I need your help. I have a Zipp Vumaquad crankset on my current frame. I am considering buying a new frame which would come with Pressfit 86.5 standard. There is no bottom bracket available from Zipp which allows the use of Vumaquads on a Pressfit 86.5 frame.
I have found some old threads
which recommend bearings/adapters from Rotor and THM Carbones.
While I found one comment which said the Rotor 4130 bearings did not work, there is no confirmation that the THM adapter works, or does not work. Any experience out there, please? PLEASE !!!
Rotor 4130 (the name says what the above combination requires: an outside diameter (OD) of 41mm and an inner diameter (ID) of 30mm to accommodate the 30mm spindle)
Tune Smart Foot PressFit BB92 & BB86 Kit MTB + Road (these use the THM bearings, apparently)
BOR ROAD Bearing Kit BB86
I saw in that other thread someone saying they couldn't get it to work and that they thought the crank axle wasn't long enough and was leading to the crank binding (side-loading the bearings) when tightened. I guess I don't see why that should be the case since the crank is compatible with italian 70mm shells with the same thickness external BB cups as with a 68mm. When running the Italian setup you leave out two 1mm spacers that you use on the BSA. Anyway, point being that the crank seems to have an extra 2mm of room to play with... compared to a BSA or BB86 setup.
I think the issue might be more with the length of the axle, I tried fitting my Vuma Quads to a frame with a BB386evo bottom bracket, the vuma axle was too short, resulting in binding when trying to tighten the crank bolt up enough, I even took out all the spacers and that did not work.
It might work if I took out the bearing seals, but that would leave the bearings completely exposed.
i am trying (or was going to try) to fit vumaquads to a Pressfit 86.5 bottom bracket. if i understand correctly, BB386evo shell width is 86.5, same goes for Pressfit 86.5, only difference is the shell diameter (BB386evo = 46, Pressfit 86.5 = 41). so, if you say the axle is too short for BB386evo, this has to be true for Pressfit 86.5 too...lannes wrote:Are you trying to fit vumaquads to a frame with a bb386evo bottom bracket ?
If you are it doesn't work, I've tried it the quads axle is too short.
This might help with the frame bb standards
http://problemsolversbike.com/files/tec ... erence.pdf
the vumaquad spindle is 101mm long. but i do not know if that includes the part of the spindle that inserts into the crank arms though. reading through the links below, i would say it includes the part that inserts into the crank arm (see this pic, which shows the BB90 shell = 90mm with bearings sticking out 2mm on each side = 4mm)
zipp vumaquad + BB90 part 1
zipp vumaquad + BB90 part 2
Alright... This doesn't bring me any further (even though their reply came quickly; that's what I call customer support!)...
I havent looked in awhile, but if memory serves, THM had a 41mmx30mm BB that may be narrow enough.
the rotor bearings are the cheapest solution (approx. EUR 40.-) but that won't help if those are to wide...
the BOR bearings should be 11mm wide ("special bearings 30x41x11") but i do not know how much of those 11mm stand out of the frame, and how much is inside... on the other hand, BOR also states on their website "Special BB30/BB905 in 30x41*x7"
THM bearings are 11mm wide, THM confirmed this to me.
Perhaps the problem could be solved with headset bearings like these 41x30.2x6.5 probably need to use two either side to prevent early failure with such small bearings and perhaps a internal plastic spacer to prevent inward bearing creep? http://www.chainreactioncycles.com/cane ... -prod11266
so, i would guess if there are Pressfit 86 bearings which flush-fit into the BB shell (not sticking out of the BB shell, i mean), then i think it would work. don't you think so?
i don't know, i am no engineer with only limited understanding of technology , but maybe with a machined tube in the correct length? my assumption would be based on the fact that there are no elevations inside the BB shell. in the case of Pressfit 86.5 the BB shell is 86.5mm wide. with an assumed 10mm of bearing width on each side, the tube would have to be 66.5mm long... then no "lip" would stand out of the BB shell... no?lannes wrote:+1 on machinenoise's post - Without some sort of bearing cup lip, how would they stay in place, the rotor 4130 lip looks to be around 1.5-2mm
but i begin to think that it would be better/easier to buy a THM Clavicula/Clavicula M3/Storck Powerarms crankset instead. those do work and there is no DIY involved...
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