Bottom bracket upgrade question: PRESS-FIT system size 86.5 X 41

[Erik_A]

I have a Basso carbon cyclocross frame that needs a crankset upgrade. *The original crankset is a Miche "EVO Max" with 24mm bearings on both sides. *Basso said that the frame is compatible with "BB 72 SHIMANO or any other brand with PRESS-FIT system size 86.5 X 41 - axle diameter 24mm".

Would I need to extract the original cups out of the frame and install a new BB? *Since Shimano also uses 24mm bearings on both sides, would any Hollowtech II crankset work, or would it need to be specific for Pressfit?

I am really only used to BSA threaded bottom brackets. Thanks in advance!

[echappist]

I have a Basso carbon cyclocross frame that needs a crankset upgrade. *The original crankset is a Miche "EVO Max" with 24mm bearings on both sides. *Basso said that the frame is compatible with "BB 72 SHIMANO or any other brand with PRESS-FIT system size 86.5 X 41 - axle diameter 24mm".

Would I need to extract the original cups out of the frame and install a new BB? *Since Shimano also uses 24mm bearings on both sides, would any Hollowtech II crankset work, or would it need to be specific for Pressfit?

I am really only used to BSA threaded bottom brackets. Thanks in advance!

Hollowtech and any non-30 mm Rotor would work.

The bearings are located in cups that are pressed into the BB shell, alas the "pressfit" moniker. One usually doesn't need to take out the bearing cups to swap cranksets, and assuming your old BB bearings are smooth, they should work with the new crankset.

If you do want to install new BB cups (either the 7241 mentioned in your post or Dura Ace level 9241 (https://bike.shimano.com/en-EU/product/component/duraace-r9100/SM-BB92-41B.html)would work), you will most likely need to use an extractor tool and a rubber mallet to knock the old BB cups out of the BB shell (e.g. this one from Shimano (https://www.backcountry.com/shimano-tl-bb13-press-fit-bottom-bracket-removal-tool?CMP_SKU=SHIU17C&MER=0406&skid=SHIU17C-BLA-ONESIZ&mr:trackingCode=30A9A6F1-9471-E911-810C-005056944E17&mr:referralID=NA&mr:device=c&mr:adType=online&iv_=__iv_p_1_g_107755199001_c_447974403081_w_pla-58379999688_n_u_d_c_v__l__t__r__x__y_7811_f_online _o_SHIU17C-BLA-ONESIZ_z_US_i_en_j_58379999688_s__e__h_9018943_ii_ _vi__&CMP_ID=PLA_GOc001&utm_source=Google&utm_medium=PLA&k_clickid=_k_EAIaIQobChMIpOypjrX_6gIVC9vACh2OKwwpE AQYASABEgLsm_D_BwE_k_&gclid=EAIaIQobChMIpOypjrX_6gIVC9vACh2OKwwpEAQYASAB EgLsm_D_BwE))

I personally hate effing pressfits. Nothing but trouble... Could just be that I'm neurotic, but I wince when I literally have to use brute force to smack the bearing cups out of the shell

ETA: Park Tool makes a more elegant removal tool (https://www.biketiresdirect.com/product/park-tool-bbt-903-pressfit-bottom-bracket-bearing-tool-set?adl=1&gclid=EAIaIQobChMIpOypjrX_6gIVC9vACh2OKwwpEAQYBCAB EgJUi_D_BwE). Fewer pieces to misplace, and cheaper, too

[Erik_A]

Wow - Thanks echappist ! I appreciate the advice!

[Erik_A]

I tried to install a Shimano Hollowtech II double crank. If I tighten until there is no lateral play, than the crank arms rub the edge of the press-fit BB shell. Would a spacer of some kind between the bearings and the crank arms work? Maybe something like the spacer that comes with Shimano Hollowtech II triple crank, though that might be too thick. Any ideas?

[nublar]

Yes you generally need a spacer on each side:
https://www.jensonusa.com/Shimano-Hollowtech-II-BB-Spacer-1

[Erik_A]

Thanks very much. I assume a 0.7mm spacer on both sides.

[dddd]

I add spacers only as needed, and usually only on the left side, for best/smallest chainline.
Usually this would be but a thin shim.
Usually a shim/spacer is used just so that the left arm locator pin can fall into the 4mm hole in the spindle.

Clearance issues would seem not to be frame specific, since the bb "cup" flange stands proud of the shell. :confused:
At least that's how today's buildup of a Chapter 2 Huru Team Edition with 9100 cranks went. No shims, no rub and I can see a sliver of daylight between the left arm and the cup flange.
The real fun was getting the 6800 front derailer to play nice with the 11s SRAM Red shifters!
https://live.staticflickr.com/65535/50186515248_b9d856c4b2_c.jpg

[Erik_A]

Would a thinner spacer or dust seal like this help:


Wheels Manufacturing 24mm BB Spacer Pack

https://www.amazon.com/Wheels-Manufacturing-24mm-Spacer-Pack/dp/B07N4CSRS8/ref=redir_mobile_desktop?ie=UTF8&%2AVersion%2A=1&%2Aentries%2A=0

https://images-na.ssl-images-amazon.com/images/I/51YGd7yrKeL._AC_SL1000_.jpg

[echappist]

Sorry, just realized you posted a follow-up question.

I was under the impression that spacers are not needed on road cranksets. I have swapped Rotor and Shimano cranksets btwn three different frames, each using a BB from a different manufacturer (Rotor, Shimano, and Token, IIRC), and I never needed to use a spacer.

I also have a road pressfit BB on a MTB (should have just bought a MTB BB online, but the shop insisted that a road BB would work), and I did end up needing to use spacers on the left side, as suggested above.

I'd be more hesitant about usage of spacers, unless if you are running a wider crankset on a road frame

I tried to install a Shimano Hollowtech II double crank. If I tighten until there is no lateral play, than the crank arms rub the edge of the press-fit BB shell. Would a spacer of some kind between the bearings and the crank arms work? Maybe something like the spacer that comes with Shimano Hollowtech II triple crank, though that might be too thick. Any ideas?

Make sure you are following the instructions provided by Shimano. The following normally works for me (without using spacers), basically follows what Park Tool suggest (https://www.parktool.com/blog/repair-help/crank-removal-and-installation-two-piece-compression-slotted)s

-Insert DS part of crankset into BB, and wrap chain around a chainring (I usually wrap it around the small chainring).
-Attach NDS crank arm to the spindle. You'll know that the crank arm is in the right position when you can toggle the stop plate (see image below from Park, which shows the stop plate in the open position) to the closed position.
-Hand tighten the spindle cap. This merely sets the preload. DO NOT tighten this one as far as you can. There's a tool for this (or, alternatively, back of a large table spoon might just work)
-Use a 5 mm allen key to iteratively tighten the top and bottom pinch bolts

https://www.parktool.com/assets/img/repairhelp/Figure_7-14.jpg

[Erik_A]

I figured it out! I needed a wave washer on the non drive side between the BB cup and the bearing. That pushed the bearing out so that it was the correct width. No spacer was needed.