SesameCrunch

I have been lusting after the VIIIH's recently. The range and convenience of the 8 speed internal hubs just appeal to me, particularly in a folding bike. So, I saw one on Craigslist and had to go get it. It's in great shape, having been ridden only 5 times or so. I gotta stop buying bikes!

SesameCrunch

Ingenious solution! I may "borrow" it some day!

WrencherWOAC

What do you think of the gearing? How about the chainline?

Wavshrdr

I had one of the first VIIIH's. It has been a great bike other than its geared a little tall. I wrote a detailed review last year on it. You could help the gearing a bit by going with a bigger rear sprocket or a smaller front.

SesameCrunch

Yes, I have appreciated and enjoyed your reviews of both the VIIIH and the Mini (bought one for my mother in law). I plan to put a new crank with 39t chainring like PineCone's setup. That would give me 34-104 gear inch range. Perfect configuration, in my opinion.

WrencherWOAC

Search for "folding bicycles" on [URL="https://youtube.com/"]YouTube[/URL

Some useful information. I haven't found any Downtube videos so far which surprise me.

JugglerDave

I just got my IXNS via UPS, very exciting. Sometime soon I hope to trial a bike commute via Amtrak (Philly to Paoli).

Reading thru the forum I am trying to assemble a list of 'top 10 upgrades', with train commuting in mind, and keeping about $100 budget.

1. Velcro straps to keep frame together on train
2. Replace Bottom Bracket. Sounds like it's $40 for the part but I might need to buy tools to do this.
3. Replace seat with lighter one. Any suggestions for an inexpensive, light, comfortable seat?
4. Remove kickstand and possibly rack (I use a messanger bag) to shave a couple pounds.
5-10 ???? Looking for suggestions here!

SesameCrunch

Dave:
You can get a sealed Shimano bottom bracket from Bike Nashbar for $13 https://www.nashbar.com/profile.cfm?c...tom%20Brackets.

The BB removal tool will cost about $7 https://www.nashbar.com/profile.cfm?c...racket%2FPedal, but there are other tools required to remove the crank. Or you can have the LBS install it.

You actually don't have to replace the BB. What's vital is that you grease it well - both the bearings and the outer shell. That's all.

It's hard to recommend upgrades without knowing your riding conditions. Try it out for a while and then see what you want/need. The bike you got is perfectly functional, but there are also endless number of things you can do it, as you've seen from this enormous thread.

JugglerDave

Thanks. I had written down the "UN 53" model, the link above is UN 52 (don't know what the difference is). But in any case it doesn't look like they have the 68x115 size in stock for either part.

That's the plan. One concern is whether I have to lower the gearing due to a 300 ft elevation 10% grade hill, but I think I should be fine with the IXNS low gear (versus the VIIIH hub which seemed to have a taller lowest gearing).

SesameCrunch

Keep in mind, the critical thing is the GREASE, not the intrinsic BB itself.

I really like mcgurme's creative solution (just a few post back on this page) on doubling up the front crank and then shifting manually. It's cheap and functional. I find that I do very well 99% of the time on the 53t chainring, but with his solution, there's a remedy for the 1% of the time when I really, really need a low gear. If you're going to be riding this bike a lot, changing the front crank would rank high on the list of upgrades.

kenmacpr

First post, I've been reading this forum for about 4 straight hours now (kids are home from school because of snow) and can't find what I'm looking for. How suitable is the H to a Rohloff conversion? It sounds like the SA hub spacing is narrower than the Rohloff? The reason being is that I plan to use the bike for multiple functions: all weather/all purpose grocery getter (literally, with trailer), alternative to my road bike and travel bike. Since I live in an area with steep hills, I need lower gears when pulling the trailer with $100 worth of groceries and want higher gears for fun, a wider range than I can get with an 11-34. Plus I think the Rohloff is really cool and I really want one -- and the price of a DT puts me $300 closer than I would be with, say, a Swift (which means it may actually be financially feasible). My other alternative would be the NS (or a Swift) and either install a double chainring (manual shift w/o FD) or buy a second rear wheel with the Capreo 9/28(?) hub/cassette.

If Yan says the dropouts are spaced properly and already long enough, I'm going to start getting excited. Better yet, any plans for an eccentric bottom bracket shell ala the Thorn Raven and any decent tandem?

bookishboy

Well obviously the difference is "1".

Sorry, I know it's terrible and I couldn't resist it.

downtube

I am not familar with the Rohloff hub, however the specs on the Sturmey Archer (from https://www.sturmey-archer.com/hubs_8spd_XRF8.php )are:

• Hub Shell Material - 6061 Aluminum
• Axle Diameter - 13/32” Slotted
• Axle Length - 155.0mm
• Over Locknut Dimension - 116.0mm
• Right Axle Protrusion Length - 19.5mm
• Left Axle Protrusion Length - 19.5mm

Wavshrdr

I did this a long time ago on my Swift. I wanted a high/low range more than needing to shift on the fly. My 8spd internal hub gave me great range for most things and I didn't need the complexity of a front derailleur but with the chain rings I could have it when I needed it. I have it setup about right for load/unloaded conditions. I can also kick the chain from the bigger to smaller sprocket while on the move if needed.

SesameCrunch

I assume you had to put in a chain tensioner as well?

WrencherWOAC

By now some of you might have guessed from my user name that I might be a "female bicycle mechanic" and just like to set guys off once in a while. The answer,"Online Street Theatre, sort of.

mcgurme

You don't strike me as female in your approach to the list. It's the small things, like writing long posts about "physics" which weren't really.

I only bring it up because SesameCrunch, earlier in this thread, referred to me as "he". I wasn't offended to have my gender mis-labelled, and I wasn't going to say anything about it. However, you changed my mind, trying to blame the posts on being a "female bicycle mechanic," whatever that means. Real female bicycle mechanics wouldn't be blaming their follies on their gender and claiming to enjoy riling the guys. That's the last thing a woman on a male-dominated list would do.

Let's get back to discussing the bikes, shall we? like this

On your blog, you wrote:
Actually, it's kinetic energy that counts. K=1/2 I W^2. (W=Omega here). You'll note that larger mass distributed further out leads to larger I, since I=mR^2. Interestingly, the biggest contributor to the moment of inertia, I, is the radius (see that R^2?), not the mass (which is only linear in this equation).

So, it takes a certain amount of energy to get the wheels going, which is higher for larger and/or heavier wheels. HOWEVER, the first law of thermodynamics (conservation of energy) says that that energy must go somewhere. Here are the places it can go:
1. Viscous friction, i.e. warming the air or creating sound (which eventually dissipates to heat)
2. Tire or wheel heating and/or noise generation due to displacement of tire/wheel parts (including bearings)
3. Ground heating and/or noise (shockwave) generation due to displacement of the ground as tire rolls over (that's why riding on grass is so much more work, because it displaces more than pavement, absorbing energy)
4. Friction in your braking system as you stop

There are NO other places that energy goes, once it's put into the system. Period.

The only situation where rotating mass matters more than any other kind is when you are braking. You put energy in to get the bike going at a certain speed (both linear and rotational energy), then you suck all that energy out (turning it into heat) by applying the brakes. So if you had to put more in to get it going, you suck more out in stopping. However, that doesn't make a big difference for a road race, because people aren't typically braking much nor stopping much in the middle of a race.

So, then, why do people care about super light road wheels? For the same reason they care about any extra weight on the bike. When you go up a hill, the energy you put in is mostly lost coming back down. Viscous friction: it scales with the square of velocity (v^2). So as you descend, the increase in speed burns off the extra energy you invested in going up the hill much more rapidly - so you don't get it back as you go up the next hill. In other words, dragging any mass up the hill (i.e. building up potential energy, mgh where m is mass, g is gravity, and h is height of hill) results in wasted energy on the next descent. That's why you can ride down the side of a mountain and you'll top out at a certain speed where the conversion of potential energy to speed equals the loss of energy to friction. By the time you're at the bottom of the hill, you'll be lucky if you make it 100 feet up the next one by coasting (i.e. exploiting whatever kinetic energy remains at the bottom of the hill - no potential energy is left). All the energy you put in just got sucked out. The bigger the mass, the more energy you put into dragging you and your bike up the hill, which just got wasted coming back down.

Not convinced? Then I ask you to think about a simple question. Why is it that people don't road race on 20" wheels? Remember above? Kinetic rotational energy scales with the square of the radius. So, if rotational "mass" (i.e. energy input to a rotating wheel) was so important, people would be racing on smaller wheels (but not so small that the features of a smooth road begin to substantively increase the total distance travelled due to tracing the contours instead of spanning them, but this shouldn't be a problem with 20" wheels). No, the typical 700c racing wheel is near the sweet spot in a tradeoff between aerodynamics (viscous friction), rotational energy (more energy invested to get it moving than smaller wheel), bearing friction (lower Omega with larger R means lower bearing friction losses) and tire inefficiencies (a complex equation having to do with pressure, width, material properties, and how those add up to heat generation in the tire).

So, all that said, am I going to give up on making my wheels lighter? No. There's an important mental component: light wheels "feel" faster because they accelerate more quickly - i.e. given a certain constant energy input (say at V02 max), one will get up to speed a bit quicker on wheels with lower moment of inertia, I. This has a positive mental impact, even if it matters only slightly on the scale of total energy input to a bike. (actually, it's good for situations such as city riding or mountain biking where the brakes are frequently applied, too). But if it comes to a tradeoff between shaving a pound or two on my bike, versus shedding an ounce on the wheels, I'd take the pound or two on the bike. The next time I go up a hill, my quads will thank me.

Actually, I do agree with you here. It's a lot cheaper (and healthier) to loose a few pounds than to go out and buy titanium components. But it sure isn't as much fun!

SesameCrunch

No serious post here - just a picture of me and my kid having lots of fun on a Downtube.

I added a child seat to the converted recumbent. Now my 3 year old and I can both enjoy the ride!



Video here: https://www.youtube.com/watch?v=8Kt_d3fy_pU

jur

absolutely Awesome!!!!!!

BigMacFU

Sesame, that is too cool!!!!

lOUIE

Just received delivery of my VIIIH. How do I get the plastic smell out of the bag? It is really bad. The bike is great. Will try riding it tomorrow.

DVC45

To multiple DT owners.....
Which DT gives a faster ride? The S.A. hub or the derailure type?
Thanks!

juan162

SesameCrunch,

When I have a child, I will have to do a similar conversion. That's awesome,

Juan

SesameCrunch

Derailleurs for sure. Internal hubs are heavier, don't shift as quickly and aren't really built for stomping on.

SesameCrunch

Thanks for all the kudos on the child carrier. I think the cute kid in the back makes the picture.

You want to borrow my child for a couple of weeks?