Shifting problem with Suntour Blaze - help?
Jake Sloan
components, 7 speed indexed downtube shifters, triple crank.
I found a set of NOS Suntour bar-end shifters for her (7 speed
accushift) and installed them for her. They seemed to work fine
in the stand and the quick test ride I took. But when she took
it out for a ride, it would occasionally "jump" in the rear so
that it sounded like it was between gears. It didn't actually
jump to a different gear. To rectify, she shifted to another gear
and then back, and it was fine again.
The shifter is fine, so I suspect the rear derailleur is shot
somehow. Has the spring lost tension? Is there side to side play
that is causing it to jump? I haven't had a chance to check, and
I'n not sure I'll be able to recognize the problem anyway.
Assuming the rear derailleur is the problem, can I just buy a
current Shimano 105 long cage rear derailleur? Will the Suntour
shifters work ok with Shimano, or is the geometry not the same?
If the Suntour shifters won't work well, I guess I will have to
buy some old Shimano 7 speed shifters, and a Sachs 7 speed
freewheel to get it all to work? If that's the case, maybe it
is time to bite the bullet and upgrade rear hub and everything else
to Shimano 9 speed?
Thanks,
Jake
Mike Jacoubowsky
finnicky about chain choice. The best chains I found for them (after the
Suntour chains disappeared) were made by KMC. For now, I'd pull the cables
out of their housings and make sure they're well greased (possibly replace
them), get some grease in the cable guides under the bottom bracket, and
make sure the derailleur pivot points are lubed up.
Unfortunately, you can't replace the rear derailleur with anything but
another Suntour and have it work with Suntour shifters... and since Suntour
stopped making derailleurs a long time ago, that might be a difficult thing
to find. You *could* upgrade everything to 9-speed, but you'll have to
spread the frame and replace the rear wheel, and the expense is high enough
that you need to make sure you wouldn't be best served with a new bike.
--Mike--
Chain Reaction Bicycles
http://www.ChainReaction.com
"Jake Sloan" <jake...@hotmail.com> wrote in message
news:688f6314.02041...@posting.google.com...
Benjamin Weiner
> I found a set of NOS Suntour bar-end shifters for her (7 speed
> accushift) and installed them for her. They seemed to work fine
> in the stand and the quick test ride I took. But when she took
> it out for a ride, it would occasionally "jump" in the rear so
> that it sounded like it was between gears. It didn't actually
> jump to a different gear. To rectify, she shifted to another gear
> and then back, and it was fine again.
Maybe it's the new cable and housing settling in? If the
derailleur is really worn out you should be able to find
play in the cage pivots by twisting the cage.
> Assuming the rear derailleur is the problem, can I just buy a
> current Shimano 105 long cage rear derailleur? Will the Suntour
> shifters work ok with Shimano, or is the geometry not the same?
> If the Suntour shifters won't work well, I guess I will have to
> buy some old Shimano 7 speed shifters, and a Sachs 7 speed
> freewheel to get it all to work? If that's the case, maybe it
> is time to bite the bullet and upgrade rear hub and everything else
> to Shimano 9 speed?
The Suntour and Shimano derailleurs have slightly different
geometry, and the Shimano der has that floating pulley.
A Shimano 8-speed barend shifter (available new) and Shimano
derailleur are supposed to work well on 7-speed setups, and
they would probably work on the existing Suntour freewheel.
A Muzi
Shimano equipment is not compatible in your system.
From your dedscription of teh symptom, check first that the rear changer
cage is parallel to the chainrings. Get your head behind the changer and
sight the cage against the rings.
If that's OK, and I bet it is close, a more likely explanation is a binding
link or a worn chain. Backpedal slowly in the small-small combination and
look for a jump or hop in the chain as it passes the rear 13t. A binding
rivet can be freed with a chain tool using the back slot. If that seems OK,
check the elongation of the chain over twelve inches to ensure it's less
than 1/8". If worn, try the widest available chain, KMC "Z" chain for
example. This may open a can of worms as a matching worn Suntour freewheel
will be a bit expensive.
--
Andrew Muzi
http://www.yellowjersey.org
Open every day since 1 April 1971
A Muzi
news:3cbd1106$1...@news.ucsc.edu...
That would do it in the extreme case of new shifters, cables, rear changer
and a Shimano-compatible freewheel plus a new chain. Seems a bit excessive
to me.
Jake Sloan
I'll have a chance to check out the bike more carefully this
weekend, and will examine the chain, cable, and derailleur more
closely.
If the derailleur is indeed the problem, I'll first take a look
around for a new or newish Suntour derailleur. Question - will
any 7 speed Suntour derailleur work? There seem to be more "offroad"
derailleurs available on ebay, such as the XC Comp that is
up for auction now. I'm assuming this would be ok to use?
If I can't find a suitable Suntour derailleur, I'll find Shimano
7 speed shifters, either downtube or barend, and a 7 or 8 speed era
Shimano derailleur. Fairly easy to find both. And I'll probably
throw on a Sachs 7 speed freewheel and pc-58 chain.
I won't go for (and she won't pay for!) the whole 9 speed STI route.
Thanks again!
Jake