I bought a bunch of bolts to replace my rusty ones which look like they’re about to give up. Think they were M5. They’re way too thin and short – what should I be buying please? I feel so old and out of touch!

Different stems use different size bolts, there’s really no way to know other than to take out the old ones and measure (or find someone else who’s done it with your stem)

what should I be buying please?

Something to measure your old bolts with before you buy new ones?

Ta. Was kind of hoping there was a standard size… Will actually have to get off the sofa and have a proper look.

Or just buy a selection of M4/M5/M6 stainless steel bolts. They come in handy for plenty of bits on the bike.

CraigW- that’s exactly what I’ve done 😃

If you need bigger than M5 then it’ll be M6.

Then just measure the shank length and order the ones you need off ebay.

Just use duck tape. It will be fine.

Remember to post up pictures of your x-rays.

If not M5 they’re M6, usually a mix of about 15mm and 20mm lengths. Some people including mbuk stupidly call M5 bolts M4 because they use a 4mm Allen key, M6 bolts usually use 5mm allen key. The M is the thread size not the allen key size. So if your using a 5mm allen key its most likely m6.