downtube

Great idea!

Thanks,
Yan

11oclock_rider

So I just got a Downtube 8H and it looks pretty solid. I really like the Sturmey Archer Hub. It shifts well and I just hope I can verify the claims of maintenance free. The only immediate "gripes" are that the gearing is a little high and it's weight. I weighed my bike and carry bag (both from Downtube) in at about 32 to 33 pounds. Is my scale busted? Can anyone else independently confirm the weight? I weighed myself multiple times holding the bike in the carry bag slung over my shoulders/back and took the difference with my body weight as the weight of the bike+bag.

At any rate, I'm curious, what are some reasonable, i.e., not terribly expensive, mods to the Downtube 8H that would lighten the bike and make it more commuter friendly? What kind of weight savings could be expected? I'm looking at a budget of between $100 to $200. Needless to say I want to keep the beefy internal hub on the back. ;-)

Nate1952

Greetings to everybody:

Somewhere on this vast thread I believe I saw a photograph of a DT with expedition-style handlebars installed.

If I did not dream that, I would be interested to know what problems - if any - this modification presented. And also any thoughts on any other kind of handlebar that would help me be more comfortable during long distance rides.

Folding up for airline travel is not a concern (yet).

SesameCrunch

Lots of good suggestions on modification in this ginormous thread. There are even some posts which include weights of some of the components, which is very valuable in helping decide what to jettison. Some quick/cheap weight-reducing mods include: new saddle, pedals, remove rack & kickstand, etc.

Also, many of us have put on smaller chainring (39t) up front to reduce the high gearing. While you're at it, remove and grease (or replace) the BB. Much valuable discussion about that in this thread. Sorry, you're just going have to wade through it.

SesameCrunch

I've installed one on my Full Suspension model. No problems with installing it. I gave the bike to a relative, so I don't have a lot of miles on that bar.

jondubus

LBS that did my mods weighed my '07 IXFS on their non-digital scale before & after mods: a disappointing 32.5 pounds before, 30.0 after these mods:
Ultegra BB & crank arms, Salsa 53t chainring, sram 11-32t cassette, XT RD, sram attack 9sp shifter, LX brakes & levers, Forte carbon bar, Forte 100mm stem, new '08 adjustable fork from Yan, IRC Metro tire up front. I had some of the above parts already and it totaled around $200 with LBS labor (GREAT work by Jon at Pittsburgh, PA REI). I have NOT yet adressed saddle & pedals and would also like to do something with the folding stempost if I could determine how much lighter the alloy 1" is than stock. Anyone out there? Gearing, shifting, ride quality is VASTLY improved-whole thing has been worth it. Compares well to a Swift but will fold smaller when i'm done with it.

See also my post titled: Downtube Ultegra? Why not?

11oclock_rider

Yep, I'm still trying to sort through this massive thread. It's almost as heavy as the bike . For pedals, would it be alright to put some clipless mtb style pedals on the bike? I assume they'd be alright with folding and storing in the bag. I already removed the kickstand. The rack I like, but I believe it does weight a lot. Any recommendations for a lighter weight rack?

What's your opinion of putting a 42T and then adding clipless. Would adding clipless provide a gain in energy transfer to the bike that would offset the need for an even lower chainring?

11oclock_rider

It's pretty amazing the weight. I was under the impression it was more around 26-27, but I guess that's just the frame?

Very nice. I'm finding the BB is a common mod for most ppl with the Downtube. The sizing is 116 by 13 correct? I also want to swap out the handle bar grips. Are the brake levers you have now, smaller than the originals? The stock levers seem big.

By the way, thanks for the replies to my post.

jur

You could use a seat post rack that you put on only when needed. The Topeak MTX rack does 20lb. Or, ThorUSA has some nifty light-looking racks that also remove very quickly when not needed.


Use 42T, you'll be fine. Clipless pedals don't improve efficiency by all that much I would say, they are more for keeping your feet in optimal position and for enabling pulling back at the bottom of the stroke. There is nothing magical in them. They wouldn't do something to the gearing or efficiency. You'd be able to spin faster, so they would help with reducing gearing.

jondubus

Quite welcome; I love this thread. I used a 113x68 Ultegra BB-LBS wrench at REI remarked that the resulting chainline came out identical to stock. Moreover, I've had NO need for anything else to hold the chain from slipping off-rode the revamped DT about 50 miles, did some serious shifting while riding over some ancient Pittsburgh cobblestones, no problems. Jon at REI did some curb jumps on his test ride with no problems either. The Salsa single chainring was necessary because it has NO ramps or pins that would otherwise help the chain slide over to another ring, unwanted in this case. That was another astute call by Jon at REI. Stock brake levers are straight; new levers have angles built inward toward rider to make a two-fingered reach much easier. Don't get me wrong, I now love my downtube for what it can do, but IMO there are serious discrepancies in the DT weight listings.

Baldone

YAN

Have those alloy stems for the 20" wheel set come in yet? I have been checking your site there and there and haven't seen them.

downtube

Good news I got another box of stems on the last container. Bad news it was for the mini 1" stem style. I would encourage you to either wait until we get more shipments ( early 2008 ) or get an older dahon style quill lower stem.

Thanks,
Yan

Avatar

Doesn't it interfere with the folding? I'm probably too lazy to QR the thing while folding.

invisiblehand

I think your description is right. Although keeping your feet in the correct position and being able to spin faster--both of which I find true when comparing to toe clips or power grips--is significant in my opinion. Presumably the effect is larger during rain storms.

-G

worker4youth

Question:

I just noticed that there is about a cm or play at the hinge of where the frame folds on my Downtube IX NS. I tried tightening it, and the screw at both the top and bottom would not tighten any further. Is this normal?

worker4youth

Anyone have any ideas? I am eager to ride my downtube again, but don't want it catastrophically failing on me.

BruceMetras

Are you talking about there being play at the hinge when the hinge is clamped shut?

worker4youth

No, there is no play when the clamp is shut (at least as far as my skinny arms can tell), only when it is loose or open.

jur

I'm sure I have seen this issue asked before in this thread, not too long ago, and Yan answered there was something wrong, a washer or something. Better check backwards in this thread. It was perhaps 6 months ago (bit of a wild guess).

jasong

worker4youth: 2 of my 3 infamous downtubes (06 / 07 models) had this problem (play in the hinge when it wasn't completely closed with the quick release). I was told by Yan that this wasnt correct. There were no missing washers, though. The frame halves apparently weren't machined properly or perhaps the hinge wasn't aligned correctly when welding.

See:

https://www.bikeforums.net/showthread...81#post3898181

J:"Should there be any play in the main hinge before closing the quick release?" Y:"The play you are referring to is not normal...." (2/21/07)

jrtozer

Just another data point for what it's worth, but I checked the bottom bracket on my brand new 2007 FS as suggested by many on the list. It came unscrewed easily and appeared well greased - No problems at all.

worker4youth

Do you believe it is dangerous to ride this frame? Have you noticed the play getting worse? I checked my downtube tonight, there does not seem to be any washers missing as well: there is one at the top, and one at the bottom.

I don't want the hinge snapping on me while I'm going down a hill at 25mph.

lecky

My first post here, so firstly, hello. Great forum; great thread. I got a NS VIII on ebay a week or so ago. I'm really happy with it. Got some stelvios on it and with a 130mm handlebar stem (also lots lighter) it fits me fairly well (I'm 6"2'), although I push a bit above the full extension indicator on the seat stem, and could do with some more for a perfect fit. I noticed that the seat tube only contacts with the seat stem for a 6cm length before the seat tube widens out in diameter, however the length of stem from the full extension mark to the end of the stem is about 16cm. You can see where I'm going... There's no disadvantage to the connection area of stem to seat post in using as much as 10cm more of the stem (well an extra 5cm would probably be about right for me), I'm guessing that the extra stress on the frame from greater leverage wouldn't be such a great issue(?), so is the issue one of stem strength? If so if I epoxy some well fitting aluminium tube inside the stem for, the bottom 20 or 30cm (?) I should be able to reinforce the stem greatly with a quite limited weight gain. Am I missing something - is this a bad idea?

jrtozer

Any engineers out there that can give an opinion about this - why is there so much extra post below the min line? I'd like to go 1.5" beyond the min insertion line too. As Lecky points out, it seems all that extra seat post down in the frame may not be doing anything. I even bought the "Butt Buddy" to extend my seat height, but given this new insight it seems like it would not create any less of a leverage issue than simply extending the post beyond min.

Thanks,
-J.R.

jur

I think the reason for min insertion is one of seatpost strength - you'll find, if you look at weight weenie seat posts, that the very light ones are shorter, eg the Thomson Elite is 400mm, while the Masterpiece only comes in 350mm. The tendency is there for all posts I have looked at. So lighter posts can only withstand a shorter leverage.

Having said that, there is also an issue about frame strength which is equally important. You can comprehensively wreck a frame if you have only an inch or 2 inserted and go over the inevitable bumps.

If your body mass is above average, I wouldn't mess with the insertions. But as a light weight I wouldn't hestitate to go a bit beyond.

As for handleposts, these have a long leverage on the head tube and headset, so leverage is an issue there too. If you ride carefully without pulling hard on the post while standing on the pedals in too high a gear, I wouldn't worry too much.