Bagel Bob

I am just getting back into cycling after 20 years. My favorite bike is a 1989 Trek 1100, (road bike with 3 chain rings, 7 speed cassette, and mid-range Suntour components). I'd like to know if it's feasible to convert the downtube shifters and drop bars to a flat bar and thumb shifters. I have access to tons of old bikes and parts, but not opposed to buying new stuff if there's a good recommendation for this. Mainly, I need to know how to conert the frame mount brazed-on shifter-mount post on the down tube to a cable stay so I could run cables up to the bars.

hokiefyd 

Yes, you can absolutely convert these. You'll need downtube cable stops. If you search for that, you'll see a lot of hits. Here's one example on Amazon. Another option is your local bike shop. They often have small parts bins with tens or hundreds of these things. My bike shop sells stuff like this for $2 each. I understand there are a few different styles of braze-ons (different sizes or something); it may be best to bring your bike in so you can ensure what you might buy will fit correctly.

You can even convert the shifters themselves to thumb shifters with various downtube shifter-to-flat bar adapters. They're not cheap, but they're out there. There are, of course, shifters designed as thumb shifters available as well...both friction and indexed. You have a lot of options from which to choose. Good luck!

Andrew R Stewart 

Yes, done frequently. The key to doing it easily is some details and decisions. Bikes of that era will want what is currently called short cable pull brake levers, compatible with calipers and cantis. The shifters might be indexed but if you choose friction thump levers then there's no compatibility issues. If you want indexed then make sure the new levers match the cog count and you'll need to replace the rear der and the freewheel to what are Shimano compatible versions in that same cog count. Combined shifters and brake levers are pretty common these days but that means there's twice the spec you need to pay attention to. Don't worry about the down tube casing stop. Either it will be compatible (there's that word again) to the bolt on to the boss adaptors that were common only a decade ago (and many shops have old ones in their used bins) or you can bypass them and use a clamp around double stop. Or just run full length casing from the shifters to the ders.

Depending on your preferences and what's available via shop scrap boxes or a local coop/bike kitchen (how I hate that term but it does work) costs can range from a few tens of $ to more.

Last thing I will add for now is the seat. Most will think it's unrelated but with the more upright stance you'll have with the closer and nondrop bars expect to be placing more weight on the seat. We see the seat changed out frequently too in these transformations. Andy

ramzilla

Easy peasy. My favorite thumbies are NOS Suntour. Sometimes can be found on ebay for around $35/pair.

https://www.ebay.com/itm/MAEDA-SUNTO...ox!32034!US!-1

Bagel Bob

Thanks! One more question. Will Shimano indexed shifters work with the Suntour derailers and gears as long as it made for a 7x3 set?

cpach

No.

mitchmellow62

It's a crap shoot. The best answer is probably not. Most of the Suntour derailleurs had a different cable pull than shimano. However, I did use 7 speed Shimano shifters with a Suntour Alpha 3000 mountain derailleur and it worked fine.

Andrew R Stewart 

I'll add that what works when all is new and tight/not worn and how that arrangement works when the miles/grit/sloppiness have added up can be rather frustrating. When gear system parts are sort of agreeable they cam fall out of liking each other faster then made for each other combines. Andy

ramzilla

The good news with old Suntour Accushift stuff is that it has dual mode feature. Can be operated friction mode or index mode. In my experience the index mode is compatible on either 6 speed Shimano or Suntour. But, not so much on 7 speed set ups. Suntour equipment disappeared sometime around the end of the 1980's and Shimano set the standard for 7 speed stuff after that.