hedgeapple

I've seen Berto's charts before and I use them. Note that he includes tire widths, but nothing is said about wheel diameter. I'm assuming he's working with a 700C (622) wheel, making the chart inapplicable to any other wheel diameter. Volume calculations have to account not only for tire width but for wheel circumference, too, which is greater for a 622 than for a 584 or 559. My calculations do account for circumference; I'm sure they are still crude, but consistently so.
About my atmospheric example: It ignores temparature. Since temps, which go up with compression and down with elevation (in the troposphere), and geographic displacement of atmosphere (ie, mountains) are part of reality, I think the 500mb level probably defines something less than half our air, but I don't wanna argue about it.

oldskoolwrench

A question; would you lean towards traditional drop bars (Dream, Rando, etc.) or dirt drops (Woodchipper, Midge, BB-1)? Personally, I would choose traditional... mainly for the uniform width at the hoods.

bikemig 

I'm leaning towards the trekking bars just because I've never tried them before. It will also be less expensive since I would need a nitto technomic stem or something similar for drop bars. If drops, I'd be tempted to go with randonneur style bars since the upsweeps on the flats are useful on a mtb conversion.

Jim Kukula

My formulas estimate that pressure should go down as the square root of the wheel diameter.

https://www.schwalbetires.com/tech_info/tire_dimensions gives a circumference of 2075 for a 50-559 and 2280 for a 50-622. So the 622 should have about 5% less pressure than the 559.

hedgeapple

https://www.schwalbetires.com/tech_info/tire_dimensions - that's an interesting site, I'm gonna have to spend some time there.

My calculations use a circumference that is really the estimated mid-point of the tire's cross-section. Reasoning: 1) I'm figuring volume, 2) tire curvature around the rim would yield greater volume to the outside of that mid-point, which I assume would be mostly compensated for by 3) lesser volume to the inside of that mid-point. What I do is add two times 50% of the tire's cross-section (for a 50mm tire, that would be 2x25, or 50mm) to the rim's diameter (in this case, 559, for a total of 609) (I'm sure you've already noted the simple way to do this is just add the tire's width to the rim diameter). Considering the resulting circumference (609x3.1416=@1913.2) as a cylinder length, I multiply it by the tube's cross-sectional area (for a 50mm tube, 25x25x3.1416=1965.5) to get a volume (3756568.2 cubic mm). I used the same process to figure volumes for the other tires. I did not account for tube wall thickness, and I'm assuming the given width is an internal dimension and that the interior is round, unless I'm in the saddle. That would mean compression.

Regarding drop bars: mine are conventional, and their one short-coming I've found is that the bike is harder to control in soft stuff. The WTB mountain drop bar formerly used on Raleigh's Sojourn would help, but I don't have one and I'm getting by without it.

I should mention that the SC30, compared to the Rockhopper, has 1/2 inch less BB height, 10mm longer chainstays (435mm, and I'd like another inch), and noticeably less front-center.

I rode the SC30 about 27 miles this morning, on grass, dirt track, gravel, sand, highway and city street. The bike works very well.

Jim Kukula

Wikipedia says your volume computation is exactly correct!

https://en.wikipedia.org/wiki/Torus

I use the outside diameter because I am looking at the area of the contact patch as a function of the tire drop. All the action is at the outermost circumference of the torus.

mev

This past month I've toured ~1750 miles on the setup shown in the photo. While I normally tour with Trek 520 (and before that Cannondale T1000), I had the mountain bike from Tour D'Afrique riding and followed that trip with some additional touring in the US. I put two panniers on the back rack and two panniers on the Extrawheel trailer behind. Here is how my list would compare to your above:

1. In past I've preferred the Aluminum ride (on Cannondale T1000) but steel on this bike is fine.
2. My suspension fork doesn't "suspend" much since it is either in lockout mode or I'm putting enough weight that it mostly stays in place. Not a big deal in this case, though agree if I had a non-suspension fork that likely is as good for mostly on-road touring.
3. I don't get into the drops on my touring bikes, so drop bars weren't a big deal. Instead, the bar-ends do give me some alternate hand positions.
4. So far these shifters have worked fine, though agree with you on friction shifters for simplicity.
5. I really like the disc brakes. Lots of extra stopping power for myself and my gear and keeps the wear off the rims. Hydraulic brakes could have been a finicky alternative for touring, though so far I've been lucky.
6. I'm heavier, so rear wheel is 40 spokes and front is 36 spokes. I'm still figuring out this Extrawheel trailer but it might work better to have same spoke count in its rim as my rear wheel so I could cannibalize if necessary.
7. 26x1.75 has worked well as tires for me. Wider doesn't seem to make much difference for me, particularly on road.

So far the trailer/pannier combination has worked well. The attachment is at the rear wheel so it tracks well.

mattgmann

This is my commuter mtb that I've been experimenting with some overnight trips hoping to start some real touring. It's a voodoo bizango frame, rhyno lite rims on xt hubs, race face crank, deore mix drivetrain, Scott AT-2 handlebars, xt disc in front, v-brake in rear.

I'm working on an upgrade to a 10sp slx drivetrain atm (buying up parts one at a time). It also recently received a brooks b17 to replace the nashbar ass-cracker saddle.

This bike has been serving me well for a few months in it's current configuration. The drivetrain upgrade is fueled by a waning rear cassette, constant adjustment needed on the derailleurs, and I just don't like the race-face crank. Are there any more upgrades that would be worth spending on before I take this bike on some longer trips? ( I love the scott mtb bullhorns btw).

seat_boy

Nothing to add but, nice looking Voodoo!

bmwstbill

A bump for this thread, must be some more conversions out there, or is there another thread on the same subject I am missing?

Here's mine to throw on the fire.



bill

fietsbob

Advantage to a MTB-> trekking bar conversion .. is you really dont have to invest that much money

into the project,, with a Drop bar conversion you can shell out significant Coin.

particularly if wanting STI Brifter's and such ..

fietsbob

Not really much of a conversion since mostly it came like that, (used)

just I had to raise the handlebars with the stem riser , the bars were already of a Trekking type.

https://www.cyclofiend.com/working/20...clark1008.html

bmwstbill

That's a darn nice bike, the clear multiple pics are appreciated.

What make is the front fork and how does it work/do you like it?

What racks are you using? Tubus?

What tires?

bill

fietsbob

Front fork Spinner.. it was re machined for the Company, then painted, short 35mm travel ,
it came as Is ..

If building from scratch .. I wouldn't bother . but in the Signature build, menu-list Program ,
at Koga.com in NL has a similar Option.

Koga Gets bulk orders for parts , so the Kickstand on the front rack braze on is exclusive to Koga.
they do buy Tubus racks.

link may take more Koga Site navigation , but they do maintain a back model spec list , still .
https://www.koga-signature.com/Build-...px?language=en

RhinoDave

I have a 1998 Schwinn Moab One that has been configured several ways over the years and was used to do the GAP trail and C&O towpath a few years back. It has been a single speed, a 1X9 commuter and grocery getter. An upright flat bar tourer with MTB shifters and V-brakes as well as a drop bar tourer with cantilever brakes and interrupter brakes. It is currently set up with MTB riser bars and MTB STI shifters.
As a 1x9 commuter:


Loaded for the GAP/ C&O trip:

hedgeapple

This is my rockhopper (or plop-hopper - I live on a farm) in final form before we built the SC30 Raleigh that replaced it and inherited the saddle, rack, and fenders. This was not a bad bike at all, but the SC30 rides better (it is a comfort bike, after all), is faster, and accepted drop bars with ease. Having rigid forks, it will also be easier to set up for front-loading.

revcp 

A conversion really doesn't have to be that expensive. I converted an '86 Schwinn High Sierra (triple butted 4130 cromoly,18.5" chainstays, midfork mounts for panniers) to a drop using a 1985 Miyata 210 donor. The Miyata was in tough shape so I picked it up for $15. The stem, bars and brake levers went to the High Sierra (and the bars are the randonneuring style you're looking for). Only thing I had to buy for the conversion was a pair of $20 suntour barcons off CL. So it was a $35 conversion, with parts and a frame left over for other projects. Oh, and I decided to splurge and put on CST Cyclone 2.4" tires (another benefit to the High Sierra -- it will fit even wider tires than 2.4").

Nycycle

Pulling trailer with my MTB aluminum frame was great at the time. Some how my rear skewer came a little loose and my axle started jumping around, I noticed something wrong, tried to tighten it up, too late drop out gone.
So I went for the smooth ride LHT, traded Nashbar for BOB, Between rides now, bike all buried by camping gear.