Chrisman183

Hi, I know nothing about this, so thought I'd ask here. I have downtube friction shifters on my 6 speed trek, if I change the cassette out with a newer one (10sp) would I need to get new shifters or could these work with the much larger set? I know I'd have to get a new derailleur but I'm wondering about the shifters... if they won't work, would anyone have a recommendation where to find a compatible set of downtube shifters?

thanks!!

fordbailey

They'll work, but it will probably be tricky to trim gears perfectly, as the sprockets on the cassette are closer together. It's worth trying- no harm in that.

20grit

Are you sure the 6 speed is a cassette? If it's a freewheel instead of freehub, then a cassette isn't going to work.
You will probably need a new chain.

ridelikeaturtle

With Simplex DT friction shifters on an old Bianchi that was 5-speed, I found it will only cover 8 cogs of a 9-speed campy cassette. I have to adjust the RD to choose if I want to achieve the largest cog, or smallest cog - but I can't have both.

Does anyone know if different DT shifters would have a greater range and cover the whole cassette?

Bianchigirll 

20grit

Good catch Bianchigirll. I've been away from the forum for a while. I'd have caught that if I were still on my old posting/viewing schedule.

Dfrost 

smoothness 

according to most people who have done this, you'll need newer downtube shifters which have a larger barrel diameter for the cables to wrap around; if you choose to use old ones, you might find that you run out of the necessary cable pull. i also echo the other posts questioning whether your freehub is wide enough to take a 10s cassette; measure the freehub against another freehub that you know can take 8s or larger.

John E

Many Simplex shifters had absurdly small capstan diameters. Look for a different shifter, which may require a clamp-on mounting bracket (been there ... done that with my 1980 PKN-10), with a larger capstan.

seamuis

MarcoBianchi

If you can run a 10s cassette and you DT shifters aren't enough, this is a really bargain:
Juego de manetas de cambio para tubo diagonal Shimano Dura-Ace 7900 10v | Chain Reaction Cycles

MarcoBianchi

Excuse me, I posted the Spanish CRC page.

Podagrower

YMMV, but I picked up an 80's bike with downtube shifters, Shimano 105 6 speed indexed. They had enough cable pull to handle a 10 speed cassette, but I did drop the coin for the Dura Ace shifters above.

seamuis

ridelikeaturtle

Yeah, I was kinda hoping for <20eur old-school suntour or campy shifters, for my "old heavy" Bianchi Sprint 76!

Road Fan

I suspect we confused the heck out of the thread author, who needed some help.

Road Fan

I'm pretty sure even the earlier 1977 Trek frames came with 126 mm spacing, not 120 mm. So the difference in over-locknut distance between a 10 speed wheel and a 6-speed wheel should be 4 mm. My 7-speed 1984 Trek 610 came with 126 mm Maillard Helicomatic wheels, which had some of the benefits of cassettes and some of the benefits of freewheels. The main problem with them is the entire Helicomatic system is LOOONNNGGGG out of production, and essentially zero replacement freewheels are available. To be able to experiment with gearing, et cetera I got a used set of wheels built on Shimano 600 6208 freewheel hubs. Perfect fit in the frame, good bearings, still running.

We really don't have enough basic information about the OP's bike, save that it's an "old Trek."

smoothness 

He asked for a small bit of knowledge, not expecting the torrent of unfocused dissenting voices, all vying for recognition in a virtual sea of bits and bytes.

Yeah. He's definitely confused AF.

ridelikeaturtle

If he changes out the cassette "with a newer one (10sp)", then he'd need to get DT shifters with a range wide enough - apparently older Simplex shifters won't work (as they won't cover my 9-speed campy cassette), but newer ones with a larger range should.

I don't see how the rear derailleur really cares so much, as long as it's designed to cover what it covers, 8-9-10 speed, as it's only getting pulled by a shifter. Any friction shifter, if it has the range, should work. I can only say that the Simplex shifters I have will only get you to 8 of 9 cogs on a 9-speed campy cassette (and so will not cover 10 either, in all likelihood).

I'll give Suntour a shot first. I'm reluctant to use Shimano, though I know they'd work, but it's irrational and I'm biased. If this is my only irrational thought (to not use Shimano even though they'd certainly be the superior DT shifter for my use), then I'm doing OK.

Chrisman183

wow, ok, yeah thank you all for responding! I am a little bit overwhelmed with all of it haha, but Id rather have too much info than not enough.

anyway to give some responses to the above, I have a 10sp cassette lying around in the garage, I was going to buy a new wheelset to use with that cassette and put on the bike, assuming that it will fit the bike (I still haven't measured yet). And not even sure what exactly to measure, the space between the QR brackets? or the axle length or is that the same thing. And what type of 'wiggle room' would I have on a steel frame bike? any? is that 4mm difference someone mentioned too much or ok?

currently the DT shifters and the derailleur are shimano 600 series. but it's weird because the shifters are friction, and the derailleur is labeled as SIS, but they are a set? But that is what I have planned to do. I did notice the 6sp on there now is a lot wider spaced between the gears than what a normal 8/9/10sp is, so, MAYBE I would be able to use the derailleur that is on there now also. Not sure.
thanks again for all the tips and suggestions! I like the shimano shifters mentioned above by a couple of you. If the 600 shifters don't have enough range I will likely look at the dura ace, although they are a little high.
I'll try to get in the attic to take some measurements this week.
EDIT: oh yeah, sorry it's a late 70s Trek 510