What size bolts for lower rack eyelets?
 

I have a 2007 Specialized Allez, which has rear rack eyelets. The mounting holes at the top of the seatstays have bolts in them, but the bottom ones (near the deraileur) only have rubber plug inserts. The bolts from the top of the seatstays do not fit in the bottom eyelets, they are a little too big. I also tried using the water bottle mounting bolts, and they too are too big. Can anyone tell me what size they'd be?

The rear rack I have only came with extra bolts which fit the mounting holes at the top of the seatstays.

Thanks,

Scott

Almost all bikes made in the last quarter century use M5 (5 x .8 mm) bolts for that, same as for bottle cages. My guess is that your frame's eyelets may need to have a tap run through them to clear the paint that's blocking the threads.

Sheldon "#10-32 Is Very Close" Brown

Thanks for the reply - you are correct. There was paint in the eyelets, and I was able to very carefully apply some more pressure and run the M5 bolts through them without stripping anything (other than the unwanted paint).

My commute this week will be more comfortable without having to carry a backpack now. Much appreciated.

Scott

This is why I love the internet. People helping people 10 years ago provided the answer I needed to install a rack onto my wife's bike. Like the original poster, the 5mm bolts seemed to large. But 4mm were too small. Standard sizes were no better. I could not find a 4.5mm, so I resorted to a more intensive search and found this thread. I cautiously followed ZPL's advice and had the same results.

Thanks to ZPL, Sheldon, and Bikeforums for providing this space, and not removing older content! Long live online forums!!

Some exceptions to M5x0.8, are some 1980's Giant and some 1980's Giant made Schwinn branded bikes which have M6x1.0 threads.

Indeed. It's fun to see a thread that Sheldon contributed to. He left us too soon the year after the OP posted this thread.

Very cool. It was neat to be reminded of this thread. Glad it was helpful sceva!

Wow, even after being here as long as I have, I've never seen an actual Sheldon post. I honestly wasn't aware he posted here.

oh wow. was gonna say use a thin pocket knife to scrape some paint off the inside threads. he passed away in 2008, (the year I got into cycling). I was lucky enough to work 1 block from a bike shop he had a relationship with. don't remember what the relationship was. but the shop was very down to earth & didn't make fun of my DIY stuff. if you're ever in West Newton, MA drop by Harris Cyclery & buy something. I found them as a source for long stems for older steel bikes, some bike service & some other products

https://www.sheldonbrown.com/harris/

Sheldon used to come by the shop I worked at in Cambridge back in my racing days. He was friend's with our mechanic. I used to hear long discussions of 3-speed fixed gear hubs (they both had them) and other esoteria. That was 1977. Sheldon was already famous, but probably only for a 20 mile radius.

Ben

I liked the bike hacks he made.

For instance, this selectable 37 gear inch freewheel on one side, and a choice of 70 g.i. or 94 g.i fixed gear. Yeah, another 3-speed hub conversion.

From the notes, he wanted to ride it on the D2R2 !!https://www.sheldonbrown.com/bichain/images/bichain.jpg

And this thread still lives on.
RIP Sheldon, and thank you.

July 2022 and this thread is still helping lost souls like me!

Thank you for this info. The bolt from the upper eyelets were too small for the lower eyelets. Took the bolt to Home Depot and confirmed on the testing bench that it was an M5x0.8. Bought a pair of M6x1.0 bolts and they fit perfectly on the lower eyelets. This was on a cheap Nishiki Pueblo mountain bike from Dick's sporting goods (department store bike) that I've converted into an e-bike.