much better, with football-sized rocks.

akwarfield

sweetspot

I went with Panaracer Gravelking 700c and for sure the comfort has increased but I still feel the need for better dampening especially in front (because front of the bike is most crucial in terms of riding comfort). So now I am considering two options: bigger 700c tire in front (because my fork will take something like 46 or even 48c) or going for redshift shockstop stem. Bigger tire solution is difficult because there is a very limited tire offerings in that sizes so in the end I can still end up with 650b wheels. So maybe shockstop will be better solution for me?

Oso Polar

Hmm, Renegade is rated for up to 700x42mm or 650x47mm tires, so I'm not really sure you can put even bigger 700c tire than you already have.
May be your tire pressure is too high? Or, may be, these trails are really just not suitable for a gravel bike and what you really need is an MTB - you are saying ride is way too harsh, wheels are bending, problems with pedal strikes?

trailangel

Buy a different bike.

vitaly66

Have you tried letting some air out of your tires? No need to run more than 50psi with those tires, ever. Off road, around 40 will do just fine.

sweetspot

I have tried ridding even with 30 psi but with pressure that low handling of the bike is compromised. I ride at 35-40 psi but like I said i still feel the need for better comfort. Shockstop stem looks like a nice solution but so is bigger tire in front. I know that jamis says that 42c is max but I see plenty of space around my front tire. Easilly for something like 47c. The back is a whole different story though but I am interested in front so it is no problem for me.

Metieval

In my Opinion....

Sell the Jamis buy a Giant TCX SLR cyclocross (high BB 60mm) and convert it to 650x47/48

I've ridden 75mm bb drop 700x40 on light singletrack and the BB height was a huge Negative!

I think the difference between a 700x40 and 650x47 is like 12-13 ish mm (radius)

so a 60mm BB drop converted to 650b would be around the equivalent (BB to ground) to a 73mm bb drop on 700x40

Honestly,,, all depends on your Singletrack and what is acceptable for a BB height for you. everybody has a different ride style.


Edit: nevermind my maths..... Riding Gravel says 20.1 mm difference on Diameter. so 10mm difference on radius. between a GK SK 700x40 vs 650x47 WTB Horizon.

https://ridinggravel.com/components/w...-650b-vs-700c/

Regardless, that puts a 60mm BB 10 mm closer to the ground after a conversion to 650b which is respectable for singletrack riding. in my opinion.

Noonievut

Abe_Froman

Personally, I think you should experiment a bit more with tire pressure. Going with a bigger tire is not going to make your ride any more comfortable. If your concern is damping/comfort...the only thing that really impacts that is tire pressure. The reason people run bigger tires is so they can lower their tire pressure without bottoming out/pinch flatting. You're not at your minimum pressure, so your adjustment really needs to be in pressure, not tire size. You can go much lower in pressure. I have a feeling you may just need to get comfortable with the feel of lower pressure (and the comfort of it). CX racers run <20psi on 33mm tires.

jp911

I like BOTH! Helpful, I know...

I have 700C and 650B wheels for my gravel bike and I've found that I like to alternate depending on what I'm doing. For longer rides where the surface is a little smoother you can't beat the 700C with 40-45mm tires...they just keep rolling and you can adjust the pressure if things get a little rougher. For tougher terrain, I love 650B with 47mm tires and lower pressures. The bike is comfier, there's more grip, and (for me) being a little lower actually gives me more confidence.

When I've tried the 2 wheelsets back-to-back on the same route I will say that the 650B wheels feel a little more sluggish. The weight between the 2 setups is pretty close, so it may be the tire pressure? Or maybe just the reduced circumference? Regardless, I still like both.

sweetspot

Thank you all for the replies.

Starting with the suggestion of changing the bike. I generally like a lot my Renegade Exploit. I rode many bikes before both MTB and Hybrid and Renegade is the closest thing to my need for sure. I love to have freedom while riding and enjoy both speed and versality to go almost anywhere. I need a do it all bike and I think that my Jamis is preety darn close to this definition.

I learned that swapping to 650b tires on my bike will be tough because of low bottom bracket and tire size limitation (max 48c). So in order to have more comfort from tires I would need to change the bike for something like Boombtrack hook ext or Open U.P. which can take up to 2,1 650b tire. For now I don't think I will do that in near future.

In terms of lowering pressure - my bike have ATD 470 rims with a very narrow internal width so it is difficult for me to go tubeless. But for sure I will once more experiment with lowering the tire pressure, but focusing on front tire. We will see where it will get me. Buying new 700c rims is a no go for me due to the fact that there is a very limited tire choice above 43c so I will gain little and spend a lot.

Finally there is a shockstop stem from redshift. I think that I will try it and see if it helps. For sure it can mitigate bigger hits but I am concerned that the constant road shutter will still go to my arms and neck because solutions like shockstep are simply too slow to deal with that. I believe that only double decker handle bar from Canyon Grail can offer a substantial improvement in terms of that. And to be honest, if this bike had even bigger tire clearance that I think I would buy it...