neilfein

I've been having problems with my 3-speed Curve for some time now. The gears don't shift smoothly, and I sometimes can barely access first gear.

For a while I thought it was simply tension on the shifter cable near the hub. I would experiment getting the tension just right, and sometimes it works for a while.

I also had problems with gears seeming to slip from time to time, usually when going uphill and there's I'm pressing harder on the pedals. It would tend to crop up when I had recently done work on the rear wheel - changing tires, usually. It's difficult to get the rear wheel in just the right position.

Now, I suspect neither of these may be the cause. I've gotten the tension on the shifter cable and on the chain correct, I think, and the gears keep almost-slipping and the shifting still doesn't work. Am I making false assumptions here? Anyone see this before?

BruceMetras

Most problems with hub shifting problems on folders stem from cable problems and not the hub itself.. long enclosed cable runs and continually folding it in half on itself make these the likely culprit... disconnect the cable from the hub.. actuate the shifting manually.. if it shifts fine, then the cable, or possibly the shifter is at fault.. also look at the cable guide at the hub(if it has one) I had a D3 with a Sturmey and the plastic cable guide was broken and would not let the gear actuator move smoothly in and out of the hub... Sram 3 speed hubs should last a long time if not abused.. also, if you don't already use a chain tug to keep the wheel from sliding forward under force, you might consider installing one.. not only does it keep the wheel from moving forward incrementally (changing the cable tension in the process), but it can also aid in getting the wheel back in the same place in the dropouts after a wheel removal..

neilfein

Pulling the chain that goes into the hub itself, it seems to move smoothly. It's also screwed in all the way. (I had it come loose once when I was giving he bike a cleaning, and thought I had broken the hub!)

I'll take a look at the cable guide and routing. The cable guide is kinda beat up.

What's a chain tug? It sounds like it could be very useful.

BruceMetras

There are a few different styles.. but basically the same idea.. you want something for a 10mm axle.. something like This.

vincentnyc

u know u suppose to stop pedaling while u shift gear, right?

jur

I would say many shifting problems come from dirty cables.

I would replace the cable or at least, pull the inner cable out of the outer housing, quirt WD-40 down the cable housing and blow it clean with a compressor. Wipe the outside of the inner cable apply some Boeshield and reassemble. If it has kinks and won't return to smooth movement, replace.

(My Birdy's rear cable deteriorates and when I do this, it returns to as-new performance.)

tcs

SRAM T3 manual:
"Keep pedaling without effort as you change gears."

iMotion 3:
"Load shiftable. You can shift while standing still or while riding your bicycle."

Best,
tcs

Dahon.Steve

The Sram T3 is rock solid but I would not shift it under load. You do have to let up when going up hill regardless of what the instructions state.

neilfein

Thanks, everybody! I think several of the suggestions above are issues.



The drive-side retaining bolt is stripped, and won't hold the wheel in the correct location.


The cable guide itself doesn't turn all that easily.


You can see scarring on the frame where the wheel gets pulled forward in the dropout. I'll have to order a cable pull.


The cable will only come out of the hub at this angle (or straight up). You need to loosen it a bit to get it angled so it sits correctly in the cable guide. Might this be causing the issue with shifting?

I think an email to Thor is in order.

neilfein

...and here are more pictures:


The shifter cable attachment and (I think) the guide inside the shifter housing


The thingy that clamps onto the shift cable and pulls on the chain from the hub


The shifter cable attachment and (I think) the guide inside the shifter housing


The cover to the cable guide

a quickr pickr post

jur

Wow, that's a mighty short piece of axle you have for threading the axle nut on... no wonder it stripped.

brakemeister

ok lemme try
1. looks to me that the cable is totally gone. replace with a new shifter cable ( its generic)
a new outer housing is a couple bucks, slurge and get a new one also
2. I will look if I have a cable turn around guide floating around
3. get a new axle nut .... from Harris Cyclery I dont think I have them
4. unscrew the link shifter chain half a turn so it can point forward without binding
5. check if you have more axle on the non drive side, if yes than loosen the cones and shift the axle more to the drive side, so you have enough thread on both sides... look if HArris has a thinner washer with a leg, the little leg is important as it prevents the axle from rotating
6. looks to me that the wheel could go a little more upwards in the slot . make sure you got both sides straight and have the apropiate torque on both axle nuts ( in the description which came with your bike )
7. no axlestoppers needed as the slot is horizontal and not vertical

okidokee :-)

Thor

neilfein

Thanks, Thor!

Okay, sounds good. What's the axle nut part I need to ask for?

That's what I've been doing. It's good to know I've been doing something correctly!

Will do. What are the cones?

By upwards do you mean towards the front or the back?

This is the same as a chain pull? I thought that the whole point, that the wheel can get pulled forward in the dropout by the chain.

brakemeister

my fault
sure the curve has long slots ( i always mix up horizontal ,,lol ) yeah a tug like you have on your link should work

checked in the warehouse if I have the roller thingy for the chain to go around..I have an SA one but not the sram thingy ... also Harris is the place.... dont have part numbers but if you tell them what year bike and 3 speed and such they should be knowing what you need

Thanks Thor

tcs

Availability of small parts in N.A. for SRAM IGHs has been an issue for some time. Are you saying Harris has a stash of unadvertised SRAM IGH parts?

With an IGH, wouldn't that misalign the sun and planet gears?

Best,
tcs

brakemeister

I think there is some wiggle room

I am sure that HArris has lots of parts which are not on their website....


thor

neilfein

Harris Cyclery told me that "SRAM sells their shifters complete from the clickbox to the shifter".

I've asked my local shop to order the cable guide, retaining bolt, no-turn washer, and plastic cable guide, and asked them to get doubles if the parts aren't that expensive. They're also ordering a chain pull.

My next folding bike will not be a Dahon, and it will use more standard parts. Unless IGHs get more popular by then.

randya

SRAM technical manuals and parts numbers are available on the internet, I just ordered parts and rebuilt a 2001 SRAM SpectroP5 IGH using info I downloaded from the SRAM web site.

https://www.sram.com/en/service/sram/tech_manuals.php
https://www.sram.com/_media/techdocs/..._T3_8_2005.pdf

Dahon.Steve

Internal hubs all suffer from these problems. It's just something you have to live with for the pleasure of using them. I learned to buy extra axel nuts and washers before they become a problem. They are not that expensive but they do wear out from constant changing of the rear wheel due to flats. That's why I use Marathons and a rear Tuffy tire liners to prevent getting flats and using up the nuts.

neilfein

Steve, where did you buy the extra nuts from? I know what I need to get (SRAM has a spare parts manual that's well-labeled with exploded views of the hub assembly) but my local shop is having trouble getting ther parts. Harrisis looking into this, but it sounds like they can't order individual parts.

This has been going on for some time, and I'm getting more and more disenchanted with Dahon.

Bruce, the T3 axle nut is a 10.5mm part. Does that mean I need a 10.5mm chain pull?

BruceMetras

I'd still use the 10mm axle tug and ream it out a little if needs be .. I have an older Sachs hub here with 10.5mm axle and the one 10mm axle tug I have is a tight fit .. a dremel would size it in a hurry..

10.5mm nut is a bit of an odd ball .. it's 10.5mm x 26TPI ... if it were me, I'd get a couple of Sturmey nuts (10.3 x 26TPI) and see how they fit your already somewhat worn axle.. might be a little tight, but tight might be good.. if you can't find the correct nut (10.5mm x 26TPI) in the US, you can always go UK .. many sites have them listed .. such as This One..

invisiblehand

Randya, recently mentioned that SRAM has a reputation for failing to supply components for the IGHs and supplied a link. From the Bike Friday Yak, SRAM DD parts are difficult to source other than through Bike Friday.

I doubt that this is a Dahon problem rather than an SRAM problem. Although Dahon presumably has some leverage in this area.

invisiblehand

A dremel might be too powerful. Kind of like using a flame thrower to kill a roach.

Since we are only talking about a half mm here, just find an old reamer and widen the hole a bit. I used what that linked website called a tapered reamer (non-precision) with my Surly Tuggnut.

neilfein

Bikeparts.com emailed me back - they have a T3 hub parts kit!

https://www.bikeparts.com/search_resu...p?ID=BPC353867

I placed the order, I hope it'll be here soon.

neilfein

Here's what's going on: The Bikeparts order is on the way. However, in the meantime, Dahon responded to an email I had sent asking them where I could order the parts I needed. My bike shop was also able to find the parts. the shop says the bike'll be ready Friday, and I'll have spares.