treal512

My current Shimano 6-speed freewheel (14-16-18-20-23-26) is needing replacement and I have my search narrowed down to a SunRace 6-speed 14-28T or a SunRace 7-speed 13-25T. My question is, can my bicycle take the 7-speed freewheel by only adjusting spacers and without having to resort to major adjustments? At the time being, I rarely ever use my 23 or 26T cogs, so the idea of picking up a 28T cog doesn't sound very useful to me. This is why I am wanting to go with the 7-speed.

Also, my downtube shifters are indexed and only have 6 speeds, so I would need to replace them with a 7-speed if I were to switch to the 7-speed freewheel setup. Any recommendations? I don't even know where to start with shifters. As for my chain, I have that narrowed down to a SRAM PC-870, but I'm unsure if I should go with a KMC or a Shimano HG70/90 series chain. Any advice is appreciated. This is all fairly new to me. Thanks.

ultraman6970

You have to measure, no other way to know. Remember suntour fit 8 cogs in a freewheel that fit a 126 mm hub w/o any problems. They just put the cogs closer and made them thinner. W/o knowing the height of the thing you want buy there is no way to know.

treal512

The distance between my dropouts looks to measure exactly 5 inches or 127mm. And here are the two freewheels I am looking at...

6-speed: https://www.amazon.com/Sunrace-Freewh...peed+freewheel
7-speed: https://www.amazon.com/SunRace-7-Spee.../dp/B003RLE9X8

dddd

Looking at that rear axle, I'm 95% certain that a 7-speed will have room to spare.

Measure the thickness between the outside face of the small cog and the inside face of the droupout:
You'll only need 4mm at most to have clearance for a 7-8-speed chain, so it looks the 2-3mm-wider 7-speed freewheel will have that clearance if the clearance I'm seeing is more than 6mm with the 6-speed freewheel on there.

There is sometimes an issue with the larger diameter of a 14t cog allowing the chain to contact the seatstay where it starts bulging in, but this one, again, looks pretty generous to me.

And don't forget that all Uniglide, Hyperglide, Accushift, Perfect, (basically all of the Aasian freewheels made to this day), will work and shift at their best using 9s chain, which would add another margin of clearance in marginal cases. And if a 9-speed chain will work with your chainrings, it will also have generous clearances inside of the front derailer cage, for almost no shift trim required ever.

Wheels Of Steel

Shimano chains technically won't accommodate a quick link. For this reason I prefer SRAM chains. They're only making two at this point, the PC-830 and PC-850. You can't go wrong with either.

treal512

Just to make sure on the measurement, are you referring to this space (image)? If so, it measures 0.25in or 6.35mm. Is that black piece removable though?

Also, as for the 9-speed chain, would you then not recommend this chain? https://www.amazon.com/SRAM-P-Link-Bi...ds=SRAM+PC-870

dddd

Yep, that's the gap.

And your SRAM is a decently-narrow 7.1mm width, so a very safe bet for your chainrings and cogs.

Now to find a 7s shifter, you only need the right one.

What's the black piece? You mean the locknut or possibly some bit protruding from tyhe derailer's B-tension plate?

I'ts also never a problem to add a very thin washer to the driveside axle spacer stack in order to grab an extra millimeter of clearance, without having to worry about re-dishing the wheel. Any more than that and the brake pads may be wanting for subtle adjustments, but you'll still never feel any difference while riding.

Wheels Of Steel

When is Amazon expected to purchase Trek?

treal512

Oh man, only replacing one DT shifter would drive me bananas. I'm willing to buy a set. I don't really know my right hand from left (models, hierarchy, etc) when it comes to DT shifters though. I've been reading up on freewheels for hours. Here are 2 quick finds on the shifters though. My current 6-speed shifters are Light Action. Are Shimano 105s good or better? What should I set my sights on?

https://www.ebay.com/itm/SHIMANO-BRAZ...item2a358a90ff
https://www.ebay.com/itm/Shimano-Ligh...item2330b34931

And the black piece is I dunno? It's on both sides between the spacers and freewheel, so I figured it was not removable. Maybe I'm just not understanding how this spacing will work.

Hmm?

pastorbobnlnh 

Why does your freewheel need to be replaced? Have you considered servicing and cleaning it and the chain instead?

Also given that you rarely use the 23T and the 26T cogs another option might be to eliminate the 23T and switch things around and regear to something like 14-16-18-19-20-26 or 14-15-17-18-20-26. This way you gain more of the gears you'd use--- and preserve the 26 for the bailout times it is really needed.

Just my two cents. This way you've not replaced something which might not be worn out and continue to use the same shifters.

Phil_gretz

Switch your shifters to friction mode and run the 7-speed. Keep the 28T as there will no doubt come a time when you will wish that you had it. You didn't tell us what your front chainring configuration was. Is this a triple or a double chainring? If you have a 52-42 double, having only a 26T rear yields pretty difficult climbing gears, unless you're strong and in terrific condition...

So, what's wrong with your current freewheel again?

kunsunoke 

Also worth considering -
https://www.amazon.com/Shimano-MF-TZ2...peed+freewheel
https://www.amazon.com/Shimano-MF-HG37-Tourney-Freewheel-13-28T/dp/B001IORDH0/ref=sr_1_1?ie=UTF8&qid=1389276914&sr=8-1&keywords=Shimano+13+28+freewheel
https://www.amazon.com/KMC-X8-93-Chai...s=kmc+x8+chain

The KMC chain is profiled for indexing, and has a nice master link included as part of the overall package.

Your existing shifters may have a hidden extra click, in which case they will work with the seven-speed freewheel in index mode. The only way to know for sure is to install the new freewheel and chain, then test. If the indexing doesn't work, or you only end up with six clicks, you have the option of installing a six-speed ramped freewheel or upgrading to 7-speed index shifters.

I'm currently using KMC chains exclusively on all of my recent builds. They can be had at a fraction of the price of Shimano HG chains, and they don't require use of proprietary installation pins.

SJX426 

Went from this:


To the equivalent of this:

Wheels Of Steel

We've had a few issues with KMC chains of late where I work. You get what you pay for I reckon.

ThermionicScott 

I have to quibble with this a little. SRAM still makes the nicer-looking PC-870 and 890, and the 830 is inferior to the other three with its non-hardened pins. I would avoid anything lower than the 850 if you ride more than a few miles per year.

kunsunoke 

What issues did you have with the KMC chains?

Do the chains suddenly snap, or something?

And are we talking about KMC's HG-compatible chains or some other chain they make for lower-end applications?

Not trying to bust chops here - I have a few of the 8.X series chains on my bikes, and they've been working pretty well, so if there's a problem I can head-off I'd just as soon do so - thx

zukahn1 

A lot of good advice so far. You should be able to run a 6/7 speed you would likely only need to add a single spacer for a 7s, yet there is a good chance you may not need to, the wheel looks like it may have already been respaced for 6/7s at some point. Bang for your buck your best otions are to buy a 6speed freewheel and keep the stuff you have. Or buy a 7speed freewheel and a good used single Shiminao SIS/Friction 7speed shifter or set there actually pretty cheap, I have one that is a pretty good match for the Op's light action that I would sell at a good price PM me if your interested. The 6speed would be cheaper and easier and 7speed setup would be nice that the OP would basically pick up 2more usefull gears which is always nice. I would much rather have one or two more usefull gears than needed than struggle with having too few few gears or not enough range.

zukahn1 

I have noticed that the production quality on KMC chains has come down a bit of late. They still seem to be fine no real issues and are fine for the price and the easier to use pin's and master link compared to other similar priced chains are nice.

dddd

KMC's X-series chains have all seemed to me to be very high quality.

Their Z-series chains, OTOH, are very inexpensive, so I bought a bunch of them, the better ones with fully profiled outer plates, but when I measure their stretch wear, they seem to give a quite varied reading when checking different locations along the chain.
I've confirmed this with several Z-series KMC chains, so it's no fluke of quality control or of my measurement.
I would think that this "variation of pitch", which might originate in poorly formed rollers, would be tougher on the wear surfaces of the sprocket teeth, although perhaps this might spread the sprocket wear over a longer span of the faces of the teeth, for better or for worse.
Anyway, I don't encounter this problem with inexpensive Shimano chains in the $16 range, or in any of the X-series KMC chains.

I also avoid buying the cheapest SRAM chains, as some of these have tended to become squeaky after a very short interval following re-lubrication.
It's obviously a metallurgy issue as far as I can tell, and not much of a problem for those that use a heavier lube.


I have long been able to use KMC's Missing Links as connectors for Shimano HG 7-8sp chains, but note that it's only the wider of the two Missing Link models that KMC offers for 7-8sp use which will fit Shimano 7-8sp HG chain. These cost only about $12 for a card of 6 links.
The KMC Missing Link II is the narrower version for SRAM chain and for most Shimano IG chain models, while KMC actually still offers 7-8sp chain in both the 7.1mm and 7.3mm widths.

treal512

FW needs to be replaced because it's been gradually sticking more and more often than not. Plus, I'm ready and excited to give these hyperglided cogs a shot. I've heard a lot of good things about them.

I'd love to have more smaller cogs like in the example you provided, but the availability of FWs are not very plenty. I also do not want to buy an old cluster in case I have to troubleshoot or tend to its possible upkeep. At the time being, my bicycle is my only means of transportation and with university beginning next week, I want to be ready with zero hiccups for the semester. There's nothing more frustrating (I'm sure there is) than when your main set of wheels go out of commission when you have a seemingly endless stream of exams and projects due. So this replacement is more precautionary than anything really. I do plan to keep the old FW and eventually clean it out, but I just don't have the time right now.

Going friction is a good idea, but I've been spoiled by my flawless index shifting Also, I have a double 52/42 in the front. I spoke to one of my friends who I tour with and he reminded me of the hills we hit with loaded rigs. I'm leaning towards the SunRace 7-speed 13-28T FW now. I'm excited that it has a 13T cog!

https://www.amazon.com/SunRace-Freewh...d+freewheel+28

Does SRAM have proprietary installation pins?

There's no way I would buy any of the modern Shimano FWs. They look like expletive! I don't understand their choice in design as MANY people looking for freewheels are looking for them for their vintage bicycle. It just doesn't make any sense to me. I'd even go as far to say that their choice in design is a defilement. Otherwise, I would have pulled for a Shimano FW without thinking twice. What a shame.

Thanks for the pictures. That looks great!

Ahh, decisions!

treal512

Actually, what am I thinking? My current top cog is a 26T. The 13-25T SunRace is only a 1 tooth difference and I fair just fine with my current freewheel.

I wish I had more experience with different gearings. I feel like I'm pissin' in the wind!

dddd

Sram's 8sp chains come with their Powerlink, which is removeable but is a little too narrow to fit a Shimano 8s chain (other that the narrower models of IG chain).

The Sram link comes with their chains, and are also sold separately for about $4 ea.

A 9sp Sram Powerlink does also fit any Shimano 9sp chain however.

ultraman6970

Back in the mid 80s when shimano introduced 105 sc and shimano 600 tricolor, their chains came with quick link. Obviously if you are going to use a 10 speed quick link in a 7 speed chain then you will get problems big time. The thing is to source the right quick link.

As for chain, probably even a 10 speed chain will work just fine with 7 speed.

zukahn1 

Stop over thinking it with the 13-25t and regular shifting you will get basicaly all the gears you had before and likely pick up a usefull gear.

treal512

Yea, you're right. Sent you a PM. I'm going with the 13-25T and SRAM PC-870.