Stronglight Chainsets

[CREPELLO]

Unfortunately replacement rings for the Impact chainset are becoming harder to find, so I would be hesitant to recommend them.

I am surprised and concerned by this. Is there any other brand of ring that fits? TA, Middleburn? I really want the Zicral 7075 rings as well, and not the 2014 Dural ones that I'd suggested were the harder ones in my previous post.

[CREPELLO]

The Impact chainset appears to have changed, if CRC are to be believed. Rather confusingly, they are still selling the 'old'
design here with a higher retail price than the new one - £89 compared to £74.

Has anyone bought one of these new designs yet? It looks to have all new chain rings with fully profiled teeth and a new spider design to boot.

I bought some Dural rings for my Impact recently and I'm very impressed with their appearence .
Lovely bevelled edges that actually put the appearence of the Record chainset on the Mercian to shame No!

[MacBludgeon]

Folks can I dive in here with a quick, though lengthy, couple of questions please? I've gotten enough answers elsewhere to hopefully be asking the right questions now. I've got two bike builds I'm trying to sort drive trains for, thought I was sorted via delving through Sheldons site. However various gear set ups you can view on his gear calculator don't seem to be readily available in reality. So:-

Bike 1 - social road use, possible very light credit card touring - existing bike has a 9 speed 30/42/52 and 12-26 cassette - I find I ride in the 42 ring all the time unless it gets really steep, the 52 hasn't been used in 2.5k miles - I considered running a single chainring and broad range 9 speed cassette but would rather run a compact double and narrower cassette - I had thought 42/26 rings would be nice until I discovered BCD's etc - I found the Stronglight Oxale Two as a 29/44 double but it is a funny ISIS BB and I wanted to stick with square taper - have found various 94 BCD options, Middleburn, FSA etc, thus allowing down to a 29 inner but they seem to come with a price tag of £200 upwards, some very nice ones at £460+ - as most of my riding is in the 50-80 inch range I find a lot of standard compact setups would mean I changed rings a lot more - So I'm looking for a compact chainset 29/44 or 29/42 that won't break the bank, runs on square taper and parts are easy to source? - Also, I understand derailler/cassette compatibility, but is there anything re cassette/chainrings I should be aware of?

Bike 2 - general mess about pub/shop bike being built as a 29er around a Surly Karate Monkey frameset - I want to run this as a single chainring and 8/9 speed cassette - what works with what re chainlines etc so that I can hit the whole cassette from the single ring? - Do I just take the measurement from the BB of the middle ring of a MTB triple and then try to get a single to match that? - Why do all the broad range cassettes come with an 11t cog unless you spend crazy money for a Shimano XTR which comes in 9 speed 12-34?

I was directed to White Industries who do a very nifty outer ring with slots instead of bolt holes, VBC - variable bolt cirlce, so you can marry up any inner(26/28/30/32/36/38) with any outer(42/44/46/48/50/52), but £220 seems a lot:-
http://www.whiteind.co.uk/#/vbc-road/4533316798

Any assistance gratefully appreciated....thanks.....Al

[frank9755]

It seems you've got to use the right chain with Stronlight chainsets. This has been my experience with the Impact. It doesn't have the teeth profiling or ramps of modern Shimano chainrings, for example; only a few pins. I've just removed a KMC-X993 chain from a Stronglight equipped bike because of very poor gear changes. Now, it may be the unhappy combination the chainset and this chain. I don't know if other KMC chains have the same profile, but that's the problem - very little useful sculpting of the links. The 'X' profile on the outer links appears largely superficial; there's no discernible bulge or bevelling of the edges. It wasn't that good at rear changes either, though it was a very quiet chain.

I've just replaced this with a SRAM pc971 - it's profiling looks well designed with a good bulge in the outer link. On the workstand, gear changes were largely crisp; I'm expecting the test run to be fine. Previously I've run Shimano chains with the chainset with no problem.

This is interesting. I'm having problems with the upshift from middle to top chainrings on my new bike. I'm using an Impact with a 50T outer and a 39T middle - which is what my Shimano 105 mech insists on having. I am also using a KMC chain. I've just ordered a Wippermann and a SRAM chain to see if either of them will do the trick.

[reohn2]

I'm running three S/light Impact triple chainsets.One bike has 9sp(14-25)with 26-36-48 rings, second bike 7sp(13-26)with 28-36-48rings,both bikes use Sram chains and the change(with shimano STI's) is flawless .The third bike is 7sp(11-28) with 28-38-46 and a KMC chain(don't know which model but I suspect its the cheapest) again flawless changes with Kelly take off's and shimano levers.

[frank9755]

I also have an Impact on another bike. It has a Tiagra front mech and has upshifted fine whatever chain it has been faced with. In 7,500 miles it has had a go at most brands, but probably the Wippermann has been the sweetest.

My new bike is 10-speed with the new series 105 (7500) kit. I think that is more fussy than older Shimano. I'm hoping that the new chains work. Next thing I'd try would be a new ring - probably a TA, which would have better ramps and pins than the Stronglight has. If that didn't work I think I'd have to admit defeat and get a Shimano chainset.

The way that the upshift is failing to work is rather odd (to me at least) in that it is not because the mech is failing to throw the chain far enough. It is, and two times out of three it will upshift well. However on the third occasion, it will put the pins of the chain on the ends of the chainwheel teeth, where they don't grip, and the chain will fail to slip into the gaps between the teeth for a couple of seconds. Curious!

[531colin]

The way that the upshift is failing to work is rather odd (to me at least) in that it is not because the mech is failing to throw the chain far enough. It is, and two times out of three it will upshift well. However on the third occasion, it will put the pins of the chain on the ends of the chainwheel teeth, where they don't grip, and the chain will fail to slip into the gaps between the teeth for a couple of seconds. Curious!

If the rollers are staying on the tops of the teeth, it suggests to me that the teeth on the 2 rings are "out of phase" at the point where you habitually change gear. (At least, I habitually change gear at one point - you can see the wear on the back of the rings). I think you just need to rotate a ring on the spider until all is well. Have to be the small ring if you use the peg which is intended to stop the chain falling between crank and ring.

[Steve Kish]

The things I remember about the Stronglight Criterium are firstly, that it was so easy to round the five ring bolts and secondly, you could quite easily get stupidly large rings for these, from 57T right up to about 72T .... but at a price!

[frank9755]

If the rollers are staying on the tops of the teeth, it suggests to me that the teeth on the 2 rings are "out of phase" at the point where you habitually change gear. (At least, I habitually change gear at one point - you can see the wear on the back of the rings). I think you just need to rotate a ring on the spider until all is well. Have to be the small ring if you use the peg which is intended to stop the chain falling between crank and ring.

Thanks Colin but, funnily enough, this occurred to me last night. I reasoned that with a 40T ring there would be 8 teeth between each bolt so it would be the same pattern at each bolt, but for a 39T there would be a different orientation in each position. So I did exactly that - moved the middle ring round by two places. Unfortunately it didn't fix the problem! It might of course work in a third position, but I'm not very optimistic so I'll try different chains first.

[531colin]

Im guessing the chain drops into mesh when it has peeled off the ring its leaving, ie. there is no slack to let the chain drop down until its clear of that ring. As all chains are half inch pitch, I dont know that a different make will help. What will differ? Sideplate shape? Sideways flexibility?

[frank9755]

I don't know, but you make another good point.

It is a strange one. Do you think another position might work? Or a different ring? A 50T TA ring would have better ramping but maybe that would be as irrelevant as a different side plate shape. As it would obviously have the same number of teeth as a 50T Stonglight one, nothing would change regarding the way the chain engages with the big ring once it is on it.

Maybe I have a bit of a duff big ring which just isn't picking up the chain like it should...?

I'm a bit stumped!

[531colin]

Can you reproduce the fault on the workstand?
I imagine what happens is this
1) chain on small ring
2) mech. shoves chain against big ring
3) big ring picks up chain, but rollers rest on top of teeth
4) half turn of pedals later, chain peels off small ring at bottom run of chain
5) At that instant, NO teeth at all are engaged, so the crank can slip round under the chain and engage the teeth on the big ring.

If Im right, rotating the ring so the teeth are "in phase" should work.

When I look at the back of my chainrings, I can see wear where I habitually change rings at a particular part of the circle.
Do you see that? Thats the point where the teeth need to be " in phase" . I dont think they will be in phase all the way round.

NB point 4 doesnt agree with your "couple of seconds" for the chain to drop down, it would be much quicker than that!

[frank9755]

Can you reproduce the fault on the workstand?
I imagine what happens is this
1) chain on small ring
2) mech. shoves chain against big ring
3) big ring picks up chain, but rollers rest on top of teeth
4) half turn of pedals later, chain peels off small ring at bottom run of chain
5) At that instant, NO teeth at all are engaged, so the crank can slip round under the chain and engage the teeth on the big ring.

If Im right, rotating the ring so the teeth are "in phase" should work.

When I look at the back of my chainrings, I can see wear where I habitually change rings at a particular part of the circle.
Do you see that? Thats the point where the teeth need to be " in phase" . I dont think they will be in phase all the way round.

NB point 4 doesnt agree with your "couple of seconds" for the chain to drop down, it would be much quicker than that!

Thanks again, Colin for thinking about it.

Yes I can reproduce it on the stand, just been out fiddling with it again!

I would agree with you about rotating the ring if I hadn't already tried that yesterday! It didn't make any difference. OK I've tried two of the five positions but can't think why the other three would be better. My second one was two bolts round, so phase difference to any of the other three will be v. small. Also, it works ok half of the time now, which is consistent with the 'out of phase' theory, but perhaps suggests that maybe I shift more at different points in my pedalling cycle and therefore can't solve the problem by aiming for the right phasing at one given point.

I think your sequence of what happens is correct. You are right, my couple of seconds is an exaggeration. It's possibly a third of a second, but a long time with a rattling chain!

What I did notice was how flat the ends of the teeth on my Impact big ring are! My middle ring, a TA (from SPA last week!), has much more rounded teeth. My other Impact seems to have slightly more rounded teeth on the big ring - although that could be wear as it has done a few miles, and my other bikes (an old Stronglight, a Shimano and 2x Truvativ chainsets) are all more rounded.

I now think that getting a different ring with more rounded teeth so the rollers have a bigger gap to aim for might just do it.

Edit - here's a picture of my chainset. The big ring teeth look very flat:


Much flatter than pictures of the Impact on Spa's site or ChainReaction (which I don't seem to be able to copy but click here http://www.chainreactioncycles.com/Images/Models/Original/43350.jpg)

[531colin]

Id be inclined to file those teeth to a shape like the inner ring.
Look closely at a ring thats done some miles, you can see where the chain bears on the teeth, thats the bit not to file!

[CREPELLO]

The fact that you can get the chain to shift 2 out of 3 times means that you nearly there. There are often idiosyncrasies when mixing up different brands, even if the theory says they should work. Trusting that everything else is optimised, what I'd advocate is a little gentle mech cage manipulation. Don't worry, you're not going to butcher it. I've done it countless times and it has usually improved the shifting.

I don't know the new 105 cage profile , but the old one showed a distinct bend inwards at the top front edge of the inside plate. This is there to help lift and nudge the chain onto the large ring. I had trouble shifting (as you flagged up) and had trouble again with another Impact equipped bike - both now matched with Campag triple front mechs. I spent endless hours feckin and fettling, changing chain rings, filing down teeth. Nothing worked until I looked closely at the gear change on the work stand. My Mercian too showed the tendency for the chain to ride up onto the outer ring teeth, only to fall back.

What I did was to get some good quality mole grips onto the inside cage plate (top leading edge) and bend it in ever so slightly,1.5mm. I may have removed the chain set first for better access.
The effect was instantaeous in nudging the chain just that little bit further. The mod had the happy result of only coming into contact with the chain as it rode up the outer ring, meaning that it didn't cause chain rub at all.

I hope this is relevent to you.

By the way, the trouble I was having, described previously, was in part because I'd ordered a double inner ring, without any ramps and pins, instead of a triple middle. The mod above on the Cheviot now ensures perfect changes, so ramps and pins aren't essential at all. I seem to have repeated the mistake again this year with new rings for Offa's Bike. So I ordered a TA middle triple, but to no avail - the changes were only a little better and far from perfect. So the incorrect Stronglight inner rings are now on both bikes as middles with the described mech mod and I am very content....AT LAST!