T47 shell width help

[ltwiens38]

I'm a big guy (6'8"x230lbs) and run long cranks on my bikes (215mm.) I have a pair of 130bcd Andel cranks with a 24mm spindle along with the corresponding external cup bearings that fit into a standard 68mm BSA shell. In my experience, those bearings last half a year at best and I'm wondering about an alternative. As with most bike related things for big guys, bigger is better (tube size, spoke count, etc) so, I figure T47 is the obvious choice. Except, from what I can tell, if I want to re-use my Andel cranks, I will still use external cup bearings in the T47 shell. I'd like to get away from external cup bearings - The way I see it, bringing the bearing inside the shell will make it stronger: I rarely have to change the bearings on my super long ISIS or square taper cranks.

My question is: If I go to an wider T47 shell and use an inboard bearing, will that be that same as a 68mm t47 shell and external cup bearing? I'm not quite clear on the exact width I need - will 87.5mm work or do I need an 89mm shell?

Or perhaps the external cup/68mm T47 setup is already a lot better than my current external cup/68mm BSA setup? If that's the case then I'll just go to that.

I hope this all makes sense.

Thanks,

Lyle Wiens

[Eric Estlund]

Outside of cup size, for the BB's you are looking at are the bearings themselves different? Either race or ball/ roller size?

[ltwiens38]

Outside of cup size, for the BB's you are looking at are the bearings themselves different? Either race or ball/ roller size?

I don't understand the question.

Lyle Wiens

[ltwiens38]

Maybe what I'm trying to do isn't even possible. I can't find anyone on here that has.

Lyle Wiens

[ltwiens38]

Okay, well maybe I asked for help too soon: From the Wheels Mfg website I discovered that I can use a 86.5mm bb and an internal bearing to give me a 91.5mm over bearing width which is roughly the same as an external cup in a 68mm bb that has a 90.8mm over bearing width. Problem solved.

Thanks everyone! ;)

Lyle Wiens

[EnginCycles]

The system works as follows. For a 24mm straight spindle (as in not 24/22 GXP) the bearings are either external for 68mm or internal for 86.5mm and with that system the bearings will be the same. For 73mm it is the 91.5mm if internal. There is not a road 30mm internal option (or SRAM MTB) which is why DUB came to be. If you want a stronger bearing White Industries took advantage of the larger shell with the external bearings and makes a Heavy Duty version of the BB. It might not be a listed item as it might not have made it past being an idea. I believe they still have them. Call them and ask for the HD version of the bottom bracket.