# Hussefelt ISIS and Howitzer compatibilty?



## lew242 (Aug 7, 2008)

I have some old Hussefelt cranks and they have an ISIS bottom bracket and ISIS written on the crank-arms. I want to run a burlier system with a guide and my friend has a new set of pimped-out Hussfelt cranks with a Howitzer BB, looks a bomb-proof and it can run a guide with a BB adapter too.

Question is if I buy an aftermarket Howitzer BB will it work with my older Hussfelt ISIS cranks or do I need a new crank-set? 
Also is there a way to make an ISIS crank-set able to take a guide on a frame without tabs? Thanks.


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## slider32 (Apr 7, 2010)

I don't think the cranks are compatable with the howitzer BB.

Yes you can run a guide with the cranks, you need one that mounts "behind" the bb.


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## lew242 (Aug 7, 2008)

> you need one that mounts "behind" the bb.


Not sure what that is? I'm running aggressive AM/FR (6 inch travel). Thanks for the help.


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## mtnbiker72 (Jan 22, 2007)

They will bolt up to the Howitzer BB...but the arms are not offset correctly and you'll have a very wide Q-Factor.

If you want a bombproof ISIS BB, get a SKF from Mtbtandems


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## lew242 (Aug 7, 2008)

Thanks for the information 72. Might just buy new Howitzer cranks as they aren't crazy expensive.


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## Ecogeek (Aug 30, 2009)

lew242 said:


> Not sure what that is? I'm running aggressive AM/FR (6 inch travel). Thanks for the help.


Blackspire stinger is a cheap, good, under BB (or ISCG dep on version), chainguide. Light. And takes a double crank too.

I have a howitzer on order. Same cranks in howitzer. Also have ISIS stuff. Will compare splines on howitzer and ISIS spindles when the H BB arrives (probably tomorrow).

My feeling/expectation, is that the splines on the spindle will be the same. I think Howitzer just uses external bearings for larger balls w higher load-capacity.
BUT, I have not checked yet. I ain't mounting the cranks on there for you, but I will measure the splines w digital caliper and just mate the parts up by hand. That'll be good enough.

There is another thing to consider of course. Chainline. Could be that the spider has different profile on its 'non-drive' side (yeah, I know that's sorta crazy-talk 'non-drive' side of a crankset! You know what I mean. The left side of the mounted cranks), which might mean that the chainrings of the isis set could be hung out farther to the right than they would be with the Howitzer set, even though the splines are the same.
Following me?!
I'll look at it. Soon.

One thing I will say, for AM, you don't need howitzer unless you're really hittin it. If you include the letters A and M in the description, you ain't REALLY hittin it on that bike, as bikes that can really take it, don't go up hills. I ain't dissing. You are probably a stronger rider than me. On my 6' AM rig, I ride GXP Stylos w no problems. I'm 195 fully loaded (inc full face helmet/armour). They have handled minor shore stuff, jumps and drops in the park, real mountain riding. Unless you're old crankset is bust, or you're over 200 and/or really going nuts, then I'd stick w the ISIS stuff until it dies.

The Howitzer and Holz is for the DH rig. 9" travel.


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## Ecogeek (Aug 30, 2009)

OK. Howitzer arrived.

*NOT THE SAME*. Although v close.
The splines are the same height and spacing (so same number obviously). However each spline's x-section profie is different. The ISIS splines have pointier 'tops' (outside edges). The Howitzer have flatter tops.
I took one bb and literally put the end of an ISIS spindle perfectly up against the end of a Howitzer spindle.

What I have not done, is check the inside of the crank-arm 'socket' that mates w the splines for both ISIS and Howitzer. It is still possible, that they are the same.
It is also sure that even if not, with enough force, the ISIS cranks coule be forced onto the Howitzer spindle and would fit super tight. However, you would run various risks. Stripping the crank-bolt, being unable to remove the crank arm and perhaps stripping the spindle threads with a hardened crank-removal tool. If the deformed metal has 'no-where to go', then it cannot be forced on without crushing the spindle slightly (not going to happen), or deforming/cracking the entire end of the crank, which could effectively leave it 'bent' if that plastic deformation is all on one side. Could weaken it greatly or break it during the process.

My ISIS cranks are all on bikes. Otherwise I'd check the internal profile. If that is the same, then despite the differences in the BB splines, the parts will fit together.

That would leave one remaining issue. That mentioned in prev post about chainline and spider profile.

I just mated the howitzer crank with the ISIS bb and they fit 'fine'. I did not tighten.
From eyeballing and feeling, it seems that the howitzer crank is looser than acceptable on ISIS BB (as expected from spline profiles). Which backs up what I said above about ISIS crank being super tight on Howitzer BB.
The metal would deform. Depending on what alloy your cranks are made of. If it's 6061, you could anneal it, and hope that forcing it on work-hardens it again. This is moderately likely. But a super high-risk experiment that I would not encourage. Annealing any part of your cranks is obviously a slightly crazy idea. But hey. Every idea no-one's tried before is a crazy idea. Sometimes they work by luck or judgement or both.
A better idea, which would be a lot of work and also carries a high risk of error, would be to force it on 'slightly', examine where the metal is beginning to deform, then file down and reprofile the inside of the splines on the crank.
This would be a load of work with micro-files. And does not consider that chainline thing.

I think we basically answered your Q.
If you want to be a DIY hero, attempt to do it somehow anyway, if it works and doesn't break, you get the home mech's medal of honor, major props, even though no-one else is likely to follow in your footsteps.

I might be able to 'help' (maybe help you mess up some cranks/break your face) in one last way, Measureing a Howitzer (Holzfeller) single-crank, the mounting surfaces for the chainring (which is in 'middle' position) are 4mm 'higher' from the inner (left as mounted) surface of the spider.
If the middle ring on ISIS is the same distance 'higher', then that solves any pos chainline issues.

Good luck. Def post back.

As in prev reply, I'd use what you have until it dies, ISIS DH BB's are solid. Cheap too. Then get new Howitzer/Howitzer when you can't get new BBs or your cranks are wrecked.
But, keep the old ISIS cranks. When your first Howitzer BB dies, DEF force the old ISIS cranks on there and see if it would have worked.
Bookmark and post back in 2yrs! Lol. 
Whatever you do, think about it. Don't hurt yourself.

Finally. IMO, if you wanted to make this work, the best chance is to check the spider profile. If the mounting surfaces for the middle chainring are about 4mm higher than the inner surface of the spider (around the spline interface), then you could try and go with the reprofiling of the inner splines.
You need a tool that I do not think exists. 
Like a reciprocating dremel (as opposed to rotary).
It would have a tiny file on the end and you'd put that in and file down the spline interface without much effort.
I have 'done this' filed down or 'reprofiled' spline before with perfect success first time. This was to make one BB tool fit another BB. But that job was much easier as the splines I was filing were the external splines so I could just use the rotary tool and diamond disc.

I think it was some shimano tool with a lot of splines too. And I needed to both reduce height and width of all of them. I did not take much care. You can 'standardise' the amount of material removed by just using the same pressure for the same time on each spline surface. Then they all stay v close to the same, without you needing to pay too much attention.

Reciprocating dremel would be a great tool. Maybe it exists. Would be the burglar's favourite unfortunately. Would cause revolution in lock technology!
Most people would apply too much pressure and break the micro files right away. Maybe this prevents sale due to too many warranty claims or too much dissatisfaction from those that don't know what they're doing. Anyway. Enough random speculation. For now. 

Oh. Maybe not. If you had a jig-saw, you could break a micro-file, bolt it in, instead of a blade, and then you have a reciprocating micro-file. Would reciprocate a little too much though. Need a saw that you can control the range of movement and reduce to minimum. Or one that intrinsically uses tiny strokes. Would be v hard to see what you were doing. Would be working by feel and judgement. Doable though. I think I could do it.
Would be possible to make an attachment for a dremel that uses the rotary motion to drive a reciprocating motion into which you could put something like a file or saw. Would not be 'efficient' technically, but practically it would turn your dremel into a micro-reciprocating tool as well as a rotary tool and that would be v 'efficient'.
This probably exists. If not, no patent now! Public domain. It is bound to use an eliptical wheel or a rotary piston. Prob can't patent it anyway. Ancient tech.

Exists 'in a fashion'.
http://www.hobby-worx.com/P20_PTS.htm
83198
$35.


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## lew242 (Aug 7, 2008)

Ecogeek, everything I wanted to know was already explained by Mtnbiker72. I decided that a single speed Stylo GXP would be fine for my purposes. Will upgrade the chain ring and bolts to chrome-alloy later.


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