Another 'Pulstar rear hub 7 speed bearing' drama

[dongward]

I picked up a pair of these very nice Pulstar wheels off a fellow RB'er. The rear hub was a little crunchy so I thought perhaps over tightened cones. Upon a little further inspection it turns out the bearing seal to the drive side is a starfish as opposed to a nice smooth round surface! :facepalm:

As if to add injury to this, I also discovered the freehub won't take an 8 speed cassette and isn't Shimano compatible...

At best I can source a part to get them back up and running but only in 7 Speed mode which isn't any use so I think I might have to move them on - there was an issue with 8 speed hubs rubbing the actual hub body and in the top image you can see where this has occured with even a 7 speed cassette. I've read the Bikepedia entry and searched the RB archive etc so know the limitations/previous issues. It seems strange too that such a cool hub has such a crappy heavy axle and cones/nuts...?





What's the deal - do I replace the part and sell these on or can I redeem something for the build? :?

Donnie

 

[dongward]

Anyone?

 

[KermitGKona88]

Re:

Can you not just fit a Shimano 8sp cassette body ?????

 

[dongward]

Re: Re:

Can you not just fit a Shimano 8sp cassette body ?????

I wish. They were non shimano compatible and I think the free hub is actually glued in to the hub :shock: I don't think there is a simple answer outside of '7 speed only'... But I do need a spare hub/bearing race to fix it and sell it on. Nice wheels but dubious design.

 

[KermitGKona88]

Re:

This is where Pulstar correctly sees the rear hub market going. This hub is the combination of American thinking, with some Asian parts. The hub shell is CNC machined of a single piece of billet aluminum, in a highly complex bit of work. The shell is drilled through to reduce weight, and bored on the non-drive side to reduce weight. At the drive side the hole is tapped with 22mm by 1mm thread pitch threads. These threads are for the Taiwan made screw-in freehub mechanism. The freehub is easy to remove using a 10mm hex wrench inserted in the end of the freehub and turned counter-clockwise. Unlike the Shimano 10mm hex bolt which comes out as a separate piece, the whole freehub mechanism is removed with this model. The freehub uses a set of nine 6.35mm diameter steel ball bearings to carry the outer load. A rubber seal at the outside of the freehub reads "KT", "SEALED", "T W N R O C", "17298". This leads us to believe the entire freehub mechanism is made in Taiwan by "KT", unfortunately the freehub isn't sealed in any conventional way that a term like "sealed" would infer, on an aftermarket replacement cassette hub. A low quality steel axle is used, with a matching low quality steel cone race, and inexpensive chrome locknuts. The quality of work on these parts leads us to believe that they arrived with the freehub from the orient. A Korean KBC 6000D precision sealed bearing cartridge is pressed into the non-drive side. The non- drive bearing is covered by a machined aluminum cap held inplace another of the inexpensive chromed locknuts. Our guess is this hub is a good candidate for direct from the orient importation. (we have learned that Pulstar intends to change the chrome lock nuts to Black, look for the KT label on the freehub). As for the cassette to use with this freehub. We tried Shimano's new XT spider type, the CS-M737 and found the spider holding the sprockets together came in direct contact with the hub shell. Though it will revolve, the spider will grind against the shell wearing it away, until you tighten it so it will wear the shell down further, all the while inducing friction and drag. We also tried the Shimano HG-90 and the HG70-8 speed cassette sets, and found about the same results. In this case, there are three rivets which hold the largest 6 cogs together as a unit. These rivets protrude slightly a both ends, and Shimano freehub bodies and everyone elses takes this into account. The Pulstar "KT" freehub however, allows the rivets in contact with the hub shell, scoring it. This grinding was even worse than the M737 cassette. The only way to get an HG-90 or HG-70 to work decently, yet imperfectly, would be to use a grinder to remove the three rivets. The Pulstar Cassette rear has a 53.8mm hub flange diameter, with the flanges spaced 54mm apart. The Cassette rear spoke holes have a 47mm center circle diameter. This hub is available only in a 32 spoke hole drilling only. It comes in a 135mm axle length for 8 speed mountain use. The hub shell is anodized in Blue, Black, Grey, Lavender, or Silver. The weight of a 32 hole Pulstar Cassette rear is 410 grams. To work on the hub you will need a 17mm box wrench to loosen the locknut while using a 15mm cone wrench to hold then loosen the machined aluminum axle cap. The axle has an internal shoulder, striking it from the drive side pushes out the non-drive bearing, a 10mm wrench removes the freehub body. NO LONGER AVAILABLE

 

[integerspin]

Not like this freehub is it?

 

[dongward]

Not like this freehub is it?

Hmmmm, not sure - I sincerely think the freehub cannot be removed without destroying the hub so I'm guessing no... Although it does suggest in the above description that they can be removed - I must go investigate!