TallRider

I just helped a friend buy a used road bike - a Trek bonded-aluminum 1100 from the early '90's with 7-speed RX100 drivetrain. Fewer than 1,000 miles, and the chain isn't much worn, but is pretty dirty. So I want to take it off and clean it. I've got an old Shimano Hyperglide connector-pin, for 8-speed HG chains. Will this also work to reconnect the 7-speed chain? Thanks.

schang

Considering Shimano seems to sell 7/8-speed replacement pins as the same thing (see Performance: https://www.performancebike.com/shop/...6&srccode=2047) I think you are probably safe.

HillRider

I think the first "narrow" chains intended for 7-speed freewheels/cassettes became the "8-speed chain" when 8-speed components were developed so the chains are identical.

genericbikedude

They are all 3/32" until you get into 9 speed. I would bet $5 that most people couldn't tell the difference between an all HG chain, and one that was made from new scraps of IG, HG, SRAM, and off-brand 3/32" chain.

HillRider

They are all 3/32" even for 9 and 10-speed. The 3/32" dimension is the inner plate spacing and is common to all derailleur chains. What varies from 7/8 to 9 to 10-speed chain is the OUTER width and, consequently, the overall pin length and plate thickness.

TallRider

Yup, I'm specifically wondering about the outside width. I know that modern 7/8 speed chains are the same (and they work on 6 and 5, too, because the inside width is all 3/32") but I'm not sure that when chains for 7-speed originally came out, they were just as narrow as 8-speed chains.

I've tried semi-cleaning the chain with ProLink and a rag, and it's done a pretty good job, but I think I may as well take it off and clean it, and hope that spare pin works. It looks as if it will, bu may be a touch to narrow for the chain.

7-speed cogs are spaced at 5.0mm, while 8-speed cogs are spaced at 4.8mm.

operator

If all else fails you could pick up a new sram pc48 7/8 speed chain from probikekit for around $9 shipped.

TallRider

Yeah, Performance is actually based here in my town, and my backup plan is to pick up a PC-48 for ~$12 if the Shimano HG "narrow" doesn't go back together. When I measured the outside-plate width of the chain in question, it looked to be about 6.8mm, while a SRAM 8-speed chain (that I'm running on two of my bikes) seems about 6.3mm. But the SRAM chains are new, and the Shimano is older, and the plates work a bit wider apart over time.

TallRider

Okay, the pin fits, and the "HG narrow" chain seems to be the same width as the 8-speed standard chains.

Grand Bois

I have a Superglide 7 speed chain that came with this kit:

https://tinyurl.com/q6z2e

It's definitely wider than a PC-48, although it's marked "narrow". I can't give measurements because the battery in my digital caliper is dead.

roccobike

Hey Tim, Hope your doing well. With regard to the chain width, I know I'm not as knowledgable as the other posters here. I recently had cause to look into this issue because I just purchased another road bike that has a IG chain on a 7 speed Shimano set-up. The same IG Shimano chain was original equipment on my 8 speed Specialized Rockhopper. According to Sheldon Brown, IG cassettes are contoured on both sides and require a slightly wider chain. IG chains will work on both HG and IG cassettes. But HG chains will only work on HG cassettes. Hence the HG chain has the term 'narrow' on the outer link.