What to build a custom around: 650b 42, 48 or 700c 38?

[Daniel Jackson]

I'm 6'3" 180 lbs. The bike will be 8/5/8 all around. 63 x 60cm. Low trail. Purpose built for long day rides and randonneuring. Designed for 60% pavement, 40% dirt roads, variably hard pack to loose dirt with big fresh rock gravel when the grader decides to do some work that day. 

A typical ride looks something like this or this. 

If the route incorporates more dirt or class IV roads, then I'll turn to my Hunqapillar.

If the route requires more than a 25 lb. up front load, then i'll turn to my Hunqapillar.

If the route is off road singletrack, then I'll turn to my Jones. 

What tire should I build the frame for? BSP, SBH or BPs? I'd be happy with centerpulls or cantis.

Thanks much!

Daniel

[Kieran J]

Considering the other bikes you have and your intended tube spec, I would think 700x38 would be the way to go.

I'm 6'4" and following my brief foray into 650b, I didn't see the point of it for us taller riders. We don't face the constraint of tighter frame dimensions. 700c wheeled bikes with tire clearance up to 38-42mm preserve the ability to run a narrower tire for smooth pavement, or a slightly cushier one for choppy stuff.

Have you had much experience with 650b? You may have different thoughts on it than I do.

KJ

[Mark Guglielmana]

+1 At your size, if you're building a new frame, you can make it fit 700 x whatever. Or 650b x whatever. If you're riding 60-40 road-dirt, you're spending more time in the dirt. 38's will work, 42's would be better, but for dirt riding, 48's are better still. At Jan's un-meeting, I could keep up as long as the ground was packed and not too rutty on my 42 Hetres, but once we got in the loose and weathered roads, the fatter tires were hard to keep up with. I rode with 3 other guys the next day, same story - the one fellow with an NFE with Compass Switchback Hills just floated over ruts, gravel, and junk. If your roads aren't loose and/or very rutty, 48's are probably overkill.

My recommendation: pick the tire you want to ride, and build the bike around that. You know your roads better than anyone else.

[Brad]

Hey, you almost went by my Aunt's house in Jay, but her road dead ends after it turns to dirt before it gets to Canada.   38's or 42's should work.  The issue I would look at is soil type.  I am guessing your not dealing with much loose sand, just selectman who don't see a reason for paving.  If you do the math the circumference of a 650B x 42 is pretty much the same as a 700 x 23.   I would start looking for a pair of Mafac Raids now, unless you are going to commit to brazed on breaks.   Experience from the conversion world suggests that it is very possible to have a bike that can handle both 650B and 700C wheel sizes with a simple change of brakes.   With centerpulls it might be possible to make that change without changing a whole lot other than the brake mechanism. 

On Monday, May 16, 2016 at 9:56:49 PM UTC-4, Daniel Jackson wrote:

[Harald Kliems]

On Monday, May 16, 2016 at 9:24:40 PM UTC-5, Kieran J wrote:

Considering the other bikes you have and your intended tube spec, I would think 700x38 would be the way to go.

I'm 6'4" and following my brief foray into 650b, I didn't see the point of it for us taller riders. We don't face the constraint of tighter frame dimensions. 700c wheeled bikes with tire clearance up to 38-42mm preserve the ability to run a narrower tire for smooth pavement, or a slightly cushier one for choppy stuff.

Why wouldn't you be able to also ride a narrower tire in 650B? And even if you're tall, you still have to make the tire fit at the chainstays, something that is easier to achieve (while maintaing low Q) with 650B. And of course a 650B wheel and tire will be lighter than 700C (and if you believe Jan's theory, rotational inertia will be optimal with 650Bx42 and equivalents).

Not saying that 650B is necessarily the better way to go, but some pro-650B arguments still hold true for taller riders.

 Harald (who is 6'5" and has both 700C and 650B bikes in his stable)

[Philip Kim]

I would go with 700x38 at your height. 700x38 Compass Tires would be awesome for what you are suggesting, and then you can go 700x32 for exclusive pavement.

That would make it less overlap. 

On Monday, May 16, 2016 at 9:56:49 PM UTC-4, Daniel Jackson wrote:

[Kieran J]

Some fair points, Harald. Naturally, YMMV.

Personally, given the range choice of 700x28-42 vs. 584x32-42 for the 63cm mainly-road bike the OP is looking for, it's an easy choice in my mind.

KJ

[Philip Kim]

Harald, true. 

Also to add, wouldn't toe overlap be less of an issue on 650b wheels as well? I, myself, am not a tall rider nor regularly experience toe overlap.

-Phil

On Tuesday, May 17, 2016 at 8:43:18 AM UTC-4, Harald Kliems wrote:

[Steve Palincsar]

TCO will always be less for a given width in 650B than 700C.

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[Kieran J]

My new 64cm BMC Monstercross is running 29x2.1 Schwalbe Thunder Burts with no TCO at all. It doesn't even have a high fork rake or a particularly long TT. Anything besides a tight geo track bike or a crappily designed one such as the Surly Cross Check shouldn't exhibit it.

KJ

[Steve Chan]

On Tue, May 17, 2016 at 5:43 AM, Harald Kliems <kli...@gmail.com> wrote:

Why wouldn't you be able to also ride a narrower tire in 650B?

   I think the selection of fast (and possibly faster) skinny tires is dramatically larger in 700c. I say that as a person who mostly rides a custom 650B, and currently has no bikes with 700c wheels.

And even if you're tall, you still have to make the tire fit at the chainstays, something that is easier to achieve (while maintaing low Q) with 650B.

   Are you sure? I would expect that the extra 19mm of radius for a 700c tire vs 650b tire of the same radius gives the builder more room for working the chainstays to fit low Q cranks.

And of course a 650B wheel and tire will be lighter than 700C (and if you believe Jan's theory, rotational inertia will be optimal with 650Bx42 and equivalents).

   There's definitely a difference in how easy it is to spin up the wheel - a 700x42 wheel is going to be more of a slog on something like an extended climb compared to a 650x42.

 

--

"Sow a thought, reap an action. Sow an action, reap a habit. Sow a habit, reap a character. Sow a character, reap a destiny." - Samuel Smiles

[Justin Hughes]

On this size frame I would go with 700c. Actually, I would go disc so that I could run 48-584 or 32-622.

[Steve Palincsar]

On 05/17/2016 12:01 PM, Justin Hughes wrote:
> On this size frame I would go with 700c. Actually, I would go disc so
> that I could run 48-584 or 32-622.
>

Other than an aesthetic issue of thinking 584 wheels might "look too
small," what factors related to frame size would make 622 superior to
584 "on this size frame"?

[Daniel]

I think Daniel asks an interesting question. I currently have my 62cm 700x38C bike for sale and think the tire/wheel combination is great. I've had (and still have) 650B bikes (currently a '71 Raleigh International conversion and my wife's GT Tachyon) and am building a 26" Rat Trap Pass bike at present, so I've done some experimenting--nowhere near the level BQ has--enough to strongly endorse 700x38C. I know that Rob @ Ocean Air Cycles feels the same--his bikes change wheelsize from 650B to 700C @ 59cm and above. (I had an interesting conversation with him once in which he recommended 38mm over 42mm in 650B due to the profile of the tire on a 23mm-ish outer width rim in which he likened the 42mm to being more like a lighbulb and feeling less stable.) Some Rivendells also scale to large wheels on bigger frames.

I'm very happy on 700x38C but it does feel more "stable" than 650x42B meaning not as quick handling but by no means is this on the magnitude of Porsche 911 vs family van.  700x38C is nice and plus, but 650x42B has more air volume (11.6L vs 10L, if the math's right) so for better and for worse, 650x42B is more pillowy.

So in conclusion, I dig the 700x38C--it's wonderful on the pavement, gravel and hardpack that I've ridden.

Tire size aside, are there any factors pertaining to frame stiffness? All things the same on a bike frame like this, I think the fork will be short on the 650B bike, but the HT will be longer. I don't have any answers...just wondering what (if anything) the group thinks might happen to frame flexibility/stiffness of 2 frames of the same (large) size with the same tubing, but designed for these two different wheel/tire sizes.

Daniel
PDX

[Justin Hughes]

There are many more varied rim and tire options for 622. That's not really an argument against 584 as much as it is an endorsement of 622. But, like I said, I would use disc brakes and have the best of both worlds. One could have a 584 set with SBHs and Thunder Burts and a 622 set with nice CX tires or go-fast 32s.

Justin

[olof...@gmail.com]

If you have a custom made it is absolutely possible to have the bike built with clearance for both 622/38 and 584/48. You could use a DiaCompe 750 brake för the smaller wheels and a „normal“ reach brake for the bigger ones. With fenders and a light good fork. Why not have the possibilty to play with both worlds?

 

Olof Stroh doing just that in

Uppsala Sweden

[Steve Palincsar]

On 05/17/2016 01:01 PM, Justin Hughes wrote:

There are many more varied rim and tire options for 622.

That may well be true; but why "on this size frame"?   And of those varied tire options, how many are genuinely comparable to the Grand Bois and Compass 650B tires?

[Alex Wetmore]

I don't know where to find tires comparable to the Compass 42-52mm tires in the 622mm rim size.  The largest Compass tire in 622mm is 38mm.  It's a really nice tire and I use them on my commuter bike (which probably gets my most miles right now), but they aren't as nice as the wider tires on dirt.

40% dirt, 60% pavement would make me select the Compass Switchback Hill (48mm) for that size bike.  If the riding ends up being more like 20% dirt, 80% pavement (or the dirt is very smooth) then you could downsize later to the Babyshoe Pass (42mm).

alex

---

From: 65...@googlegroups.com <65...@googlegroups.com> on behalf of Justin Hughes <justin...@me.com>
Sent: Tuesday, May 17, 2016 10:01:04 AM

To: 650b
Subject: Re: [650B] Re: What to build a custom around: 650b 42, 48 or 700c 38?

[William Lindsay]

Do Dia Compe 750s really clear 584/48 tires with fenders?  That's cool if they do, but I've got to confess I'm skeptical.  It seems to me that when you go all the way to 584/48 plus fenders, you need to go with cantilever brakes and ditch the idea of switching wheelsizes, or go disc brakes and ditch the idea of max fork compliance.  I'd love to see pictures if that's what you really are doing.  

Bill Lindsay

El Cerrito, CA

[Mike Schiller]

Panaracer is coming out with a 52 mm 700c tire in their Gravelking line in both slick and small knobs.  I've been riding the 700 x 40 SK version ( which measures 42 mm on 23 mm rims tubeless) and they are really fast rolling, supple tires.  Faster than a Thunder Burt IME. 

Personally I like the 700C size better than 650B on dirt rides.  On pavement I  don't see any difference.  I find the larger diameter tires roll through gravel and rutty roads faster.  I do have two 650B bikes as I'm just 6 ft tall and find that the bigger 700c tires ( over 48 mm) have some TCO on my 700C low trail bike with my size 46 shoes.

~mike

Carlsbad Ca

[cyclot...@gmail.com]

Or if you end up riding more dirt, being able to fit 27.5X2.1" Thunder Burts would be really nice.

[Jon Doyle]

I choose the SBH for my all-roads bike because it's super grippy, fast, and tubeless-ready. If it's heavy, I can't tell.

I've ridden BSP tires around Vermont, on NER brevets, D2R2, Green Mountain Double, etc. The BSP is great, but the extra volume of SBH feels more comfortable yet fast, especially tubeless.

My bike with SBHs: https://flic.kr/p/EfdRX4

Jon

Watertown, MA

On Monday, May 16, 2016 at 9:56:49 PM UTC-4, Daniel Jackson wrote:

[Justin Hughes]

I haven't personally ridden them, but Soma has the Supple Vitesse in 42mm. The website specs say it is lighter than the 38mm EL Barlow Pass model for model (both are offered in "regular" or "extra light"). 

On Tuesday, May 17, 2016 at 1:59:58 PM UTC-4, Alex Wetmore wrote:

I don't know where to find tires comparable to the Compass 42-52mm tires in the 622mm rim size.  The largest Compass tire in 622mm is 38mm.  It's a really nice tire and I use them on my commuter bike (which probably gets my most miles right now), but they aren't as nice as the wider tires on dirt.

alex

[olof...@gmail.com]

The bike on the picture is my custom Riv on tour sporting 622x35 mm tires (Panaracer Paselas). Brakes are GranCompe 450GC, standard reach. Same bike is today shood with 584x38 (PariMotos) and DiaCompe 750. Those brakes are aound 55 mm between arms and should take 48 mm tires, with a few mm to spare. Raids are wider. Fork and chainstays would not take 48 mm though. I have bought some 42 mm PariMotos to test, but the bike is presently 360 miles south of me..

 

What this means is that if you designe the bike for wide tires the difference between 584 andd 622 rims is no problem brakewise

 

Olof.

[Eric Daume]

That "crappily designed" Surly Cross Check has basically the same geo as your BMC Monstercross.

I'm surprised no one has mentioned the Soma Wolverine. Not low trail, but still BQ endorsed, and great tire clearance.

[Kieran J]

Yes, I know. I have a 62cm Cross Check as well. They are similar on paper, but quite different in real life.

I made the 'crappily' comment specifically in relation to TCO. The BMC does not have it, the CC has it in spades, even with narrow tires and fenders. The CC appears to have more reach that the BMC, so go figure.

KJ

[Harald Kliems]

On Tuesday, May 17, 2016 at 8:58:15 PM UTC-5, Kieran J wrote:

Yes, I know. I have a 62cm Cross Check as well. They are similar on paper, but quite different in real life.

I made the 'crappily' comment specifically in relation to TCO. The BMC does not have it, the CC has it in spades, even with narrow tires and fenders. The CC appears to have more reach that the BMC, so go figure.

Have they changed the geometry recently? My 62cm Cross-Check (I think it's the 2008 or 2009 model) does not have TCO for me with 38mm tires fenders, and up to size 50 shoes. I have my quibbles with the CC, but TCO is not one of them.

 Harald.

 

[Kieran J]

Well, if they did, it's regressive. Mine's a 2012.

TCO is not my only complaint about the CC, but I digress ..

KJ

[Nick Favicchio]

FWIW, I'm having this built right now....

https://flic.kr/p/Gkxowb

It'll primarily be shod with BSPs but has the clearance for a SBH or ever a Thunder Burt with the fenders off.

Don't think you need to lock yourself to just one tire size.

If you had something similar built for disks, a 700c x 38mm would also fit the frame. As would 26" and a balloon tire + a fender.

But I'm not a disk guy yet :).

[Jeffrey Kane]

So Daniel,

What are your conclusions (if any?) --- a quick read here seems to lean towards 700c. My two-cents: I can't imagine why 650b x 42 with room for 48's wouldn't answer your needs based on your well defined OP.

[satanas]

My truly crappily designed 56cm CC had TCO with 28mm tyres and no fenders, making it worthless for its intended purpose. It's also about the most dead feeling steel frame I've ridden, gaspipe cheapos possibly excepted. And yes I'm aware some people like them, but cannot understand why based on my experience.

Just because someone likes (or hates) anything doesn't mean some other person is likely to agree - blanket statements don't help anyone IMHO. Whenever loads of people start hyping something uncritically, I feel it's my duty to play devil's advocate and inject a bit of negativity. :-)

Later,
Stephen

[Nick Bull]

Surprised no one has mentioned:
Bicycle Quarterly: How wheel size affects bicycle handling. What are the optimum wheel sizes for various tire widths? Vol. 8, #3.

or
http://www.adventurecycling.org/default/assets/resources/20130201_mechanicaladvantage_heine.pdf

Conclusion: "Based on that test, we concluded that 700C wheels are best for narrow tires up to about 30 mm. For wider tires (30 to 42 millimeters), our testers preferred the somewhat smaller 650B wheels. Tires wider than 42 millimeters handled best on even smaller 26-inch wheels. It is no coincidence that the outer diameter of bicycle wheels has remained relatively constant, somewhere between 26 and 27 inches, since chain-driven bicycles were first were developed 130 years ago, despite much experimentation with other sizes. Motorcyclists have arrived at similar conclusions; they went to smaller wheels when their tires became wider and heavier, so that the rotational inertia remained the same."

Personally, I can't weigh in in any meaningful way because I haven't tried 700C tires bigger than 32's except for my (studded) Nokian Hakkapellita 700Cx42's.  Those tires have high rolling resistance and the handling leaves a great deal to be desired on pavement, but is fabulous on ice, go figure.

My next tires will probably be Rat Trap Pass 26"x2.3" to install on my MTB and see how I like those for gravel-road riding.  650Bx42's are fine most of the time, but in deep gravel they have too much of a tendency to dig in.

[Rick Johnson]

700C tires bigger than 32's

I have run the following over the last few years:

• Specialized Borough CX and XC Pro, 700x45. Now discontinued (but I see similarities in some of Specialized's newer tires). A very smooth and respectably fast tire. I'd still be riding them if I could (and had they worked tubeless but the tread delaminated within a few hundred miles). Actual size on a 29er rim at pressures <45psi ~ 38mm as I recall.
  
• Clement X’PLOR MSO, 700x40 (120 tpi version). My new favorite tire, works great tubeless. Also very smooth riding and nearly as fast as the Borough with better all season traction. Actual width for my setup again comes in ~38mm.
  
• Continental Cyclo X King, 700x42. Tired these this winter and still haven't taken them off. They are not nearly as slow as I expected based on the appearance. Great traction, very comfortable ride and surprisingly fast for their size/tread. Actual width comes in just shy of 40mm.
  

All widths noted are for the tire body and used to indicate volume. Variances in tread side knobs may add a few mm to clearance requirements.

Also have a set of Continental Cyclocross Speed in 700x35 set up on tubed rims. Not enough miles to report on them yet though.

Rick Johnson
Bend, Oregon

[Daniel Jackson]

Thank you all for providing yet another great rundown of ideas. This forum and the generosity of its followers always gives me renewed faith in humanity (and top notch bicycle advice)

I believe that this forum, despite its title, leaned towards 700c for my needs, constraints, desires. So that is where I am headed - in the form of the purchase of an existing bike from a fellow list member. It was made by Travis Cooper of Cooper cycles, and I believe fits the bill quite well for more pavement oriented rides of VT. 

This bike, too, will be a new experiment for me in low trail. To cover my desire for a custom, I've put my name down on Mitch Pryor's list for a bike designed around Compass SBHs. It may very well be the disc bike that you all too seem to recommend (still not sure), allowing for play with wheel sizes. I have time to experiment in the meantime.  

Again, thank you all for the great help.

Best,

D.