chico1st

can i use a chain tentioner and a front deraiiler on my single speed?
Right now i use a rear derailer (just for tension) and a front derailer.
When i change the front derailer I have to adjust the limit screws to get a good chain line.
Would a chain tensioner avoid this problem in any way? Im picturing those chain tensioners with the 1 pulley

simonaway427

why do you have a front derailleur on there? I don't get it.

BCRider

The setup would be cleaner if you went for a single front ring and a cluster at the rear. More speeds with smaller ratio changes between gears and your "tensioner" also handles the gear changes. It's a far slicker setup and lighter as well.

Monster Pete

Exactly. If you're thinking of having a double or triple chainring, front derailleur and chain tensioner, it's no longer a single speed and you'd be better off with something like a 5 speed freewheel and rear derailleur instead.

chico1st

heh ok true, its actually a 3-sp hub in the rear. I left it out to keep things simple.
If the chain tensioner wont create a good chain line then I will just keep my current setup, which does have a good chain line...but looks really hack.

eventually i plan to not have a triple in the front... or just not use the triple but for now i dont know what gear ratios i want on my all seasons grocery carrier.

Monster Pete

Ah that makes more sense. Would have been simpler to tell us it was a 3-speed in the first place

I don't think the single pulley chain tensioners can handle any significant difference in chainring sizes- you get issues with the chain skipping when on the smaller ring. You'd need either a double pulley tensioner or a short cage rear derailleur. Try adjusting the chain length so that the lower pulley isn't pulled too far forwards. A specific chain tensioner may look slightly neater but the derailleur will do the job just as well if not better- it's meant to deal with the chain running at an angle.

Let me know how this turns out- I have an old double crankset and a couple of deraillers lying around...

chico1st

im good thanks pete
i feel as though the Sturmey 3-sp doesnt have a large enough gear range for an all-seasons urban commuter/utility. The alfine looks pretty good but really I would just want one more gear on my 3 sp to extend my gear range. I think sturmies are 70%-130% and something like 50-130% would be good.

thirdgenbird

monster pete is correct. you will get skipping (not a good thing out of the saddle) if you dont use a two pulley tensioner or RD.

Monster Pete

Another option with the SA 3-speed is to install two dished rear sprockets back-to-back and use a rear derailleur to shift between them. The overall result is the same, but may be a bit neater. However you do it, I would set it up with 'half-step' gearing, so that a shift with the derailler gives a gear halfway between the hub's gears.

LarDasse74

In general, single pulley chain tensioners will not be able to pull enough slack. I have an Alfine double pulley chain tensioner and, according to the instructions, there is a limited difference it allows between chainrings. FOr this reason, a locked-out rear derailleur is probably the best chain tensioner going for your setup.

Kimmo

It should be possible to run a single-pulley tensioner with half-step rings, I'd have thought

BCRider

I like this option if you can find the pulleys to make it work.

THe other option would be to commit more fully to the idea of going IGH and get a 5 or 7 speed hub and lose all the extra gearing baggage. I know this means more money but if you're going to have all that rear end "junk" then you may as well use it for shifting the chain over a regular freewheel or cassete and be done with it. The whole point of going with an IGH is to do away with all that external stuff and get down to two sprockets and a chain only so you minimize the amount of stuff that picks up muck and needs cleaning. By insisting on keeping the front derailleur you just end up with all the same "junk" on both ends of the drive train.

raspberri

i think single speed mean free of any shifting mechanism...?

fietsbob

Single speed chainline would be applicable to your IG hub's chainring
And rear cog alignment, they are to both be equidistant
from the centerline of the frame, the wheels track on that centerline.

FWIW
Newer Sturmey-Archer for Brompton, BWR hub, and its predecessor, sourced from Sachs/SRAM, have a short
cassette driver on their 3 speed hubs, and 1/2 step with a 13/15 pair of 3/32 thick cogs .
people have put double chainrings on their Bromptons , offers a range change up front.

the brompton design has a chain-tensioner as part of its folding mechanisms.

...

Way back , my youth, [JFK was alive] I built up my 3 speed into a 27 speed.
found a single machined steel 3 cog cluster, that was made to go on AW3
hubs, then put a triple crank on, that used the same cottered BB.
nothing special, all parts steel, used 3 downtube levers
to shift between the 3 options in the 3 different places.