Front hub in rear?

AceofSpades

AceofSpades

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I really want to use my stock 18" rear wheel, but would like to eliminate the drum brake. I would like to lace in a hub from a front wheel and utilize the front brake rotor and caliper...

Will the front hub and axle hold up to use on the rear? Anyone ever lace this set up?? If it would work, Ineed to find a 36 spoke hub from a 75 with High Shouldered rims... anyone?
 
Only way to use a 18 inch with a front hub that I know of: Buys Omars or Jim Henry's adapter. Sent the hub to Buchanans and have it laced to a 18 inch wheel they sell with the width you want. It will be expensive, but the best way to go.
 
If you decide to go with the wheel adapter kit, the bearings included in kit will accept the stock 20 mm axle, and by the time you get all those spacer adaptors and extra fancy alluminum parts all bolted up , the flux capaciter on the bike will then be fully activated, and as soon as you hit 88 MPH you will instantly be transported the exact year your bike was made... citys and towns will be smaller and todays suburbs will still be corn fields... Have Fun and be safe, and watch for cows in weird places.
 
I'm using a stock 19" front on the rear with one of Omar's kits. I made my own right-side spacers and an adapter to fit a non-stock rear brake. Now, I'm planning to take the hub and do just as racerdave also suggests, and send it to Buchanan's with an 18" rim I already have, for custom spokes and lacing.

My Brembo caliper needs the spoke clearance that the narrow hub provides, at least with the hanger I'm using; otherwise, I'd be all for a wider hub from the get-go.

In retrospect, I'd suggest going just about any other route. Between the time and expense of Omar's kit, the additional custom machining, and off-brand brake, I would have been better off with a Sportster hub or a Barnes-type QC, and benefit from a better spoke angle/stiffer wheel.

Having said that, I haven't had any trouble with the set-up at all, and if the wheel is flexing, I'm not noticing. The brake is awesome, and the wheel is crazy-light compared to stock.
 
Hmmmm these are not the answers I was hoping for, LOL.... thanks to all, but this is why I asked, I knew someone out there has tried it.... I wan a disc rear brake mainly because I am (GASP) not running a front brake on this build. SAVE THE LECTURES AND WARNINGS, I KNOW. I must find a cheaper, but effective way to keep my rim and have a disc brake... please keep the advice coming.
 
If you go Harley keep in mind that metric and imperial don't get along. I think newer Harleys might use metric sized axles but older ones didn't so you can't use a bearing swap to match those to the metric axle of the XS. If the hub's bearings are for a much larger axle you could keep them and neck in the custom spacers you'll be making to take up the gap.
 
racerdave said:
derm, what year etc Sportster hub would you use? What about sprocket a and disc/caliper alignment?
Click to expand...

I didn't go this way myself (I didn't know better at the time), but user AAV_Yardape posted this inspirational shot in another thread:

rearhub.jpg


It's a 2002 Sportster hub, 3/4" axle, mounted in a Radian swingarm which had been modified to fit the axle (the axle/fasteners in the pic are temporary for mock-up only). Notwithstanding the axle/swingarm issues, everything about this looks like a better starting point to me than the XS front hub; stronger, lighter, wider spoke base, and a wider bearing base. Looks like plenty of room between the hub and the swingarm for a caliper hanger.

From what little research I've done, these HD hubs are easily available across many model years, and at a reasonable price. Richard Pollock at Mule has himself suggested these several times as a superior alternative to the XS front hub.

All the solutions are rife with compromise... XS front hub/Omar's kit is straight-forward and proven, but heavy (compared to some others) and obviously not as ultimately strong (although probably good enough for most street-ridden bikes). Sportster hubs, vintage Barnes-type, or other QC hubs have obvious design and strength advantages, but with a little more expense and complication in set-up. Then you could just go with any number of billet aftermarket MX or speedway solutions, but burn $500+ on a bare hub even before the brakes/rim/spokes get sorted!

I've looked longingly at various billet MX wheels, ISR hubs, etc., and balking at the $500-$1500 price of admission, chose to go with the proven Omar's kit (with my own changes, of course). Honestly, why worry about ultimate strength and light weight? If those factors were the greatest priority, we'd all be riding new modern bikes... For me, style, originality, and an honest invocation of "vintage feel" trumped strength and weight...

But here's the reality check, the dirty total nobody wants to admit to:

Stock '73 TX750 front wheel: $100
Omar's conversion kit: $295
Ducati caliper: $85
Aprilia hanger: $40
Ducati rear master cylinder: $35
Custom rotor adapter: $525 (I bartered labor for that one, so it wasn't out-of-pocket)
Russell brake line: $45
Brake pads: $10
Avon tire: $90
Banjo brake switch: $20
Brake rotor: $65

Let's add in $20 for all new fasteners, but not count the two other hangers and calipers bought for fitting/development purposes, but ultimately not used... My complete rear wheel/brake is already over $1300, not including my own time!

Suddenly, those seemingly "too expensive" alternatives don't sound so ridiculous after all, and while I shopped around for the best deals whenever/wherever possible, I wasn't saving any money; I was spending it! :banghead:

Still, it's hard to put a cash value on the pride of accomplishment and satisfaction of doing it yourself. :thumbsup:
 
Derm,I remember that thread, and asked you to see if you had other idea's. What is the actual width gained by that hub only in the spoke mounting area vs a xs front hub? Omars adapter use's the bearing in the original hub location. Jim Henry also makes a adapter for the front hub. I'm pretty sure in e-mails from him, he told me with his adapters, the bearings mount in the adapters. If that is correct, the bearing's are spaced out wider, similar to the above Sportster hub. Might be worth looking into?
 
racerdave said:
Derm,I remember that thread, and asked you to see if you had other idea's. What is the actual width gained by that hub only in the spoke mounting area vs a xs front hub? Omars adapter use's the bearing in the original hub location. Jim Henry also makes a adapter for the front hub. I'm pretty sure in e-mails from him, he told me with his adapters, the bearings mount in the adapters. If that is correct, the bearing's are spaced out wider, similar to the above Sportster hub. Might be worth looking into?
Click to expand...

Omar's kit uses the bearings in the original locations, plus an additional third bearing on the drive-side (the two bearings are "stacked" together). I'm not familiar with the Jim Henry adapter by name, but I've seen a few other homebrew adapters where the bearing is held outboard, and yes, I reckon this is an advantage.

These kits are essentially making the front hub wide enough to fit the swingarm, and providing attachment for a sprocket. Some use a stock sprocket, while others (like Omar's) use custom sprockets with a 6x80mm BCD disc brake bolt pattern.

The brake caliper is the limiting factor when it comes to widening the spoke base. The only practical ways to get around this are to make the rotor larger (more spoke clearance closer to the rim), move the caliper as far outboard as possible (the rotor can only move out so far, and there must be room for a caliper hanger besides), or to use a slimmer caliper.

The Brembo 2- and 4-piston calipers are fixed, with piston(s) on both sides of the rotor. I think they look better, and have less moving parts, but they are "fatter" than single piston calipers like the stock late-model XS or many modern rear Nissin calipers. Consider, for example, this (ugly) early mock-up of mine:

2011-12-11_11-30-03_11.jpg


I have honestly considered cutting the hub in half, and widening it from the inside-out; pushing both the bearings and spoke flanges outboard. There's no issues at all on the drive-side, but it gets crowded on the brake side. Modern MX hubs push the straight-pull spoke heads right out into (typically) integrated rotor mounts, but there's still only so far outboard they can go until the spokes hit the caliper. Note too that many modern swingarms are wider, perhaps for just this reason.

In my case, with my current caliper/hanger combo, I don't suppose I could push the spoke base more than 5/16" to the right. I could make a new lower-profile caliper hanger, which might gain me another 3/16". That's 1/2" outboard each side. If I cut the hub and widened it by 1" in the middle, I'd still need outboard spacers/adapters to preserve correct chain alignment and mount the rotor. Also, the high and narrow hub flanges would now be subject to further stress by the greater spoke angle.

The whole exercise becomes one of robbing Peter to pay Paul; some slight gain in one area at the expense of compromise in others, not to mention another round of time and expense! I think these front hub/rear disc kits are great, but trying to get the XS front hub to go further than that is likely to lead down a frustrating dead-end road.

I've obviously over-thought all of this. From the very beginning of my build, I set for myself a careful and deliberate design limitation: Notwithstanding safety and/or reliability, I would work to preserve an overall "vintage feel", and eschew overtly modern materials, surface finishes, or modifications. Such a limitation precludes modern billet hubs.

Taken item-by-item, many parts of the bike are obviously and thoroughly modern, but taken as a whole, most observers (even gear-heads who I assume would know better) are caught out by the illusion and wonder aloud what year my presumably restored/stock bike is. Having succeeded at that, I don't lose sleep over otherwise sub-optimum rear hub geometry. :laugh:
 
For anyone that's done the "Front Hub in the Rear" conversion... I'd be very interested to see how you mounted the rear brake master cylinder and incorporated it with the rear brake pedal.

A picture would be fantastic. Thanks

PhiloMcGiffin
 
I should have been more clear.... I am building a hardtail frame, so clearances can be adjusted..I just want a rear disc brake with my 36 spoke Akront high shooulder "rain-catcher" 18inch rear wheel....b and I don't want to spend a small fortune to do it......
 
AceofSpades said:
I should have been more clear.... I am building a hardtail frame, so clearances can be adjusted..I just want a rear disc brake with my 36 spoke Akront high shooulder "rain-catcher" 18inch rear wheel....b and I don't want to spend a small fortune to do it......
Click to expand...

Sorry, I think we kinda high-jacked your thread... :doh:

The most straight-forward way to get where you want is to lace a front hub to a rear 18" rim, and use Omar's (or another) conversion kit to mount a stock rear XS disc brake. With that as a starting point, you can make further brake modifications down the road if/when you decide they're necessary.

If you have the front hub and rear rim, you're ahead on that count, but the spokes will be custom (figure around $100 for bare spokes from Buchanans). Omar's kit is $295 with bearings. You should be able to pick up a stock rotor, caliper, and hanger pretty reasonably, especially on this forum. It's entirely possible to lace your own wheel and save yourself some money there (although personally I'd pay for pro wheelbuilding).

All said and done you'll probably be up around $500, and for that you'll have a a less-than ideal wheel/brake (but probably good enough). If, after a few rounds of "improvements", you end up with a $750+ rear wheel, you may, like myself, wonder why you didn't start with a better/more expensive build from the very start, and not be dealing with the compromises.

Long story short: A 36-spoke high-shoulder 18" rear disc wheel using stock XS parts is a tough one, neither impossible nor cheap. If that's really what you're set on, then charge ahead (Lord knows, I'm right with you!), but don't expect it to be an easy road.
 
Well, I plan on going to a little known Japanese bike parts yard not too far away, see what he may have there... I do appreciate the advice so far....... unless I find a suitable rear hub, I guess I will stick with the drum rear for now.....
 
osteoderm said:
I didn't go this way myself (I didn't know better at the time), but user AAV_Yardape posted this inspirational shot in another thread:

rearhub.jpg


It's a 2002 Sportster hub, 3/4" axle, mounted in a Radian swingarm which had been modified to fit the axle (the axle/fasteners in the pic are temporary for mock-up only). Notwithstanding the axle/swingarm issues, everything about this looks like a better starting point to me than the XS front hub; stronger, lighter, wider spoke base, and a wider bearing base. Looks like plenty of room between the hub and the swingarm for a caliper hanger.

From what little research I've done, these HD hubs are easily available across many model years, and at a reasonable price. Richard Pollock at Mule has himself suggested these several times as a superior alternative to the XS front hub.

All the solutions are rife with compromise... XS front hub/Omar's kit is straight-forward and proven, but heavy (compared to some others) and obviously not as ultimately strong (although probably good enough for most street-ridden bikes). Sportster hubs, vintage Barnes-type, or other QC hubs have obvious design and strength advantages, but with a little more expense and complication in set-up. Then you could just go with any number of billet aftermarket MX or speedway solutions, but burn $500+ on a bare hub even before the brakes/rim/spokes get sorted!

I've looked longingly at various billet MX wheels, ISR hubs, etc., and balking at the $500-$1500 price of admission, chose to go with the proven Omar's kit (with my own changes, of course). Honestly, why worry about ultimate strength and light weight? If those factors were the greatest priority, we'd all be riding new modern bikes... For me, style, originality, and an honest invocation of "vintage feel" trumped strength and weight...

But here's the reality check, the dirty total nobody wants to admit to:

Stock '73 TX750 front wheel: $100
Omar's conversion kit: $295
Ducati caliper: $85
Aprilia hanger: $40
Ducati rear master cylinder: $35
Custom rotor adapter: $525 (I bartered labor for that one, so it wasn't out-of-pocket)
Russell brake line: $45
Brake pads: $10
Avon tire: $90
Banjo brake switch: $20
Brake rotor: $65

Let's add in $20 for all new fasteners, but not count the two other hangers and calipers bought for fitting/development purposes, but ultimately not used... My complete rear wheel/brake is already over $1300, not including my own time!

Suddenly, those seemingly "too expensive" alternatives don't sound so ridiculous after all, and while I shopped around for the best deals whenever/wherever possible, I wasn't saving any money; I was spending it! :banghead:

Still, it's hard to put a cash value on the pride of accomplishment and satisfaction of doing it yourself. :thumbsup:
Click to expand...

True, having gone down that road many times you will begin to know a quicker , faster and cheaper way of doing it. As I have :thumbsup:
 
builder said:
True, having gone down that road many times you will begin to know a quicker , faster and cheaper way of doing it. As I have :thumbsup:
Click to expand...

Well, notwithstanding all the (excellent) points I made in this thread over a year ago, I went ahead and built this anyway:

2013-03-26%2017.04.23.jpg


2013-03-26%2016.52.36.jpg


I haven't built the rest of the wheel to fit around this hub, but I'll keep y'all posted...
 

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