stuart1865

Can anyone tell me if the Suntour Ultra 6 freewheel will work if it is replacing a Suntour Pro Compe 6-speed?

Thanks.

cyccommute 

Shouldn't make a difference. I'd not do it, however. Suntour freewheels are a pain to work with. They either break the freewheel tool or they break the freewheel. And, in my experience, they tend to be very tight on the hub. As much as it pains me to suggest it, Shimano's freewheels are better.

stuart1865

Thanks for that. I have, however, already removed the freewheel without issue. I am looking to change from a 14-26 to a 13-30 or 32 with a Suntour BL derailleur,system, which should manage the size jumps handily. I think that they are pretty similar with 5mm spacing and take a similar chain. So, I was looking for some reassurance from others.

philbob57

the ultra-6 is likely to be narrower than the pro-compe, so you may need to adjust the rder's stops.

thumpism

Once SunTour changed from the 2-prong to the 4-prong remover the chance of inflicting damage decreased. The Ultra 6 allowed you to have six speeds in the space of a conventional freewheel's five so, as suggested above, you might need to tweak the limit screws. I think the ProCompe used 6-speeds in the conventional (wider) spacing but if you don't have indexed shifting it should not matter..

Andrew R Stewart 

SunTour made different freewheels in similar and different cog to cog spacing. From symmetrical cog to cog spacing to spacing that varied across the freewheel's width. Since Ultra 6 started when indexing wasn't a thing it really just refers to a 6 cog freewheel that's nearly as wide as a 5 speed one. It doesn't really signify the cog to cog spaces, just infers they are less then the typical 5 cog freewheel's. IIRC the "ultra" spacing (what ever that actually is between any two cogs) was offered in Pro Comp and Winner grades. The difference being is how the cogs were mated onto the core and how the core was assembled. Pro Comps were usually non adjustable in the bearing preload (excepting those tiny/thin shims) and Winners used a true lock nut and cone bearing adjustment (and I have that tool set, unused for many many years). But Winners were also initially meant to be extremely flexible in what cog to cog spaces could be had, how many cogs could be mounted. In addition IIRC Winners came in a few different core designs, cog counts up to 7 or 8 were possible with later cores.

So saying Ultra 6 is like saying your car has a 6 speed gear box. Nothing about a clutch, syncromesh, ratio spread, mechanical or computer controlled.

The most straight forward way to compare freewheels is to hold then against each other or laying flat on a bench top. Then look at whether the total widths match up and/or whether the cogs are lined up between the two units. As SunTour was so willing to make so many versions that used the marketing term "Ultra 6" just reading an ad might not be enough o really tell which arrangement you get. But with friction shifting and a hub with cup and cone bearings a lot of slight mods are easy to make to have a range of reality fit and work. Andy

70sSanO

nesteel 

They're tool interface was arguably better, but the Suntour freewheel will wear forever, and the double click is way cooler than their Shimano counterparts. For the record, dealing with way more freewheels than I care to mention at the coop, I've found Suntour units to be no more trouble than Shimano. The majority of problems removing a Suntour unit stem from improper procedure. Always secure the tool using the quick release skewer. I also much prefer old, vintage, Suntour manufactured remover tools. They're getting tough to find though.

Andrew R Stewart 

+1 on this bolded statement. While I have seen, and had happen to me, cracked bodies of ST branded freewheel tools during challenging removals I have also seen more rounded off Shimano ones (the vice or wrench flats). Phil Atom/Regina tools crack and split along the splines too. So with good technique any removing tool can be fine or not, usually fine. I have a few dozen different FW tools in my box and all are used with good care but all are just a tool. Andy

cyccommute 

Not in my experience. The 4 prong is more likely to cam out of the freewheel even when held in place by an axle nut or quick release. The thinner prongs on the freewheel are also more likely to break.

capnjonny 

One way to make removing a freewheel easy is to clamp the removal tool in a vise. Then you set the wheel over it and rotate the wheel counter clockwise. Works every time. Using the skewer to hold the tool on the freewheel loosely, just rotate the wheel enough to break the bond , then remove the skewer and replace the tool in the vise and spin the wheel off the freewheel.

when I first started , I had a removal tool with 2 fairly thin ears that bent and wore quickly. I purchased (on amazon) a Park removal tool that had much beefier ears. Using the vise and skewer method I have never had a problem since and the bikes we get at the Bike Exchange have often been neglected for decades.

I have a number of Suntour freewheels and they are very robust. For ease of shifting on a non indexed bike a new Shimano hyperglide unit with a new chain and shift cable and cover is the slick trick.

Andrew R Stewart 

Perhaps every time you've removed a ST freewheel. But not for every one including me. Like was said before the lack of securing the 2 or 4 prong tools against the freewheel before applying removal torque can result in "camming out" (I like this term) of the tools dogs from the freewheel's core. Even with good tool purchase against the core some care is needed to keep the forces aligned with the direction needed. Andy (whose broken a few ST tools, a very very few compared to the number of good removals)

SJX426 

https://www.sheldonbrown.com/gloss_sp-ss.html#spacingk7

skillasw

Found this awhile ago from a Suntour technical bulletin, solid info on freewheels right from the source.