Where's the dumb questions thread?


#2861

This all might be moot though, apparently Grin Tech doesn’t have a torque sensing BB in the 73mm shell / 120mm spindle combo that I need.
They said they only stock 68mm and 84mm width.

I’m a BB idiot, can you easily put a 84mm in a 73mm shell?


#2862

Do they have it in a different spindle length? An 84mm BB has a 11mm wider BB insert, so you would have a minimal thread interface. You’d be better off cutting 2.5mm off each side of your 73mm BB and putting a 68 in there, which is still stupid. Can you use a different torque/cadence sensor, such as a crank or pedal based power meter? Otherwise, buy a fatbike frame with an 84mm BB in there and go for it.

I’d just call them or send them an email explaining what you’re trying to do, because I bet they have a good hack for it.


#2863

Yeah, I could use one of the external sensors, I just liked the idea of having it all hidden away in the BB shell and having the pressure/rotation speed settings to nerd out on. External sensors also seem to be very open to the environmental exposure considering they are in the splash zone.

I’ve been emailing with their sales guy but all his replies have been brief with minimal suggestions.


#2864

The more you spend on Shimano hybrid cranks, the more true the rings get. All of those cranks have riveted together chainrings, which might be fine for your cargo bike (and for $30), but if you want a higher quality crank, vintage mountain stuff is cheap and often has the same or similar gearing. Finding 170 can sometimes be tricky, though.


#2865

interested to hear how you go. torque sensing is so rare on kits, my PAS setup is fine for getting groceries up the hill, but it would ride much better if it was proportional to rider input.


#2866

[quote=Andrew_Squirrel]This all might be moot though, apparently Grin Tech doesn’t have a torque sensing BB in the 73mm shell / 120mm spindle combo that I need.
They said they only stock 68mm and 84mm width.

I’m a BB idiot, can you easily put a 84mm in a 73mm shell?[/quote]
No that’s for fatbike crap, and you don’t want 5mm of spacers on each side

You can probably get away with using the 68mm BB plain, and just accepting a few mm of ds crank offset (and/or not having a lockring on the NDS)

at the very worst you cut your shell down 2mm per side and re-face to 68mm, but that’s unlikely


#2867

[quote=JUGE FREDD]
at the very worst you cut your shell down 2mm per side and re-face to 68mm, but that’s unlikely[/quote]

I wonder if Cyclefab / Haulin Colin would do that?
Seems like it wouldn’t be worth all that effort and cost though.


#2868

It’s not.


#2869

What’s the current best fender flap material for DIY? I remember Andrew Squirrel finding some good stuff months ago, about which I already asked him to remind me but I guess I didn’t write it down anywhere. We should just put something about this in the tarck product database.


#2870

my preference is whatever discarded ABS filth prophylactic you can find in a co op bin. Reasoning is that unlike Mrs Butterworth bottles it is somewhat engineered to live outside. But yeah ill start a thing on the spreadsheet for this.


#2871

I used vinyl stair tread stuff from Home Depot on the recommendation of some random internet bike person. It works ok and I now have enough for an entire fleet of bikes.


#2872

FTFM


#2873

You’re in NYC? If you’re anywhere near South Queens/North Brooklyn, I’ll give you a big chunk of stair tread (cash value: $0.30) to try.


#2874

Yeah, its Lowe’s that has the stair tread for something like $2.99 for a huge piece in black or brown.
https://www.lowes.com/pd/M-D-Stair-Treads/3056225
https://www.lowes.com/pd/M-D-Stair-Treads/3056223

I’m also testing out plastic folder material from some office supply store, I think Jimmy recommended that once.
Nothing I’ve tried so far has been perfect. Everything rips and breaks at some point so its hard to say what works the best.
The one flap that seemed to be holding up the best used a faux leather material made by a local person but that finally ripped last week so I replaced it with a stair-tread duplicate I had made a long time ago.

My friend Peter apparently has some pretty good material he picked up recently, good reminder I should grab a piece for testing.


#2875

Yeah, I really don’t want to deal with that, especially after this email from Grin:

[quote]
Hey Andrew, there are no other suppliers of the TDCM BBs and you can’t get them from TDCM either anymore as they decided to discontinue this product. They told us this in January of this year when we were in discussions about paying for a custom tooled 73mm option.

At the moment, the only option for 73mm BB shells is to shave off a few mm from either side of your BB cup using a BB facing tool and then fit it with a 68mm sensor.

If you don’t want to do that, then for now yeah unfortunately basic PAS it is. We’re working to see if we can get Sempu to do a custom run of 73mm BBs for us, but can’t give any timeline since it’s still more of an if than a when. [/quote]


#2876

Yeah, I really don’t want to deal with that, especially after this email from Grin:

[quote]
Hey Andrew, there are no other suppliers of the TDCM BBs and you can’t get them from TDCM either anymore as they decided to discontinue this product. They told us this in January of this year when we were in discussions about paying for a custom tooled 73mm option.

At the moment, the only option for 73mm BB shells is to shave off a few mm from either side of your BB cup using a BB facing tool and then fit it with a 68mm sensor.

If you don’t want to do that, then for now yeah unfortunately basic PAS it is. We’re working to see if we can get Sempu to do a custom run of 73mm BBs for us, but can’t give any timeline since it’s still more of an if than a when. [/quote][/quote]

I wonder if most ebike manufacturers are moving to the Bosch mid-drive motors with a built in torque sensors. I guess that makes more sense than having susceptible sensors and wires in tiny bottom bracket shells.


#2877

tbh the clear plastic box cover to some trp spyres have been great fender flaps, even if they look like a museum of gore RN


#2878

Can i use a downtube shifter to control a dropper post? I’m thinking there’s no reason why not.


#2879

depends on what cable pull it needs, and it won’t have a spring return like a normal dropper lever has. worth a shot though

RE: mudflaps – i used some clear purple plastic folder material last winter. Worked well, but tore off pretty easily. Not very durable when you put a hole in it with no grommet


#2880

What are you putting this on?