bostontrevor

Does anyone know if you can use a friction shifter like a barcon or downtube shifter with a Nexus geared hub? I did some searching here, but I only found one cryptic reference to needing perfect indexing to shift a Nexus hub.

jim-bob

I'd be pretty dubious - it seems like there'd be a lot of potential for throwing it in neutral. I'm sure it could be made to kind of work, but you're best off using their icky twist-shifter.

genericbikedude

and even with the icky twist shifter, its still a little sketchy around 4th and 5th gear.

sorry to thread-jack, but can chain tensioners be used with internally geared hubs for use on vertical dropouts? I don't see why not off hand, but you never know... thanks!

dafydd

i wouldn't try friction, although i've been told the pull ratio for nexus shifters is the same as other shimano indexed shifters. as the nexus revoshifters look the same as normal revoshifters and given the potential savings in tooling/die making, i wouldn't be surprised at all.

grolby

No.

This is not because of chain tension, but because most internal gear hubs, including the Nexus, must be installed in horizontal dropouts to prevent torque from rotating the axle. The Rohloff Speedhub is an exception to this rule, but only under particular circumstances and with particular versions of the hub.

HillRider

There are chain tensioners made for fixed gear/single speed bike with vertical dropouts so I don't see why they wouldn't work with an internally geared hub too. Try Sheldon Brown's Fixed Gear web site area as I'm pretty sure he sells them.

grolby

Don't waste your money. As I said above, good luck finding a hub that will work with vertical dropouts. Vertical dropouts are great for derailer bikes, and close to useless for most anything else.

On a more nit-picky note, chain tensioners are not intended for and should not be used on a fixed-gear bike, as they will self-destruct as soon you try to slow down by resisting the pedal motion.

genericbikedude

Right, we all know (or should know) that you cant use a chain tensioner on a fixie. But what about a sturmey?

bostontrevor

Actually, I think the reason that you don't want a tensioner on a FG is that bringing the bottom portion of the chain run under tension can either over-extend the tensioner or smash it into the chainstay if you have too much excess chain. Keep it reasonable, though, and you shouldn't have a problem.

A planetary gear shouldn't be any kind of problem except possibly if you have a coaster brake. Then the above considerations apply. Otherwise it's no different than a single-speed setup where a tensioner is a-ok.

dbg

Nope. I built up a jig to test pull distance (would have posted but the pictures all turned out bad). The nexus 7 (8 is probably similar -- haven't tested it yet) has approximately twice the pull distance for each click as a standard shimano 8 speed shifter. I planned to use some 8 speed brifters coupled through a travel-agent for my nexus-7 touring bike (lowest click would drop into nothing). From the jig it looks like it could work. Friction shifters would be stupid.

BTW, chain tensioner should be just fine for vertical drops. I plan to add a rear derailer to take up the slack for using two front chainrings with my nexus-7.

bostontrevor

Why do you say that? I have nothing STI but I do have some old SunTour barcons. I've got a custom singlespeed frame in fab but I've been toying with the idea of building up an internally geared wheel. Since I'll already have the brake levers all setup from the fixed or SS configuration, it doesn't even make sense to add a brifter (expense aside). So what's so terrible about friction shifting assuming that it's reasonably easy to pull an appropriate amount of cable?

Grand Bois

BULL!

https://community.webshots.com/photo/...06706550jGoqAL

genericbikedude

the beauty of ratcheting suntour barcons (best shifters ever) is that you can continue pedaling whiole you shift to dial in the shift precisely, aided by the ratcheting mechanism. with an internally geared bike, you dont have a misplaced chain inbetween speeds, you have dead air. no fun.

dbg

You could try it. I'm not sure what happens between gears. It might spin freely until you find the next position. I'd also worry you won't have capacity for all positions. It requires about twice the pull of standard rear derailers.

bostontrevor

A travel-agent type setup should be able to give me enough pull if that's an issue. Finding the stops seems to be more of an issue. If I ever get around to building the wheel, I'll have to give it a shot.

It seems like there's renewed interest in planetary hubs, I don't know why Shimano hasn't produced a drop-bar compatible shifter. Hell, even a crappy old thumb shifter like an old Sturmey Archer (or old Shimano) would work acceptably well. Better than the twister on the bar plug trick.

grolby

And you've proved... what? That with a Magic Gear or an eccentric hub, you can make a SS or fixed work with vertical dropouts? So what? Either of these solutions are either an expensive technological fix, or require an absurd amount of calculating and kludging to get them to work. I'm not saying that there's anything WRONG with vertical drops, as they are indeed very nice for bikes that will only use a derailer. They are simply not versatile enough for most other uses, at least not for easy conversion. Chain tensioners have made singlespeeds no big deal, but if you don't want a chain tensioner or want a fixie, or a bike with internal gears, it's going to take a lot more work than if you had started with horizontal drops.

Anyway, I'm not sure how I could be more clear, genericbikedude - there's nothing wrong with using chain tensioner on a bike with a Sturmey-Archer or other internal-gear hub, but there's no point in doing do. Chain tensioners are to take up slack on bikes with vertical dropouts, and you can't install one of these hubs in a bike with vertical dropouts. With S-A hubs, this is because the axle has flats, which will lock it in place within the dropouts and prevent it from rotating from the torque on the hub. I'm not very familiar with too many other internal gear hubs, but most of them also require horizontal dropouts, for what I'm assuming are the same reasons.

jim-bob

I dunno, man. I hate the travel agent with a passion. The way it bends and kinks that poor cable just gives me a headache.

bostontrevor

I dunno, it doesn't strike me as being so different (except in effect) from a classic gear wire pulley.

jim-bob

Ever used one? To do its increasing radius trick, you feed the cable in through one part of the pulley, run it through a little sharp hole, and then it makes like a 130° bend to get back to the outside of the pulley. Trust me, man, it's yucky.

Phantoj

I like Sheldon because he seems to actually try stuff out before spouting "knowledge":

https://www.sheldonbrown.com/nexus-mech.html

bostontrevor

Ah... I'm looking at a closeup now:

https://www.performancebike.com/produ...00/00_2988.jpg

Yeah, it doesn't look great, but the cable should remain motionless at the point where it passes through the hole. It's effectively a two cable setup with the input end affixed to the small pulley and the output end affixed to the large one to gear up the travel. Yeah?

jim-bob

Well, sort of - but it uses the same cable for both bits, and that stress riser at the bend is a b*tch. The first couple times I tried to feed the cable through, I got a pretty nasty crimp'n'fray going on, and I can't imagine it's good for the cable's longevity. I got 'em off my bike as soon as possible and switched to good ol' cantis. Now, you're just thinking of using them for shifter cable, which won't have quite the same catastrophic results if it fails.

..Still, I'm against it. Just sayin'.

Grand Bois

I've proven that your statement is incorrect. My single speed Trek was easy to set up. I didn't have to use a half link or an eccentric hub and I did not modify the dropouts in any way. I experimented with cassette cogs and chainrings until I found a combination that worked. I hit it on the second try. I was actually disappointed that it was so easy because I enjoy tinkering. Because I have vertical dropouts, my wheel is always aligned perfectly and I don't have to carry a wrench to adjust chain tension. I can use a quick-release hub. The chain will tell me when it's worn out and needs to be replaced by becoming loose.

The only drawback I've found is that I can't easily change my gearing, but I haven't found it necessary to do so. The 46X18 combination feels just right in the hills where I live.

I plan to experiment with a Shimano Nexus hub for it as soon as I can find one cheap.

grolby

In what sense? I said that it's harder and takes more work to set up a bike with vertical dropouts as a singlespeed, fixed-gear or internally-geared bike. Do you mean to suggest that if you had two identical frames, except that one had vertical dropouts and the other one had horizontal dropouts, that you would still have chosen to use the one with vertical dropouts? My statement - vertical dropouts lack the versatility of horizontal dropouts - remains true. It goes almost without saying that close to nothing is actually impossible, but some things are going to take more work. I do see, however, that the post that you responded to was too strongly worded. Instead of "vertical dropouts are close to useless for anything but derailer bikes," I should have simply said what I meant - vertical dropouts are not versatile, making life a little bit to a lot more complicated if you don't want a derailer set-up.

Phantoj, thanks, I had forgotten where that article by Sheldon was, but remembered reading it. If I had, linking to it would have been the best answer I could give. The shortest, most practical answer to the question is still, "the chain tension is the least of your problems." Most people, for good reason, are rather averse to drilling holes in their dropouts. Still, I concede the point - it can certainly be done. I applaud anyone who takes on this project, and I applaud still more anyone who pulls it off!