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-   -   is it OK to have rear der. not shift to smallest cog? (https://www.bikeforums.net/classic-vintage/897074-ok-have-rear-der-not-shift-smallest-cog.html)

cptsilver 06-21-13 12:42 PM

is it OK to have rear der. not shift to smallest cog?
 
Another minor issue from my Schwinn Passage build:

I was able to squeeze the new 126mm wheelset into the 120mm frame, which is actually about 123mm, so getting wheel into the dropouts was quite easy. I installed a new 7-speed FW which sits very close to the frame. As I got my chain on yesterday, what I feared became reality, the chain was rubbing against the seat stay on the smallest cog.

Is it OK to adjust the RR so that it just doesn't shift to the smallest cog? I'm willing to give up that gear as I expect I won't be using it that often. Or do I need to get a 6-speed FW? Are those more narrow?

Thanks.

cyclotoine 06-21-13 12:54 PM

there is no reason why you can't just not use that cog and set the limit so that it doesn't shift into it.

RaleighSport 06-21-13 12:54 PM

Yes, but you'll probably want to know that you can respace the axel in the hub or replace it with a longer one, but that should usually also mean you'd need to redish the wheel as well. Others will be along who do this sort of thing to give you more info.

cptsilver 06-21-13 12:57 PM


Originally Posted by RaleighSport (Post 15768307)
Yes, but you'll probably want to know that you can respace the axel in the hub or replace it with a longer one, but that should usually also mean you'd need to redish the wheel as well. Others will be along who do this sort of thing to give you more info.

That would mean re-lacing the wheel, right? Sounds like a lot of work :)

JAG410 06-21-13 01:03 PM

Nah, you can move spacers about and re-dish the wheel with a spoke wrench. Or most LBS's should do this for about $20.

cyclotoine 06-21-13 01:16 PM


Originally Posted by JAG410 (Post 15768334)
Nah, you can move spacers about and re-dish the wheel with a spoke wrench. Or most LBS's should do this for about $20.

In that case, it would be cheaper to buy a new shimano 6 speed HG freewheel which retail for about $15.

blamester 06-21-13 01:28 PM

If you are happy with the ratios why muck about with it?
Are your shifters indexed?

ThermionicScott 06-21-13 01:34 PM

It would bug me -- I'd add a washer and redish or get a 6-speed freewheel.

Pars 06-21-13 02:00 PM

It might be tight, but couldn't you add a 1mm washer on each side, and not redish?

Lascauxcaveman 06-21-13 02:01 PM


Originally Posted by JAG410 (Post 15768334)
Nah, you can move spacers about and re-dish the wheel with a spoke wrench.

I like this. And re-dishing part may not be needed.

This is the type of project a noob can figure out on his own, once set in that direction, thereby leading him down the slippery slope of C&V DIY perdition. Bwahahahaha!

I'd take the wheel to my LBS, not to have them do the job, but to ask them if they would sell me some old spacers to make it work. The time I actually did this, they gave them to me for free. (It didn't hurt that I bought a tube, patch kit, tire levers and a mini-pump from them earlier that week :) It's the kind of older LBS that has little boxes of stuff like this on hand, in case they ever have to work on older bikes.

cyclotoine 06-21-13 02:26 PM


Originally Posted by Lascauxcaveman (Post 15768556)
I like this. And re-dishing part may not be needed.

This is the type of project a noob can figure out on his own, once set in that direction, thereby leading him down the slippery slope of C&V DIY perdition. Bwahahahaha!

I'd take the wheel to my LBS, not to have them do the job, but to ask them if they would sell me some old spacers to make it work. The time I actually did this, they gave them to me for free. (It didn't hurt that I bought a tube, patch kit, tire levers and a mini-pump from them earlier that week :) It's the kind of older LBS that has little boxes of stuff like this on hand, in case they ever have to work on older bikes.

True he could go this route, but unless he must have 7 speeds, which I don't think he does, this is certainly a more complicated solution to a very simple problem. Therefore, the cheepest, least time consuming and best option it to put a 6 speed freewheel on (yes it is narrower). There are several reasons.

1. The frame is 123mm and adding more space will make it harder to install the wheel and at that point I would recommend coldsetting and drop-out alignment, which costs more money, changes the frame more permanently.
2. Adding even 2 mm gets into replace the axle territory since there is probably only 4mm showing on each side. 3mm is getting pretty short.
3. The more dish the weaker the wheel, old rims aren't as strong as modern rims.

People will tell you they , have done it, it works fine, etc etc.. it's fun it's a learning experience. And I agree with that, but the fact remains that in order or simplicity and cost effectiveness you options are as follows:

1. Adjust the limit screw so the derailleur doesn't use the smallest cog, ride and be happy.
2. Put on a 6 speed freewheel.
3. See how much extra room you need. maybe 1-1.5mm will do it and add that to the drive side. Readjust your cones for equal axle sticking out on each side, redish the wheel and ride way.. might be 127 or 127.5 not, a little tougher to slip in, but should be okay. Might consider coldsetting
4. Add equal amounts of spacer to both sides so you do not need to re-dish and keep the wheel integrity as high as possible, possibly (likely) replace the axle with a longer one and cold set the frame and re-align the dropouts.

3/4 are kind of a toss up. I placed 3 before 4 because you might get away with just 1 extra mm and no cold-setting.

cptsilver 06-21-13 02:39 PM


Originally Posted by cyclotoine (Post 15768643)
True he could go this route, but unless he must have 7 speeds, which I don't think he does, this is certainly a more complicated solution to a very simple problem. Therefore, the cheepest, least time consuming and best option it to put a 6 speed freewheel on (yes it is narrower). There are several reasons.

1. The frame is 123mm and adding more space will make it harder to install the wheel and at that point I would recommend coldsetting and drop-out alignment, which costs more money, changes the frame more permanently.
2. Adding even 2 mm gets into replace the axle territory since there is probably only 4mm showing on each side. 3mm is getting pretty short.
3. The more dish the weaker the wheel, old rims aren't as strong as modern rims.

People will tell you they , have done it, it works fine, etc etc.. it's fun it's a learning experience. And I agree with that, but the fact remains that in order or simplicity and cost effectiveness you options are as follows:

1. Adjust the limit screw so the derailleur doesn't use the smallest cog, ride and be happy.
2. Put on a 6 speed freewheel.
3. See how much extra room you need. maybe 1-1.5mm will do it and add that to the drive side. Readjust your cones for equal axle sticking out on each side, redish the wheel and ride way.. might be 127 or 127.5 not, a little tougher to slip in, but should be okay. Might consider coldsetting
4. Add equal amounts of spacer to both sides so you do not need to re-dish and keep the wheel integrity as high as possible, possibly (likely) replace the axle with a longer one and cold set the frame and re-align the dropouts.

3/4 are kind of a toss up. I placed 3 before 4 because you might get away with just 1 extra mm and no cold-setting.

Considering that I'm lazy, and probably won't miss the smallest cog, I'll just set the limit screw for now. Perhaps I'll get a 6-speed FW later.

Thanks all! Great help everyone!

dddd 06-21-13 07:04 PM

I've put an Ultra-6 freewheel on a Campag 5sp hub and literally used a 1/2 millimeter spacer under the driveside locknut to achieve the needed clearance. It also helps to use a narrower chain, and I've even used a Dremel to clearance the end of a protruding seatstay for a 14t cog.

oldskoolwrench 06-21-13 07:31 PM


Originally Posted by Lascauxcaveman (Post 15768556)
I like this. And re-dishing part may not be needed.

This is the type of project a noob can figure out on his own, once set in that direction, thereby leading him down the slippery slope of C&V DIY perdition. Bwahahahaha!

I'd take the wheel to my LBS, not to have them do the job, but to ask them if they would sell me some old spacers to make it work. The time I actually did this, they gave them to me for free. (It didn't hurt that I bought a tube, patch kit, tire levers and a mini-pump from them earlier that week :) It's the kind of older LBS that has little boxes of stuff like this on hand, in case they ever have to work on older bikes.

+1

It's an easy fix, and you're lucky;the freewheel probably hasn't threaded extra firm enough to need two boys and a man to wrench it off! :p

Use cyclotoine's idea; just put a 1mm keyed washer under the outer locknut and re-adjust the hub, then thread the FW back on. A touch of elbow grease to drop the wheel in, and voila!

Here's some classic bike mechanic porn for inspiration...


:thumb:

jimmuller 06-21-13 08:18 PM

First question - do you ever use a gear that high? Of course it depends on your crank. I found I never used it with a 52T ring. So if you want to set the RD not to go there, then just do it.

But then you'll think of other bothersome aesthetics, or at least things that would bother me. Why carry the weight if you can't use it? If you're not using it, why not just go with a 120mm hub (5-speed or Suntour Ultra-6) anyway? You give up one gear, making your gears further apart than they would otherwise if you had 6 gears to cover the same range instead of 5. Things like that.

Just add a spacer to the axle and re-dish the wheel. It's easy, but it does take time.

zukahn1 06-21-13 09:23 PM

No you wouldn't need to replace the wheel but respacing and dishing the wheel to work with all gears can be pretty tricky and is a lot of work. Peronelly if your just using the bike as a occasional rider I would just tune out the low gear which is perfectly fine the gearing will be about the same as original or what you would get with a 6speed. It is basicaly a choice of turning a stop screw a couple of times on the RD, 2hrs maybe more work respacing and dishing a wheel or spending $30 on 6speed freewheel.


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