ISIS BB Upgrade

[comish83]

Currently riding a Trek 1200 with an ISIS BB about 150 miles a week. Sadly it is a triple and I wanted to make it a double. I cannot find a double crank compatible with an ISIS BB. Any thoughts? Can I just ditch the BB and change it to a BB30?

[bikinchris]

Originally Posted by comish83

Currently riding a Trek 1200 with an ISIS BB about 150 miles a week. Sadly it is a triple and I wanted to make it a double. I cannot find a double crank compatible with an ISIS BB. Any thoughts? Can I just ditch the BB and change it to a BB30?

A BB30 is a pressed in system. I didn't know that there was a Trek 1200 with a BB30 bottom bracket, let alone an ISIS bottom bracket that is compatible with BB30.

There are/were double chainring ISIS compatible cranks. You might find a good one used. (edit) I just checked ebay and there were about 10 on the first page with a search. Most were compact gearing. Is that what you are looking for?

But I think it would be easier for you to swap out for a crankset with an outboard bearing, like most current systems use.

[oldpotatoe]

Originally Posted by comish83

Currently riding a Trek 1200 with an ISIS BB about 150 miles a week. Sadly it is a triple and I wanted to make it a double. I cannot find a double crank compatible with an ISIS BB. Any thoughts? Can I just ditch the BB and change it to a BB30?

The ISIS BB for a double has a shorter spindle than for the triple. ISIS BBs for doubles are still 'out there', as are ISIS cranksets for double BUT this system was crappy and I recommend a shimano crank and BB 'system' that will thread into your english threaded BB w/o issue..and it won't cost much..go see a decent LBS and talk to them.

Your BB shell is threaded and the specs-68mm wide and 1.37by 24..BB30 is a 42mm diameter 'system', without threads..a system not compatible with your frame and no advantage anyway.

[bart998]

You require a bb with a shorter spindle and removal of the inner chain ring... unless the rings you have are oddly sized.

[Mark McM]

Originally Posted by bart998

You require a bb with a shorter spindle and removal of the inner chain ring... unless the rings you have are oddly sized.

Ditto this. The ISIS system uses standardized BB lengths - 108 mm, 113 mm and 118 mm. The 5mm increments were picked to correspond with the ~5 mm chainring spacing, and 5 mm difference between standard rear hub widths (130 mm & 135 mm). If you remove the inner chainring and get the next shorter BB, the remaining chainline will be re-aligned for standard double chainring alignment.

[comish83]

Originally Posted by Mark McM

Ditto this. The ISIS system uses standardized BB lengths - 108 mm, 113 mm and 118 mm. The 5mm increments were picked to correspond with the ~5 mm chainring spacing, and 5 mm difference between standard rear hub widths (130 mm & 135 mm). If you remove the inner chainring and get the next shorter BB, the remaining chainline will be re-aligned for standard double chainring alignment.

Thank you all for the advice! Debating on just upgrading to a newer bike with a carbon frame versus pouring money into the 2005 trek 1200. I would think the 2005 Trek 1200 aluminum frame wouldn't be that far behind current carbon frame weights? Components could use a serious upgrade though...

http://bikepedia.com/QuickBike/BikeS...rek&model=1200

[oliver1850]

There are some ISIS road doubles out there: TruVativ Elita, Bontrager Race, and Origin8 come to mind. I realize there's sometimes a stigma attached to riding a triple but I'd recommend leaving it alone until either the rings or BB need replacing. At that point I'd follow OldPotato's advice and put a Tiagra or 105 crank with outboard cups on it.

[El Chaba]

The ISIS system got a bad rap because the axle size -when crammed inside a BB shell-allowed for little room for the bearings and they were often not up to the task and wore quickly. Of course the other half of the equation was that most of the bearings were poor quality Chinese examples. It's pretty amazing how durable an ISIS BB can be when some additional design effort is made and quality materials are used. Two examples come to mind...There is an SKF made unit that uses roller bearings...They are pretty tough to kill.....the other example is made by Stronglight...It uses double row bearings and is available with either titanium or steel axles. I have one of these on my Time that I have had since 2004. By this time I have no clue as to how many thousands of completely trouble free miles the BB has on it. Pretty good for a system with a reputation for a short life. I have never been able to get anywhere near that kind of mileage out of a CAMPY UT set of bearings...

[54ny77]

Haven't we defeated ISIS?

Oh wait, wrong forum...

[fiamme red]

Originally Posted by oliver1850

I realize there's sometimes a stigma attached to riding a triple but I'd recommend leaving it alone until either the rings or BB need replacing.

I agree.