Least shimano had the decency to use same cranks.
AFAIK Pinarello are still BSA 68? and it’s Team Sky with their marginal gains that are pushing that? (could be wrong).
I’ve crossed several bikes off my shortlist due to stupid pressfit solutions. I’ll only go to pressfit when they are a fit once and last the lifeftime of the bike, and not a consumable like they are now. At least one mfr on here has confirmed they’re sticking with BSA 68/73.Posted 4 years agomikewsmithSubscriber
From Santa Cruz, purveyors of common sense
Why does this frame use a standard thread-in bottom bracket, when many of your competitors use press-in style (BB30, Pressfit 30, BB90, BB92, BB86)
It is true that there are some slight weight savings available with the various pressfit bb designs (exact weight savings obviously vary depending on system, frame manufacturing techniques, and crank model), but we don’t feel this small savings make up for the inconveniences. We are still able to make a frame that is lighter than most of our competitors, while still using a heavier bb system. There are a number of disadvantages that exist with press fit systems:
1) Special installation and removal tools are required for these parts, including a headset press. This is not convenient for most home mechanics, and they are quite expensive. Traditional external BB’s can be installed or removed with a simple $10 hand tool.
2) “Permanently installed cups”. Shimano doesn’t recommend removing and re-installing their press in bb cups (as they may become damaged), so moving parts from bike to bike is no longer an option. http://techdocs.shimano.com/media/techdocs/content/cycle/SI/SI_0053A_001…
3) Creaking or shifting bb’s can be common with these systems. Since the bearing is pressed into a cup, which is then pressed into the frame- it can be hard to get all of the press fits snug- without being too tight on the bearing or too loose in the frame.
4) Reasonable tube sizes. One of the most commonly claimed advantages of a larger bb shell is the larger diameter downtube that goes with it. This may be an advantage on road bikes, where tubes can be incredibly thin and large for optimal stiffness. On a mountain bike, this area of the frame sees a lot of abuse from rocks and crashing, and needs to have a certain amount of wall thickness to survive actual use. Using what we consider a “safe” wall thickness and carbon layup, and a fairly typical tube diameter, we get an exceedingly stiff, light, durable product. If we used a larger downtube, we would either have a heavier frame (same wall thickness but larger diameter), or a less durable product (thinner walls and larger diameter).
5) Chain clearance. Take a look at some of our competitors frames with press in bb shells. The down tube comes so close to the chainrings that many frames have chainsuck guards on the downtube! In our mind, the chain should be able to fall off on a mountain bike and not get jammed between your crank and thin-walled carbon downtube.
6) Backwards compatibility: Many of our customers purchase a frame and build it up with their choice of parts, or parts from an old bike. By using a standard bb, we are compatible with everything without requiring confusing adaptors.
7) Chainguide compatibility: While it may seem strange to talk about putting chainguides on a short travel bike, it is becoming more common now with 10 speed drivetrains. Thread in bb’s mean the frame is compatible with bb mount chainguides. We like versatility….Posted 4 years agomikewsmithSubscriber
aye, just a pity they blotted their record by helping spearhead 27.5 eh?
Yep they were right there in the cheer leader outfit….
SANTA CRUZ (Mike Ferrentino, whose comments were presumably vetted by suspension engineer Joe Graney, who is on the record as not looking forward to 650B): First, i do not entirely agree with (the premise that the industry is driving this). I think consumers are a big part of this interest bubble right now. According to francis at MTBR, “650b” is the second most popular search term on their site at the moment, and the 650b forum traffic is showing huge growth. It is valid to argue that the industry is at fault for even beginning to entertain the idea of 650b wheels, but consumers are clamoring right now for what they perceive to be the next better mousetrap. Another thing to consider – IF this takes off, does anyone realize how much crow the industry is going to have to eat listening to grant petersen saying “I told you so?”
650B wheel size comparison with 26 inch and 29er mountain bike tires installed
Comparison from another angle. See below for tire models.
I think on the consumer side there is a desire for some sort of better mousetrap/magic bullet – a wheel size between 26? and 29? that will combine all the positive attributes of both into one bike that will do everything. That desire is a bit naive, but people go down that road all the time.Posted 4 years ago
Yep they were right there in the cheer leader outfit….
They may not have been getting jiggy with the pom poms but they definitely had their marketing hats on. The bronson was pretty much the poster boy/bike for 650 – well it seemed to be here, dunno how it played out in the USPosted 4 years agojamesoSubscriber
I can’t see many reasons not to spec BSA, well maybe BB92 in some cases but only if the design needs it. HT2 MTB bearings may be a bit poor durability-wise but the fitting system is sound.
One thing often overlooked with PF/BB30 among all the stiffer BB/crank and bigger downtube requirement claims is that the shell is still 68mm wide, so the bearings may be bigger but being internal (rather than HT2’s external cups) they’re closer to the centre line of the bike so the leverage on them from pedal forces will be higher. How much difference that makes I’m not sure but it’s not an improvement. BB386 scores better there but isn’t much use on MTBs, though 1x chainsets could overcome a lot of that.Posted 4 years agoandytherocketeerSubscriber
About the only positive I can see for most of the formats is for mass produced BSO’s. Machining a straight tube is fractionally cheaper, and making the bike is a case of stick 2 bearings in and ram them home with a hydraulic press.
BB30 seemed like a nice idea at the time, but surely machining all the grooves is more costly than machining a thread.
BB386 – does anyone even use it? got the impression it was *yet another* format frame that just allows every crank format to fit with adapters.
Pressfit don’t make any sense in my book until the BB shell cannot be made any wider, and the bearings are as far from the center line as is possible, and are robust and sealed enough to never need replacing (but possibly with a way of just ramming fresh grease in).
My old cup/cone from 1989 is still going strong. If pressfit matches that, I’ll swap.Posted 4 years ago
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